CSV_XS(3)

User Contributed Perl Documentation

CSV_XS(3)

NAME¶

Text::CSV_XS - comma-separated values manipulation routines

SYNOPSIS¶

 # Functional interface
 use Text::CSV_XS qw( csv );
 # Read whole file in memory
 my $aoa = csv (in => "data.csv");    # as array of array
 my $aoh = csv (in => "data.csv",
                headers => "auto");   # as array of hash
 # Write array of arrays as csv file
 csv (in => $aoa, out => "file.csv", sep_char => ";");
 # Only show lines where "code" is odd
 csv (in => "data.csv", filter => { code => sub { $_ % 2 }});
 # Object interface
 use Text::CSV_XS;
 my @rows;
 # Read/parse CSV
 my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
 open my $fh, "<:encoding(utf8)", "test.csv" or die "test.csv: $!";
 while (my $row = $csv->getline ($fh)) {
     $row->[2] =~ m/pattern/ or next; # 3rd field should match
     push @rows, $row;
     }
 close $fh;
 # and write as CSV
 open $fh, ">:encoding(utf8)", "new.csv" or die "new.csv: $!";
 $csv->say ($fh, $_) for @rows;
 close $fh or die "new.csv: $!";

DESCRIPTION¶

Text::CSV_XS provides facilities for the composition and decomposition of comma-separated values. An instance of the Text::CSV_XS class will combine fields into a "CSV" string and parse a "CSV" string into fields.

The module accepts either strings or files as input and support the use of user-specified characters for delimiters, separators, and escapes.

Embedded newlines¶

Important Note: The default behavior is to accept only ASCII characters in the range from 0x20 (space) to 0x7E (tilde). This means that the fields can not contain newlines. If your data contains newlines embedded in fields, or characters above 0x7E (tilde), or binary data, you must set "binary => 1" in the call to "new". To cover the widest range of parsing options, you will always want to set binary.

But you still have the problem that you have to pass a correct line to the "parse" method, which is more complicated from the usual point of usage:

 my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
 while (<>) {           #  WRONG!
     $csv->parse ($_);
     my @fields = $csv->fields ();
     }

this will break, as the "while" might read broken lines: it does not care about the quoting. If you need to support embedded newlines, the way to go is to not pass "eol" in the parser (it accepts "\n", "\r", and "\r\n" by default) and then

 my $csv = Text::CSV_XS->new ({ binary => 1 });
 open my $fh, "<", $file or die "$file: $!";
 while (my $row = $csv->getline ($fh)) {
     my @fields = @$row;
     }

The old(er) way of using global file handles is still supported

 while (my $row = $csv->getline (*ARGV)) { ... }

Unicode¶

Unicode is only tested to work with perl-5.8.2 and up.

BOM¶

BOM (or Byte Order Mark) handling is available only inside the "header" method. This method supports the following encodings: "utf-8", "utf-1", "utf-32be", "utf-32le", "utf-16be", "utf-16le", "utf-ebcdic", "scsu", "bocu-1", and "gb-18030". See Wikipedia <https://en.wikipedia.org/wiki/Byte_order_mark>.

If a file has a BOM, the easiest way to deal with that is

 my $aoh = csv (in => $file, detect_bom => 1);

All records will be encoded based on the detected BOM.

This implies a call to the "header" method, which defaults to also set the "column_names". So this is not the same as

 my $aoh = csv (in => $file, headers => "auto");

which only reads the first record to set "column_names" but ignores any meaning of possible present BOM.

SPECIFICATION¶

While no formal specification for CSV exists, RFC 4180 <https://datatracker.ietf.org/doc/html/rfc4180> (1) describes the common format and establishes "text/csv" as the MIME type registered with the IANA. RFC 7111 <https://datatracker.ietf.org/doc/html/rfc7111> (2) adds fragments to CSV.

Many informal documents exist that describe the "CSV" format. "How To: The Comma Separated Value (CSV) File Format" <http://creativyst.com/Doc/Articles/CSV/CSV01.shtml> (3) provides an overview of the "CSV" format in the most widely used applications and explains how it can best be used and supported.

 1) https://datatracker.ietf.org/doc/html/rfc4180
 2) https://datatracker.ietf.org/doc/html/rfc7111
 3) http://creativyst.com/Doc/Articles/CSV/CSV01.shtml

The basic rules are as follows:

CSV is a delimited data format that has fields/columns separated by the comma character and records/rows separated by newlines. Fields that contain a special character (comma, newline, or double quote), must be enclosed in double quotes. However, if a line contains a single entry that is the empty string, it may be enclosed in double quotes. If a field's value contains a double quote character it is escaped by placing another double quote character next to it. The "CSV" file format does not require a specific character encoding, byte order, or line terminator format.

Each record is a single line ended by a line feed (ASCII/"LF"=0x0A) or a carriage return and line feed pair (ASCII/"CRLF"="0x0D 0x0A"), however, line-breaks may be embedded.
Fields are separated by commas.
Allowable characters within a "CSV" field include 0x09 ("TAB") and the inclusive range of 0x20 (space) through 0x7E (tilde). In binary mode all characters are accepted, at least in quoted fields.
A field within "CSV" must be surrounded by double-quotes to contain a separator character (comma).

Though this is the most clear and restrictive definition, Text::CSV_XS is way more liberal than this, and allows extension:

Line termination by a single carriage return is accepted by default
The separation-, quote-, and escape character(s) can be any ASCII character in the range from 0x20 (space) to 0x7E (tilde). Characters outside this range may or may not work as expected. Multibyte characters, like UTF "U+060C" (ARABIC COMMA), "U+FF0C" (FULLWIDTH COMMA), "U+241B" (SYMBOL FOR ESCAPE), "U+2424" (SYMBOL FOR NEWLINE), "U+FF02" (FULLWIDTH QUOTATION MARK), and "U+201C" (LEFT DOUBLE QUOTATION MARK) (to give some examples of what might look promising) work for newer versions of perl for "sep_char", and "quote_char" but not for "escape_char".
If you use perl-5.8.2 or higher these three attributes are utf8-decoded, to increase the likelihood of success. This way "U+00FE" will be allowed as a quote character.
A field in "CSV" must be surrounded by double-quotes to make an embedded double-quote, represented by a pair of consecutive double-quotes, valid. In binary mode you may additionally use the sequence ""0" for representation of a NULL byte. Using 0x00 in binary mode is just as valid.
Several violations of the above specification may be lifted by passing some options as attributes to the object constructor.

METHODS¶

version¶

(Class method) Returns the current module version.

new¶

(Class method) Returns a new instance of class Text::CSV_XS. The attributes are described by the (optional) hash ref "\%attr".

 my $csv = Text::CSV_XS->new ({ attributes ... });

The following attributes are available:

eol

 my $csv = Text::CSV_XS->new ({ eol => $/ });
           $csv->eol (undef);
 my $eol = $csv->eol;

The end-of-line string to add to rows for "print" or the record separator for "getline".

When not passed in a parser instance, the default behavior is to accept "\n", "\r", and "\r\n", so it is probably safer to not specify "eol" at all. Passing "undef" or the empty string behave the same.

When not passed in a generating instance, records are not terminated at all, so it is probably wise to pass something you expect. A safe choice for "eol" on output is either $/ or "\r\n".

Common values for "eol" are "\012" ("\n" or Line Feed), "\015\012" ("\r\n" or Carriage Return, Line Feed), and "\015" ("\r" or Carriage Return). The "eol" attribute cannot exceed 7 (ASCII) characters.

If both $/ and "eol" equal "\015", parsing lines that end on only a Carriage Return without Line Feed, will be "parse"d correct.

sep_char

 my $csv = Text::CSV_XS->new ({ sep_char => ";" });
         $csv->sep_char (";");
 my $c = $csv->sep_char;

The char used to separate fields, by default a comma. (","). Limited to a single-byte character, usually in the range from 0x20 (space) to 0x7E (tilde). When longer sequences are required, use "sep".

The separation character can not be equal to the quote character or to the escape character.

known_attributes¶

 @attr = Text::CSV_XS->known_attributes;
 @attr = Text::CSV_XS::known_attributes;
 @attr = $csv->known_attributes;

This method will return an ordered list of all the supported attributes as described above. This can be useful for knowing what attributes are valid in classes that use or extend Text::CSV_XS.

print¶

 $status = $csv->print ($fh, $colref);

Similar to "combine" + "string" + "print", but much more efficient. It expects an array ref as input (not an array!) and the resulting string is not really created, but immediately written to the $fh object, typically an IO handle or any other object that offers a "print" method.

For performance reasons "print" does not create a result string, so all "string", "status", "fields", and "error_input" methods will return undefined information after executing this method.

If $colref is "undef" (explicit, not through a variable argument) and "bind_columns" was used to specify fields to be printed, it is possible to make performance improvements, as otherwise data would have to be copied as arguments to the method call:

 $csv->bind_columns (\($foo, $bar));
 $status = $csv->print ($fh, undef);

A short benchmark

 my @data = ("aa" .. "zz");
 $csv->bind_columns (\(@data));
 $csv->print ($fh, [ @data ]);   # 11800 recs/sec
 $csv->print ($fh,  \@data  );   # 57600 recs/sec
 $csv->print ($fh,   undef  );   # 48500 recs/sec

say¶

 $status = $csv->say ($fh, $colref);

Like "print", but "eol" defaults to "$\".

print_hr¶

 $csv->print_hr ($fh, $ref);

Provides an easy way to print a $ref (as fetched with "getline_hr") provided the column names are set with "column_names".

It is just a wrapper method with basic parameter checks over

 $csv->print ($fh, [ map { $ref->{$_} } $csv->column_names ]);

combine¶

 $status = $csv->combine (@fields);

This method constructs a "CSV" record from @fields, returning success or failure. Failure can result from lack of arguments or an argument that contains an invalid character. Upon success, "string" can be called to retrieve the resultant "CSV" string. Upon failure, the value returned by "string" is undefined and "error_input" could be called to retrieve the invalid argument.

string¶

 $line = $csv->string ();

This method returns the input to "parse" or the resultant "CSV" string of "combine", whichever was called more recently.

getline¶

 $colref = $csv->getline ($fh);

This is the counterpart to "print", as "parse" is the counterpart to "combine": it parses a row from the $fh handle using the "getline" method associated with $fh and parses this row into an array ref. This array ref is returned by the function or "undef" for failure. When $fh does not support "getline", you are likely to hit errors.

When fields are bound with "bind_columns" the return value is a reference to an empty list.

The "string", "fields", and "status" methods are meaningless again.

getline_all¶

 $arrayref = $csv->getline_all ($fh);
 $arrayref = $csv->getline_all ($fh, $offset);
 $arrayref = $csv->getline_all ($fh, $offset, $length);

This will return a reference to a list of getline ($fh) results. In this call, "keep_meta_info" is disabled. If $offset is negative, as with "splice", only the last "abs ($offset)" records of $fh are taken into consideration. Parameters $offset and $length are expected to be integers. Non-integer values are interpreted as integer without check.

Given a CSV file with 10 lines:

 lines call
 ----- ---------------------------------------------------------
 0..9  $csv->getline_all ($fh)         # all
 0..9  $csv->getline_all ($fh,  0)     # all
 8..9  $csv->getline_all ($fh,  8)     # start at 8
 -     $csv->getline_all ($fh,  0,  0) # start at 0 first 0 rows
 0..4  $csv->getline_all ($fh,  0,  5) # start at 0 first 5 rows
 4..5  $csv->getline_all ($fh,  4,  2) # start at 4 first 2 rows
 8..9  $csv->getline_all ($fh, -2)     # last 2 rows
 6..7  $csv->getline_all ($fh, -4,  2) # first 2 of last  4 rows

getline_hr¶

The "getline_hr" and "column_names" methods work together to allow you to have rows returned as hashrefs. You must call "column_names" first to declare your column names.

 $csv->column_names (qw( code name price description ));
 $hr = $csv->getline_hr ($fh);
 print "Price for $hr->{name} is $hr->{price} EUR\n";

"getline_hr" will croak if called before "column_names".

Note that "getline_hr" creates a hashref for every row and will be much slower than the combined use of "bind_columns" and "getline" but still offering the same easy to use hashref inside the loop:

 my @cols = @{$csv->getline ($fh)};
 $csv->column_names (@cols);
 while (my $row = $csv->getline_hr ($fh)) {
     print $row->{price};
     }

Could easily be rewritten to the much faster:

 my @cols = @{$csv->getline ($fh)};
 my $row = {};
 $csv->bind_columns (\@{$row}{@cols});
 while ($csv->getline ($fh)) {
     print $row->{price};
     }

Your mileage may vary for the size of the data and the number of rows. With perl-5.14.2 the comparison for a 100_000 line file with 14 columns:

            Rate hashrefs getlines
 hashrefs 1.00/s       --     -76%
 getlines 4.15/s     313%       --

getline_hr_all¶

 $arrayref = $csv->getline_hr_all ($fh);
 $arrayref = $csv->getline_hr_all ($fh, $offset);
 $arrayref = $csv->getline_hr_all ($fh, $offset, $length);

This will return a reference to a list of getline_hr ($fh) results. In this call, "keep_meta_info" is disabled.

parse¶

 $status = $csv->parse ($line);

This method decomposes a "CSV" string into fields, returning success or failure. Failure can result from a lack of argument or the given "CSV" string is improperly formatted. Upon success, "fields" can be called to retrieve the decomposed fields. Upon failure calling "fields" will return undefined data and "error_input" can be called to retrieve the invalid argument.

You may use the "types" method for setting column types. See "types"' description below.

The $line argument is supposed to be a simple scalar. Everything else is supposed to croak and set error 1500.

fragment¶

This function tries to implement RFC7111 (URI Fragment Identifiers for the text/csv Media Type) - https://datatracker.ietf.org/doc/html/rfc7111

 my $AoA = $csv->fragment ($fh, $spec);

In specifications, "*" is used to specify the last item, a dash ("-") to indicate a range. All indices are 1-based: the first row or column has index 1. Selections can be combined with the semi-colon (";").

When using this method in combination with "column_names", the returned reference will point to a list of hashes instead of a list of lists. A disjointed cell-based combined selection might return rows with different number of columns making the use of hashes unpredictable.

 $csv->column_names ("Name", "Age");
 my $AoH = $csv->fragment ($fh, "col=3;8");

If the "after_parse" callback is active, it is also called on every line parsed and skipped before the fragment.

row

 row=4
 row=5-7
 row=6-*
 row=1-2;4;6-*

col

 col=2
 col=1-3
 col=4-*
 col=1-2;4;7-*

cell

In cell-based selection, the comma (",") is used to pair row and column

 cell=4,1

The range operator ("-") using "cell"s can be used to define top-left and bottom-right "cell" location

 cell=3,1-4,6

The "*" is only allowed in the second part of a pair

 cell=3,2-*,2    # row 3 till end, only column 2
 cell=3,2-3,*    # column 2 till end, only row 3
 cell=3,2-*,*    # strip row 1 and 2, and column 1

Cells and cell ranges may be combined with ";", possibly resulting in rows with different numbers of columns

 cell=1,1-2,2;3,3-4,4;1,4;4,1

Disjointed selections will only return selected cells. The cells that are not specified will not be included in the returned set, not even as "undef". As an example given a "CSV" like

 11,12,13,...19
 21,22,...28,29
 :            :
 91,...97,98,99

with "cell=1,1-2,2;3,3-4,4;1,4;4,1" will return:

Overlapping cell-specs will return those cells only once, So "cell=1,1-3,3;2,2-4,4;2,3;4,2" will return:

 11,12,13
 21,22,23,24
 31,32,33,34
 42,43,44

RFC7111 <https://datatracker.ietf.org/doc/html/rfc7111> does not allow different types of specs to be combined (either "row" or "col" or "cell"). Passing an invalid fragment specification will croak and set error 2013.

column_names¶

Set the "keys" that will be used in the "getline_hr" calls. If no keys (column names) are passed, it will return the current setting as a list.

"column_names" accepts a list of scalars (the column names) or a single array_ref, so you can pass the return value from "getline" too:

 $csv->column_names ($csv->getline ($fh));

"column_names" does no checking on duplicates at all, which might lead to unexpected results. Undefined entries will be replaced with the string "\cAUNDEF\cA", so

 $csv->column_names (undef, "", "name", "name");
 $hr = $csv->getline_hr ($fh);

will set "$hr->{"\cAUNDEF\cA"}" to the 1st field, "$hr->{""}" to the 2nd field, and "$hr->{name}" to the 4th field, discarding the 3rd field.

"column_names" croaks on invalid arguments.

This method does NOT work in perl-5.6.x

Parse the CSV header and set "sep", column_names and encoding.

 my @hdr = $csv->header ($fh);
 $csv->header ($fh, { sep_set => [ ";", ",", "|", "\t" ] });
 $csv->header ($fh, { detect_bom => 1, munge_column_names => "lc" });

The first argument should be a file handle.

This method resets some object properties, as it is supposed to be invoked only once per file or stream. It will leave attributes "column_names" and "bound_columns" alone if setting column names is disabled. Reading headers on previously process objects might fail on perl-5.8.0 and older.

Assuming that the file opened for parsing has a header, and the header does not contain problematic characters like embedded newlines, read the first line from the open handle then auto-detect whether the header separates the column names with a character from the allowed separator list.

If any of the allowed separators matches, and none of the other allowed separators match, set "sep" to that separator for the current CSV_XS instance and use it to parse the first line, map those to lowercase, and use that to set the instance "column_names":

 my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
 open my $fh, "<", "file.csv";
 binmode $fh; # for Windows
 $csv->header ($fh);
 while (my $row = $csv->getline_hr ($fh)) {
     ...
     }

If the header is empty, contains more than one unique separator out of the allowed set, contains empty fields, or contains identical fields (after folding), it will croak with error 1010, 1011, 1012, or 1013 respectively.

If the header contains embedded newlines or is not valid CSV in any other way, this method will croak and leave the parse error untouched.

A successful call to "header" will always set the "sep" of the $csv object. This behavior can not be disabled.

return value

On error this method will croak.

In list context, the headers will be returned whether they are used to set "column_names" or not.

In scalar context, the instance itself is returned. Note: the values as found in the header will effectively be lost if "set_column_names" is false.

Options

sep_set

 $csv->header ($fh, { sep_set => [ ";", ",", "|", "\t" ] });

The list of legal separators defaults to "[ ";", "," ]" and can be changed by this option. As this is probably the most often used option, it can be passed on its own as an unnamed argument:

 $csv->header ($fh, [ ";", ",", "|", "\t", "::", "\x{2063}" ]);

Multi-byte sequences are allowed, both multi-character and Unicode. See "sep".

detect_bom

 $csv->header ($fh, { detect_bom => 1 });

The default behavior is to detect if the header line starts with a BOM. If the header has a BOM, use that to set the encoding of $fh. This default behavior can be disabled by passing a false value to "detect_bom".

Supported encodings from BOM are: UTF-8, UTF-16BE, UTF-16LE, UTF-32BE, and UTF-32LE. BOM also supports UTF-1, UTF-EBCDIC, SCSU, BOCU-1, and GB-18030 but Encode does not (yet). UTF-7 is not supported.

If a supported BOM was detected as start of the stream, it is stored in the object attribute "ENCODING".

 my $enc = $csv->{ENCODING};

The encoding is used with "binmode" on $fh.

If the handle was opened in a (correct) encoding, this method will not alter the encoding, as it checks the leading bytes of the first line. In case the stream starts with a decoded BOM ("U+FEFF"), "{ENCODING}" will be "" (empty) instead of the default "undef".

munge_column_names

This option offers the means to modify the column names into something that is most useful to the application. The default is to map all column names to lower case.

 $csv->header ($fh, { munge_column_names => "lc" });

The following values are available:

  lc     - lower case
  uc     - upper case
  db     - valid DB field names
  none   - do not change
  \%hash - supply a mapping
  \&cb   - supply a callback

Lower case

 $csv->header ($fh, { munge_column_names => "lc" });

The header is changed to all lower-case

 $_ = lc;

Upper case

 $csv->header ($fh, { munge_column_names => "uc" });

The header is changed to all upper-case

 $_ = uc;

Literal

 $csv->header ($fh, { munge_column_names => "none" });

Hash

 $csv->header ($fh, { munge_column_names => { foo => "sombrero" });

if a value does not exist, the original value is used unchanged

Database

 $csv->header ($fh, { munge_column_names => "db" });

lower-case
all sequences of non-word characters are replaced with an underscore
all leading underscores are removed

 $_ = lc (s/\W+/_/gr =~ s/^_+//r);

Callback

 $csv->header ($fh, { munge_column_names => sub { fc } });
 $csv->header ($fh, { munge_column_names => sub { "column_".$col++ } });
 $csv->header ($fh, { munge_column_names => sub { lc (s/\W+/_/gr) } });

As this callback is called in a "map", you can use $_ directly.

set_column_names

 $csv->header ($fh, { set_column_names => 1 });

The default is to set the instances column names using "column_names" if the method is successful, so subsequent calls to "getline_hr" can return a hash. Disable setting the header can be forced by using a false value for this option.

As described in "return value" above, content is lost in scalar context.

Validation

When receiving CSV files from external sources, this method can be used to protect against changes in the layout by restricting to known headers (and typos in the header fields).

 my %known = (
     "record key" => "c_rec",
     "rec id"     => "c_rec",
     "id_rec"     => "c_rec",
     "kode"       => "code",
     "code"       => "code",
     "vaule"      => "value",
     "value"      => "value",
     );
 my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
 open my $fh, "<", $source or die "$source: $!";
 $csv->header ($fh, { munge_column_names => sub {
     s/\s+$//;
     s/^\s+//;
     $known{lc $_} or die "Unknown column '$_' in $source";
     }});
 while (my $row = $csv->getline_hr ($fh)) {
     say join "\t", $row->{c_rec}, $row->{code}, $row->{value};
     }

bind_columns¶

Takes a list of scalar references to be used for output with "print" or to store in the fields fetched by "getline". When you do not pass enough references to store the fetched fields in, "getline" will fail with error 3006. If you pass more than there are fields to return, the content of the remaining references is left untouched. Under "strict" the two should match, otherwise "getline" will fail with error 2014.

 $csv->bind_columns (\$code, \$name, \$price, \$description);
 while ($csv->getline ($fh)) {
     print "The price of a $name is \x{20ac} $price\n";
     }

To reset or clear all column binding, call "bind_columns" with the single argument "undef". This will also clear column names.

 $csv->bind_columns (undef);

If no arguments are passed at all, "bind_columns" will return the list of current bindings or "undef" if no binds are active.

Note that in parsing with "bind_columns", the fields are set on the fly. That implies that if the third field of a row causes an error (or this row has just two fields where the previous row had more), the first two fields already have been assigned the values of the current row, while the rest of the fields will still hold the values of the previous row. If you want the parser to fail in these cases, use the "strict" attribute.

eof¶

 $eof = $csv->eof ();

If "parse" or "getline" was used with an IO stream, this method will return true (1) if the last call hit end of file, otherwise it will return false (''). This is useful to see the difference between a failure and end of file.

Note that if the parsing of the last line caused an error, "eof" is still true. That means that if you are not using "auto_diag", an idiom like

 while (my $row = $csv->getline ($fh)) {
     # ...
     }
 $csv->eof or $csv->error_diag;

will not report the error. You would have to change that to

 while (my $row = $csv->getline ($fh)) {
     # ...
     }
 +$csv->error_diag and $csv->error_diag;

types¶

 $csv->types (\@tref);

This method is used to force that (all) columns are of a given type. For example, if you have an integer column, two columns with doubles and a string column, then you might do a

 $csv->types ([Text::CSV_XS::IV (),
               Text::CSV_XS::NV (),
               Text::CSV_XS::NV (),
               Text::CSV_XS::PV ()]);

Column types are used only for decoding columns while parsing, in other words by the "parse" and "getline" methods.

You can unset column types by doing a

 $csv->types (undef);

or fetch the current type settings with

 $types = $csv->types ();

IV
CSV_TYPE_IV: Set field type to integer.
NV
CSV_TYPE_NV: Set field type to numeric/float.
PV
CSV_TYPE_PV: Set field type to string.

fields¶

 @columns = $csv->fields ();

This method returns the input to "combine" or the resultant decomposed fields of a successful "parse", whichever was called more recently.

Note that the return value is undefined after using "getline", which does not fill the data structures returned by "parse".

meta_info¶

 @flags = $csv->meta_info ();

This method returns the "flags" of the input to "combine" or the flags of the resultant decomposed fields of "parse", whichever was called more recently.

For each field, a meta_info field will hold flags that inform something about the field returned by the "fields" method or passed to the "combine" method. The flags are bit-wise-"or"'d like:

0x0001
"CSV_FLAGS_IS_QUOTED": The field was quoted.
0x0002
"CSV_FLAGS_IS_BINARY": The field was binary.
0x0004
"CSV_FLAGS_ERROR_IN_FIELD": The field was invalid.
Currently only used when "allow_loose_quotes" is active.
0x0010
"CSV_FLAGS_IS_MISSING": The field was missing.

See the "is_***" methods below.

is_quoted¶

 my $quoted = $csv->is_quoted ($column_idx);

where $column_idx is the (zero-based) index of the column in the last result of "parse".

This returns a true value if the data in the indicated column was enclosed in "quote_char" quotes. This might be important for fields where content ",20070108," is to be treated as a numeric value, and where ","20070108"," is explicitly marked as character string data.

This method is only valid when "keep_meta_info" is set to a true value.

is_binary¶

 my $binary = $csv->is_binary ($column_idx);

where $column_idx is the (zero-based) index of the column in the last result of "parse".

This returns a true value if the data in the indicated column contained any byte in the range "[\x00-\x08,\x10-\x1F,\x7F-\xFF]".

This method is only valid when "keep_meta_info" is set to a true value.

is_missing¶

 my $missing = $csv->is_missing ($column_idx);

where $column_idx is the (zero-based) index of the column in the last result of "getline_hr".

 $csv->keep_meta_info (1);
 while (my $hr = $csv->getline_hr ($fh)) {
     $csv->is_missing (0) and next; # This was an empty line
     }

When using "getline_hr", it is impossible to tell if the parsed fields are "undef" because they where not filled in the "CSV" stream or because they were not read at all, as all the fields defined by "column_names" are set in the hash-ref. If you still need to know if all fields in each row are provided, you should enable "keep_meta_info" so you can check the flags.

If "keep_meta_info" is "false", "is_missing" will always return "undef", regardless of $column_idx being valid or not. If this attribute is "true" it will return either 0 (the field is present) or 1 (the field is missing).

A special case is the empty line. If the line is completely empty - after dealing with the flags - this is still a valid CSV line: it is a record of just one single empty field. However, if "keep_meta_info" is set, invoking "is_missing" with index 0 will now return true.

status¶

 $status = $csv->status ();

This method returns the status of the last invoked "combine" or "parse" call. Status is success (true: 1) or failure (false: "undef" or 0).

Note that as this only keeps track of the status of above mentioned methods, you are probably looking for "error_diag" instead.

error_input¶

 $bad_argument = $csv->error_input ();

This method returns the erroneous argument (if it exists) of "combine" or "parse", whichever was called more recently. If the last invocation was successful, "error_input" will return "undef".

Depending on the type of error, it might also hold the data for the last error-input of "getline".

error_diag¶

 Text::CSV_XS->error_diag ();
 $csv->error_diag ();
 $error_code               = 0  + $csv->error_diag ();
 $error_str                = "" . $csv->error_diag ();
 ($cde, $str, $pos, $rec, $fld) = $csv->error_diag ();

If (and only if) an error occurred, this function returns the diagnostics of that error.

If called in void context, this will print the internal error code and the associated error message to STDERR.

If called in list context, this will return the error code and the error message in that order. If the last error was from parsing, the rest of the values returned are a best guess at the location within the line that was being parsed. Their values are 1-based. The position currently is index of the byte at which the parsing failed in the current record. It might change to be the index of the current character in a later release. The records is the index of the record parsed by the csv instance. The field number is the index of the field the parser thinks it is currently trying to parse. See examples/csv-check for how this can be used.

If called in scalar context, it will return the diagnostics in a single scalar, a-la $!. It will contain the error code in numeric context, and the diagnostics message in string context.

When called as a class method or a direct function call, the diagnostics are that of the last "new" call.

_cache_diag

Note: This is an internal function only, and output cannot be relied upon. Use at own risk.

If debugging beyond what "error_diag" is able to show, the internal cache can be shown with this function.

 # Something failed ..
 $csv->error_diag;
 $csv->_cache_diag ();

record_number¶

 $recno = $csv->record_number ();

Returns the records parsed by this csv instance. This value should be more accurate than $. when embedded newlines come in play. Records written by this instance are not counted.

SetDiag¶

 $csv->SetDiag (0);

Use to reset the diagnostics if you are dealing with errors.

IMPORTS/EXPORTS¶

By default none of these are exported.

csv

 use Text::CSV_XS qw( csv );

Import the function "csv" function. See below.

:CONSTANTS

 use Text::CSV_XS qw( :CONSTANTS );

Import module constants "CSV_FLAGS_IS_QUOTED", "CSV_FLAGS_IS_BINARY", "CSV_FLAGS_ERROR_IN_FIELD", "CSV_FLAGS_IS_MISSING", "CSV_TYPE_PV", "CSV_TYPE_IV", and "CSV_TYPE_NV". Each can be imported alone

 use Text::CSV_XS qw( CSV_FLAS_IS_BINARY CSV_TYPE_NV );

FUNCTIONS¶

csv¶

This function is not exported by default and should be explicitly requested:

 use Text::CSV_XS qw( csv );

This is a high-level function that aims at simple (user) interfaces. This can be used to read/parse a "CSV" file or stream (the default behavior) or to produce a file or write to a stream (define the "out" attribute). It returns an array- or hash-reference on parsing (or "undef" on fail) or the numeric value of "error_diag" on writing. When this function fails you can get to the error using the class call to "error_diag"

 my $aoa = csv (in => "test.csv") or
     die Text::CSV_XS->error_diag;

This function takes the arguments as key-value pairs. This can be passed as a list or as an anonymous hash:

 my $aoa = csv (  in => "test.csv", sep_char => ";");
 my $aoh = csv ({ in => $fh, headers => "auto" });

The arguments passed consist of two parts: the arguments to "csv" itself and the optional attributes to the "CSV" object used inside the function as enumerated and explained in "new".

If not overridden, the default option used for CSV is

 auto_diag   => 1
 escape_null => 0

The option that is always set and cannot be altered is

 binary      => 1

As this function will likely be used in one-liners, it allows "quote" to be abbreviated as "quo", and "escape_char" to be abbreviated as "esc" or "escape".

Alternative invocations:

 my $aoa = Text::CSV_XS::csv (in => "file.csv");
 my $csv = Text::CSV_XS->new ();
 my $aoa = $csv->csv (in => "file.csv");

In the latter case, the object attributes are used from the existing object and the attribute arguments in the function call are ignored:

 my $csv = Text::CSV_XS->new ({ sep_char => ";" });
 my $aoh = $csv->csv (in => "file.csv", bom => 1);

will parse using ";" as "sep_char", not ",".

Used to specify the source. "in" can be a file name (e.g. "file.csv"), which will be opened for reading and closed when finished, a file handle (e.g. $fh or "FH"), a reference to a glob (e.g. "\*ARGV"), the glob itself (e.g. *STDIN), or a reference to a scalar (e.g. "\q{1,2,"csv"}").

When used with "out", "in" should be a reference to a CSV structure (AoA or AoH) or a CODE-ref that returns an array-reference or a hash-reference. The code-ref will be invoked with no arguments.

 my $aoa = csv (in => "file.csv");
 open my $fh, "<", "file.csv";
 my $aoa = csv (in => $fh);
 my $csv = [ [qw( Foo Bar )], [ 1, 2 ], [ 2, 3 ]];
 my $err = csv (in => $csv, out => "file.csv");

If called in void context without the "out" attribute, the resulting ref will be used as input to a subsequent call to csv:

 csv (in => "file.csv", filter => { 2 => sub { length > 2 }})

will be a shortcut to

 csv (in => csv (in => "file.csv", filter => { 2 => sub { length > 2 }}))

where, in the absence of the "out" attribute, this is a shortcut to

 csv (in  => csv (in => "file.csv", filter => { 2 => sub { length > 2 }}),
      out => *STDOUT)

out

 csv (in => $aoa, out => "file.csv");
 csv (in => $aoa, out => $fh);
 csv (in => $aoa, out =>   STDOUT);
 csv (in => $aoa, out =>  *STDOUT);
 csv (in => $aoa, out => \*STDOUT);
 csv (in => $aoa, out => \my $data);
 csv (in => $aoa, out =>  undef);
 csv (in => $aoa, out => \"skip");
 csv (in => $fh,  out => \@aoa);
 csv (in => $fh,  out => \@aoh, bom => 1);
 csv (in => $fh,  out => \%hsh, key => "key");

In output mode, the default CSV options when producing CSV are

 eol       => "\r\n"

The "fragment" attribute is ignored in output mode.

"out" can be a file name (e.g. "file.csv"), which will be opened for writing and closed when finished, a file handle (e.g. $fh or "FH"), a reference to a glob (e.g. "\*STDOUT"), the glob itself (e.g. *STDOUT), or a reference to a scalar (e.g. "\my $data").

 csv (in => sub { $sth->fetch },            out => "dump.csv");
 csv (in => sub { $sth->fetchrow_hashref }, out => "dump.csv",
      headers => $sth->{NAME_lc});

When a code-ref is used for "in", the output is generated per invocation, so no buffering is involved. This implies that there is no size restriction on the number of records. The "csv" function ends when the coderef returns a false value.

If "out" is set to a reference of the literal string "skip", the output will be suppressed completely, which might be useful in combination with a filter for side effects only.

 my %cache;
 csv (in    => "dump.csv",
      out   => \"skip",
      on_in => sub { $cache{$_[1][1]}++ });

Currently, setting "out" to any false value ("undef", "", 0) will be equivalent to "\"skip"".

If the "in" argument point to something to parse, and the "out" is set to a reference to an "ARRAY" or a "HASH", the output is appended to the data in the existing reference. The result of the parse should match what exists in the reference passed. This might come handy when you have to parse a set of files with similar content (like data stored per period) and you want to collect that into a single data structure:

 my %hash;
 csv (in => $_, out => \%hash, key => "id") for sort glob "foo-[0-9]*.csv";
 my @list; # List of arrays
 csv (in => $_, out => \@list)              for sort glob "foo-[0-9]*.csv";
 my @list; # List of hashes
 csv (in => $_, out => \@list, bom => 1)    for sort glob "foo-[0-9]*.csv";

encoding

If passed, it should be an encoding accepted by the :encoding() option to "open". There is no default value. This attribute does not work in perl 5.6.x. "encoding" can be abbreviated to "enc" for ease of use in command line invocations.

If "encoding" is set to the literal value "auto", the method "header" will be invoked on the opened stream to check if there is a BOM and set the encoding accordingly. This is equal to passing a true value in the option "detect_bom".

Encodings can be stacked, as supported by "binmode":

 # Using PerlIO::via::gzip
 csv (in       => \@csv,
      out      => "test.csv:via.gz",
      encoding => ":via(gzip):encoding(utf-8)",
      );
 $aoa = csv (in => "test.csv:via.gz",  encoding => ":via(gzip)");
 # Using PerlIO::gzip
 csv (in       => \@csv,
      out      => "test.csv:via.gz",
      encoding => ":gzip:encoding(utf-8)",
      );
 $aoa = csv (in => "test.csv:gzip.gz", encoding => ":gzip");

detect_bom

If "detect_bom" is given, the method "header" will be invoked on the opened stream to check if there is a BOM and set the encoding accordingly.

"detect_bom" can be abbreviated to "bom".

This is the same as setting "encoding" to "auto".

Note that as the method "header" is invoked, its default is to also set the headers.

headers

If this attribute is not given, the default behavior is to produce an array of arrays.

If "headers" is supplied, it should be an anonymous list of column names, an anonymous hashref, a coderef, or a literal flag: "auto", "lc", "uc", or "skip".

skip

When "skip" is used, the header will not be included in the output.

 my $aoa = csv (in => $fh, headers => "skip");

"skip" is invalid/ignored in combinations with "detect_bom".

auto

If "auto" is used, the first line of the "CSV" source will be read as the list of field headers and used to produce an array of hashes.

 my $aoh = csv (in => $fh, headers => "auto");

lc

If "lc" is used, the first line of the "CSV" source will be read as the list of field headers mapped to lower case and used to produce an array of hashes. This is a variation of "auto".

 my $aoh = csv (in => $fh, headers => "lc");

uc

If "uc" is used, the first line of the "CSV" source will be read as the list of field headers mapped to upper case and used to produce an array of hashes. This is a variation of "auto".

 my $aoh = csv (in => $fh, headers => "uc");

CODE

If a coderef is used, the first line of the "CSV" source will be read as the list of mangled field headers in which each field is passed as the only argument to the coderef. This list is used to produce an array of hashes.

 my $aoh = csv (in      => $fh,
                headers => sub { lc ($_[0]) =~ s/kode/code/gr });

this example is a variation of using "lc" where all occurrences of "kode" are replaced with "code".

ARRAY

If "headers" is an anonymous list, the entries in the list will be used as field names. The first line is considered data instead of headers.

 my $aoh = csv (in => $fh, headers => [qw( Foo Bar )]);
 csv (in => $aoa, out => $fh, headers => [qw( code description price )]);

HASH

If "headers" is a hash reference, this implies "auto", but header fields that exist as key in the hashref will be replaced by the value for that key. Given a CSV file like

 post-kode,city,name,id number,fubble
 1234AA,Duckstad,Donald,13,"X313DF"

using

 csv (headers => { "post-kode" => "pc", "id number" => "ID" }, ...

will return an entry like

 { pc     => "1234AA",
   city   => "Duckstad",
   name   => "Donald",
   ID     => "13",
   fubble => "X313DF",
   }

See also "munge_column_names" and "set_column_names".

munge_column_names

If "munge_column_names" is set, the method "header" is invoked on the opened stream with all matching arguments to detect and set the headers.

"munge_column_names" can be abbreviated to "munge".

key

If passed, will default "headers" to "auto" and return a hashref instead of an array of hashes. Allowed values are simple scalars or array-references where the first element is the joiner and the rest are the fields to join to combine the key.

 my $ref = csv (in => "test.csv", key => "code");
 my $ref = csv (in => "test.csv", key => [ ":" => "code", "color" ]);

with test.csv like

 code,product,price,color
 1,pc,850,gray
 2,keyboard,12,white
 3,mouse,5,black

the first example will return

  { 1   => {
        code    => 1,
        color   => 'gray',
        price   => 850,
        product => 'pc'
        },
    2   => {
        code    => 2,
        color   => 'white',
        price   => 12,
        product => 'keyboard'
        },
    3   => {
        code    => 3,
        color   => 'black',
        price   => 5,
        product => 'mouse'
        }
    }

the second example will return

  { "1:gray"    => {
        code    => 1,
        color   => 'gray',
        price   => 850,
        product => 'pc'
        },
    "2:white"   => {
        code    => 2,
        color   => 'white',
        price   => 12,
        product => 'keyboard'
        },
    "3:black"   => {
        code    => 3,
        color   => 'black',
        price   => 5,
        product => 'mouse'
        }
    }

The "key" attribute can be combined with "headers" for "CSV" date that has no header line, like

 my $ref = csv (
     in      => "foo.csv",
     headers => [qw( c_foo foo bar description stock )],
     key     =>     "c_foo",
     );

value

Used to create key-value hashes.

Only allowed when "key" is valid. A "value" can be either a single column label or an anonymous list of column labels. In the first case, the value will be a simple scalar value, in the latter case, it will be a hashref.

 my $ref = csv (in => "test.csv", key   => "code",
                                  value => "price");
 my $ref = csv (in => "test.csv", key   => "code",
                                  value => [ "product", "price" ]);
 my $ref = csv (in => "test.csv", key   => [ ":" => "code", "color" ],
                                  value => "price");
 my $ref = csv (in => "test.csv", key   => [ ":" => "code", "color" ],
                                  value => [ "product", "price" ]);

with test.csv like

 code,product,price,color
 1,pc,850,gray
 2,keyboard,12,white
 3,mouse,5,black

the first example will return

  { 1 => 850,
    2 =>  12,
    3 =>   5,
    }

the second example will return

  { 1   => {
        price   => 850,
        product => 'pc'
        },
    2   => {
        price   => 12,
        product => 'keyboard'
        },
    3   => {
        price   => 5,
        product => 'mouse'
        }
    }

the third example will return

  { "1:gray"    => 850,
    "2:white"   =>  12,
    "3:black"   =>   5,
    }

the fourth example will return

  { "1:gray"    => {
        price   => 850,
        product => 'pc'
        },
    "2:white"   => {
        price   => 12,
        product => 'keyboard'
        },
    "3:black"   => {
        price   => 5,
        product => 'mouse'
        }
    }

keep_headers

When using hashes, keep the column names into the arrayref passed, so all headers are available after the call in the original order.

 my $aoh = csv (in => "file.csv", keep_headers => \my @hdr);

This attribute can be abbreviated to "kh" or passed as "keep_column_names".

This attribute implies a default of "auto" for the "headers" attribute.

The headers can also be kept internally to keep stable header order:

 csv (in      => csv (in => "file.csv", kh => "internal"),
      out     => "new.csv",
      kh      => "internal");

where "internal" can also be 1, "yes", or "true". This is similar to

 my @h;
 csv (in      => csv (in => "file.csv", kh => \@h),
      out     => "new.csv",
      headers => \@h);

fragment

Only output the fragment as defined in the "fragment" method. This option is ignored when generating "CSV". See "out".

Combining all of them could give something like

 use Text::CSV_XS qw( csv );
 my $aoh = csv (
     in       => "test.txt",
     encoding => "utf-8",
     headers  => "auto",
     sep_char => "|",
     fragment => "row=3;6-9;15-*",
     );
 say $aoh->[15]{Foo};

sep_set

If "sep_set" is set, the method "header" is invoked on the opened stream to detect and set "sep_char" with the given set.

"sep_set" can be abbreviated to "seps". If neither "sep_set" not "seps" is given, but "sep" is defined, "sep_set" defaults to "[ sep ]". This is only supported for perl version 5.10 and up.

Note that as the "header" method is invoked, its default is to also set the headers.

set_column_names

If "set_column_names" is passed, the method "header" is invoked on the opened stream with all arguments meant for "header".

If "set_column_names" is passed as a false value, the content of the first row is only preserved if the output is AoA:

With an input-file like

 bAr,foo
 1,2
 3,4,5

This call

 my $aoa = csv (in => $file, set_column_names => 0);

will result in

 [[ "bar", "foo"     ],
  [ "1",   "2"       ],
  [ "3",   "4",  "5" ]]

and

 my $aoa = csv (in => $file, set_column_names => 0, munge => "none");

will result in

 [[ "bAr", "foo"     ],
  [ "1",   "2"       ],
  [ "3",   "4",  "5" ]]

csv

The function "csv" can also be called as a method or with an existing Text::CSV_XS object. This could help if the function is to be invoked a lot of times and the overhead of creating the object internally over and over again would be prevented by passing an existing instance.

 my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
 my $aoa = $csv->csv (in => $fh);
 my $aoa = csv (in => $fh, csv => $csv);

both act the same. Running this 20000 times on a 20 lines CSV file, showed a 53% speedup.

Callbacks¶

Callbacks enable actions triggered from the inside of Text::CSV_XS.

While most of what this enables can easily be done in an unrolled loop as described in the "SYNOPSIS" callbacks can be used to meet special demands or enhance the "csv" function.

error

 $csv->callbacks (error => sub { $csv->SetDiag (0) });

the "error" callback is invoked when an error occurs, but only when "auto_diag" is set to a true value. A callback is invoked with the values returned by "error_diag":

 my ($c, $s);
 sub ignore3006 {
     my ($err, $msg, $pos, $recno, $fldno) = @_;
     if ($err == 3006) {
         # ignore this error
         ($c, $s) = (undef, undef);
         Text::CSV_XS->SetDiag (0);
         }
     # Any other error
     return;
     } # ignore3006
 $csv->callbacks (error => \&ignore3006);
 $csv->bind_columns (\$c, \$s);
 while ($csv->getline ($fh)) {
     # Error 3006 will not stop the loop
     }

after_parse

 $csv->callbacks (after_parse => sub { push @{$_[1]}, "NEW" });
 while (my $row = $csv->getline ($fh)) {
     $row->[-1] eq "NEW";
     }

This callback is invoked after parsing with "getline" only if no error occurred. The callback is invoked with two arguments: the current "CSV" parser object and an array reference to the fields parsed.

The return code of the callback is ignored unless it is a reference to the string "skip", in which case the record will be skipped in "getline_all".

 sub add_from_db {
     my ($csv, $row) = @_;
     $sth->execute ($row->[4]);
     push @$row, $sth->fetchrow_array;
     } # add_from_db
 my $aoa = csv (in => "file.csv", callbacks => {
     after_parse => \&add_from_db });

This hook can be used for validation:

FAIL

Die if any of the records does not validate a rule:

 after_parse => sub {
     $_[1][4] =~ m/^[0-9]{4}\s?[A-Z]{2}$/ or
         die "5th field does not have a valid Dutch zipcode";
     }

DEFAULT

Replace invalid fields with a default value:

 after_parse => sub { $_[1][2] =~ m/^\d+$/ or $_[1][2] = 0 }

SKIP

Skip records that have invalid fields (only applies to "getline_all"):

 after_parse => sub { $_[1][0] =~ m/^\d+$/ or return \"skip"; }

before_print

 my $idx = 1;
 $csv->callbacks (before_print => sub { $_[1][0] = $idx++ });
 $csv->print (*STDOUT, [ 0, $_ ]) for @members;

This callback is invoked before printing with "print" only if no error occurred. The callback is invoked with two arguments: the current "CSV" parser object and an array reference to the fields passed.

The return code of the callback is ignored.

 sub max_4_fields {
     my ($csv, $row) = @_;
     @$row > 4 and splice @$row, 4;
     } # max_4_fields
 csv (in => csv (in => "file.csv"), out => *STDOUT,
     callbacks => { before_print => \&max_4_fields });

This callback is not active for "combine".

Callbacks for csv ()

The "csv" allows for some callbacks that do not integrate in XS internals but only feature the "csv" function.

  csv (in        => "file.csv",
       callbacks => {
           filter       => { 6 => sub { $_ > 15 } },    # first
           after_parse  => sub { say "AFTER PARSE";  }, # first
           after_in     => sub { say "AFTER IN";     }, # second
           on_in        => sub { say "ON IN";        }, # third
           },
       );
  csv (in        => $aoh,
       out       => "file.csv",
       callbacks => {
           on_in        => sub { say "ON IN";        }, # first
           before_out   => sub { say "BEFORE OUT";   }, # second
           before_print => sub { say "BEFORE PRINT"; }, # third
           },
       );

filter: This callback can be used to filter records. It is called just after a new record has been scanned. The callback accepts a:

hashref

The keys are the index to the row (the field name or field number, 1-based) and the values are subs to return a true or false value.

 csv (in => "file.csv", filter => {
            3 => sub { m/a/ },       # third field should contain an "a"
            5 => sub { length > 4 }, # length of the 5th field minimal 5
            });
 csv (in => "file.csv", filter => { foo => sub { $_ > 4 }});

If the keys to the filter hash contain any character that is not a digit it will also implicitly set "headers" to "auto" unless "headers" was already passed as argument. When headers are active, returning an array of hashes, the filter is not applicable to the header itself.

All sub results should match, as in AND.

The context of the callback sets $_ localized to the field indicated by the filter. The two arguments are as with all other callbacks, so the other fields in the current row can be seen:

 filter => { 3 => sub { $_ > 100 ? $_[1][1] =~ m/A/ : $_[1][6] =~ m/B/ }}

If the context is set to return a list of hashes ("headers" is defined), the current record will also be available in the localized %_:

 filter => { 3 => sub { $_ > 100 && $_{foo} =~ m/A/ && $_{bar} < 1000  }}

If the filter is used to alter the content by changing $_, make sure that the sub returns true in order not to have that record skipped:

 filter => { 2 => sub { $_ = uc }}

will upper-case the second field, and then skip it if the resulting content evaluates to false. To always accept, end with truth:

 filter => { 2 => sub { $_ = uc; 1 }}

coderef

 csv (in => "file.csv", filter => sub { $n++; 0; });

If the argument to "filter" is a coderef, it is an alias or shortcut to a filter on column 0:

 csv (filter => sub { $n++; 0 });

is equal to

 csv (filter => { 0 => sub { $n++; 0 });

filter-name

 csv (in => "file.csv", filter => "not_blank");
 csv (in => "file.csv", filter => "not_empty");
 csv (in => "file.csv", filter => "filled");

These are predefined filters

Given a file like (line numbers prefixed for doc purpose only):

 1:1,2,3
 2:
 3:,
 4:""
 5:,,
 6:, ,
 7:"",
 8:" "
 9:4,5,6

not_blank

Filter out the blank lines

This filter is a shortcut for

 filter => { 0 => sub { @{$_[1]} > 1 or
             defined $_[1][0] && $_[1][0] ne "" } }

Due to the implementation, it is currently impossible to also filter lines that consists only of a quoted empty field. These lines are also considered blank lines.

With the given example, lines 2 and 4 will be skipped.

not_empty

Filter out lines where all the fields are empty.

This filter is a shortcut for

 filter => { 0 => sub { grep { defined && $_ ne "" } @{$_[1]} } }

A space is not regarded being empty, so given the example data, lines 2, 3, 4, 5, and 7 are skipped.

filled

Filter out lines that have no visible data

This filter is a shortcut for

 filter => { 0 => sub { grep { defined && m/\S/ } @{$_[1]} } }

This filter rejects all lines that not have at least one field that does not evaluate to the empty string.

With the given example data, this filter would skip lines 2 through 8.

One could also use modules like Types::Standard:

 use Types::Standard -types;
 my $type   = Tuple[Str, Str, Int, Bool, Optional[Num]];
 my $check  = $type->compiled_check;
 # filter with compiled check and warnings
 my $aoa = csv (
    in     => \$data,
    filter => {
        0 => sub {
            my $ok = $check->($_[1]) or
                warn $type->get_message ($_[1]), "\n";
            return $ok;
            },
        },
    );

after_in

This callback is invoked for each record after all records have been parsed but before returning the reference to the caller. The hook is invoked with two arguments: the current "CSV" parser object and a reference to the record. The reference can be a reference to a HASH or a reference to an ARRAY as determined by the arguments.

This callback can also be passed as an attribute without the "callbacks" wrapper.

before_out

This callback is invoked for each record before the record is printed. The hook is invoked with two arguments: the current "CSV" parser object and a reference to the record. The reference can be a reference to a HASH or a reference to an ARRAY as determined by the arguments.

This callback can also be passed as an attribute without the "callbacks" wrapper.

This callback makes the row available in %_ if the row is a hashref. In this case %_ is writable and will change the original row.

on_in

This callback acts exactly as the "after_in" or the "before_out" hooks.

This callback can also be passed as an attribute without the "callbacks" wrapper.

This callback makes the row available in %_ if the row is a hashref. In this case %_ is writable and will change the original row. So e.g. with

  my $aoh = csv (
      in      => \"foo\n1\n2\n",
      headers => "auto",
      on_in   => sub { $_{bar} = 2; },
      );

$aoh will be:

  [ { foo => 1,
      bar => 2,
      }
    { foo => 2,
      bar => 2,
      }
    ]

INTERNALS¶

Combine (...)
Parse (...)

The arguments to these internal functions are deliberately not described or documented in order to enable the module authors make changes it when they feel the need for it. Using them is highly discouraged as the API may change in future releases.

EXAMPLES¶

Reading a CSV file line by line:¶

 my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
 open my $fh, "<", "file.csv" or die "file.csv: $!";
 while (my $row = $csv->getline ($fh)) {
     # do something with @$row
     }
 close $fh or die "file.csv: $!";

 my $aoa = csv (in => "file.csv", on_in => sub {
     # do something with %_
     });

Reading only a single column

 my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
 open my $fh, "<", "file.csv" or die "file.csv: $!";
 # get only the 4th column
 my @column = map { $_->[3] } @{$csv->getline_all ($fh)};
 close $fh or die "file.csv: $!";

with "csv", you could do

 my @column = map { $_->[0] }
     @{csv (in => "file.csv", fragment => "col=4")};

Parsing CSV strings:¶

 my $csv = Text::CSV_XS->new ({ keep_meta_info => 1, binary => 1 });
 my $sample_input_string =
     qq{"I said, ""Hi!""",Yes,"",2.34,,"1.09","\x{20ac}",};
 if ($csv->parse ($sample_input_string)) {
     my @field = $csv->fields;
     foreach my $col (0 .. $#field) {
         my $quo = $csv->is_quoted ($col) ? $csv->{quote_char} : "";
         printf "%2d: %s%s%s\n", $col, $quo, $field[$col], $quo;
         }
     }
 else {
     print STDERR "parse () failed on argument: ",
         $csv->error_input, "\n";
     $csv->error_diag ();
     }

Parsing CSV from memory

Given a complete CSV data-set in scalar $data, generate a list of lists to represent the rows and fields

 # The data
 my $data = join "\r\n" => map { join "," => 0 .. 5 } 0 .. 5;
 # in a loop
 my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1 });
 open my $fh, "<", \$data;
 my @foo;
 while (my $row = $csv->getline ($fh)) {
     push @foo, $row;
     }
 close $fh;
 # a single call
 my $foo = csv (in => \$data);

Printing CSV data¶

The fast way: using "print"

An example for creating "CSV" files using the "print" method:

 my $csv = Text::CSV_XS->new ({ binary => 1, eol => $/ });
 open my $fh, ">", "foo.csv" or die "foo.csv: $!";
 for (1 .. 10) {
     $csv->print ($fh, [ $_, "$_" ]) or $csv->error_diag;
     }
 close $fh or die "$tbl.csv: $!";

The slow way: using "combine" and "string"

or using the slower "combine" and "string" methods:

 my $csv = Text::CSV_XS->new;
 open my $csv_fh, ">", "hello.csv" or die "hello.csv: $!";
 my @sample_input_fields = (
     'You said, "Hello!"',   5.67,
     '"Surely"',   '',   '3.14159');
 if ($csv->combine (@sample_input_fields)) {
     print $csv_fh $csv->string, "\n";
     }
 else {
     print "combine () failed on argument: ",
         $csv->error_input, "\n";
     }
 close $csv_fh or die "hello.csv: $!";

Generating CSV into memory

Format a data-set (@foo) into a scalar value in memory ($data):

 # The data
 my @foo = map { [ 0 .. 5 ] } 0 .. 3;
 # in a loop
 my $csv = Text::CSV_XS->new ({ binary => 1, auto_diag => 1, eol => "\r\n" });
 open my $fh, ">", \my $data;
 $csv->print ($fh, $_) for @foo;
 close $fh;
 # a single call
 csv (in => \@foo, out => \my $data);

Rewriting CSV¶

Rewrite "CSV" files with ";" as separator character to well-formed "CSV":

 use Text::CSV_XS qw( csv );
 csv (in => csv (in => "bad.csv", sep_char => ";"), out => *STDOUT);

As "STDOUT" is now default in "csv", a one-liner converting a UTF-16 CSV file with BOM and TAB-separation to valid UTF-8 CSV could be:

 $ perl -C3 -MText::CSV_XS=csv -we\
    'csv(in=>"utf16tab.csv",encoding=>"utf16",sep=>"\t")' >utf8.csv

Dumping database tables to CSV¶

Dumping a database table can be simple as this (TIMTOWTDI):

 my $dbh = DBI->connect (...);
 my $sql = "select * from foo";
 # using your own loop
 open my $fh, ">", "foo.csv" or die "foo.csv: $!\n";
 my $csv = Text::CSV_XS->new ({ binary => 1, eol => "\r\n" });
 my $sth = $dbh->prepare ($sql); $sth->execute;
 $csv->print ($fh, $sth->{NAME_lc});
 while (my $row = $sth->fetch) {
     $csv->print ($fh, $row);
     }
 # using the csv function, all in memory
 csv (out => "foo.csv", in => $dbh->selectall_arrayref ($sql));
 # using the csv function, streaming with callbacks
 my $sth = $dbh->prepare ($sql); $sth->execute;
 csv (out => "foo.csv", in => sub { $sth->fetch            });
 csv (out => "foo.csv", in => sub { $sth->fetchrow_hashref });

Note that this does not discriminate between "empty" values and NULL-values from the database, as both will be the same empty field in CSV. To enable distinction between the two, use "quote_empty".

 csv (out => "foo.csv", in => sub { $sth->fetch }, quote_empty => 1);

If the database import utility supports special sequences to insert "NULL" values into the database, like MySQL/MariaDB supports "\N", use a filter or a map

 csv (out => "foo.csv", in => sub { $sth->fetch },
                     on_in => sub { $_ //= "\\N" for @{$_[1]} });
 while (my $row = $sth->fetch) {
     $csv->print ($fh, [ map { $_ // "\\N" } @$row ]);
     }

Note that this will not work as expected when choosing the backslash ("\") as "escape_char", as that will cause the "\" to need to be escaped by yet another "\", which will cause the field to need quotation and thus ending up as "\\N" instead of "\N". See also "undef_str".

 csv (out => "foo.csv", in => sub { $sth->fetch }, undef_str => "\\N");

These special sequences are not recognized by Text::CSV_XS on parsing the CSV generated like this, but map and filter are your friends again

 while (my $row = $csv->getline ($fh)) {
     $sth->execute (map { $_ eq "\\N" ? undef : $_ } @$row);
     }
 csv (in => "foo.csv", filter => { 1 => sub {
     $sth->execute (map { $_ eq "\\N" ? undef : $_ } @{$_[1]}); 0; }});

Converting CSV to JSON¶

 use Text::CSV_XS qw( csv );
 use JSON; # or Cpanel::JSON::XS for better performance
 # AoA (no header interpretation)
 say encode_json (csv (in => "file.csv"));
 # AoH (convert to structures)
 say encode_json (csv (in => "file.csv", bom => 1));

Yes, it is that simple.

The examples folder¶

For more extended examples, see the examples/ 1. sub-directory in the original distribution or the git repository 2.

 1. https://github.com/Tux/Text-CSV_XS/tree/master/examples
 2. https://github.com/Tux/Text-CSV_XS

The following files can be found there:

parser-xs.pl

This can be used as a boilerplate to parse invalid "CSV" and parse beyond (expected) errors alternative to using the "error" callback.

 $ perl examples/parser-xs.pl bad.csv >good.csv

csv-check

This is a command-line tool that uses parser-xs.pl techniques to check the "CSV" file and report on its content.

 $ csv-check files/utf8.csv
 Checked files/utf8.csv  with csv-check 1.9
 using Text::CSV_XS 1.32 with perl 5.26.0 and Unicode 9.0.0
 OK: rows: 1, columns: 2
     sep = <,>, quo = <">, bin = <1>, eol = <"\n">

csv-split

This command splits "CSV" files into smaller files, keeping (part of) the header. Options include maximum number of (data) rows per file and maximum number of columns per file or a combination of the two.

csv2xls

A script to convert "CSV" to Microsoft Excel ("XLS"). This requires extra modules Date::Calc and Spreadsheet::WriteExcel. The converter accepts various options and can produce UTF-8 compliant Excel files.

csv2xlsx

A script to convert "CSV" to Microsoft Excel ("XLSX"). This requires the modules Date::Calc and Spreadsheet::Writer::XLSX. The converter does accept various options including merging several "CSV" files into a single Excel file.

csvdiff

A script that provides colorized diff on sorted CSV files, assuming first line is header and first field is the key. Output options include colorized ANSI escape codes or HTML.

 $ csvdiff --html --output=diff.html file1.csv file2.csv

rewrite.pl

A script to rewrite (in)valid CSV into valid CSV files. Script has options to generate confusing CSV files or CSV files that conform to Dutch MS-Excel exports (using ";" as separation).

Script - by default - honors BOM and auto-detects separation converting it to default standard CSV with "," as separator.

CAVEATS¶

Text::CSV_XS is not designed to detect the characters used to quote and separate fields. The parsing is done using predefined (default) settings. In the examples sub-directory, you can find scripts that demonstrate how you could try to detect these characters yourself.

Microsoft Excel¶

The import/export from Microsoft Excel is a risky task, according to the documentation in "Text::CSV::Separator". Microsoft uses the system's list separator defined in the regional settings, which happens to be a semicolon for Dutch, German and Spanish (and probably some others as well). For the English locale, the default is a comma. In Windows however, the user is free to choose a predefined locale, and then change every individual setting in it, so checking the locale is no solution.

As of version 1.17, a lone first line with just

  sep=;

will be recognized and honored when parsing with "getline".

TODO¶

More Errors & Warnings

New extensions ought to be clear and concise in reporting what error has occurred where and why, and maybe also offer a remedy to the problem.

"error_diag" is a (very) good start, but there is more work to be done in this area.

Basic calls should croak or warn on illegal parameters. Errors should be documented.

setting meta info

Future extensions might include extending the "meta_info", "is_quoted", and "is_binary" to accept setting these flags for fields, so you can specify which fields are quoted in the "combine"/"string" combination.

 $csv->meta_info (0, 1, 1, 3, 0, 0);
 $csv->is_quoted (3, 1);

Metadata Vocabulary for Tabular Data <http://w3c.github.io/csvw/metadata/> (a W3C editor's draft) could be an example for supporting more metadata.

Parse the whole file at once

Implement new methods or functions that enable parsing of a complete file at once, returning a list of hashes. Possible extension to this could be to enable a column selection on the call:

 my @AoH = $csv->parse_file ($filename, { cols => [ 1, 4..8, 12 ]});

returning something like

 [ { fields => [ 1, 2, "foo", 4.5, undef, "", 8 ],
     flags  => [ ... ],
     },
   { fields => [ ... ],
     .
     },
   ]

Note that the "csv" function already supports most of this, but does not return flags. "getline_all" returns all rows for an open stream, but this will not return flags either. "fragment" can reduce the required rows or columns, but cannot combine them.

provider

 csv (in => $fh) vs csv (provider => sub { get_line });

Whatever the attribute name might end up to be, this should make it easier to add input providers for parsing. Currently most special variations for the "in" attribute are aimed at CSV generation: e.g. a callback is defined to return a reference to a record. This new attribute should enable passing data to parse, like getline.

Suggested by Johan Vromans.

Cookbook

Write a document that has recipes for most known non-standard (and maybe some standard) "CSV" formats, including formats that use "TAB", ";", "|", or other non-comma separators.

Examples could be taken from W3C's CSV on the Web: Use Cases and Requirements <http://w3c.github.io/csvw/use-cases-and-requirements/index.html>

Steal

Steal good new ideas and features from PapaParse <http://papaparse.com> or csvkit <http://csvkit.readthedocs.org>.

Raku support

Raku support can be found here <https://github.com/Tux/CSV>. The interface is richer in support than the Perl5 API, as Raku supports more types.

The Raku version does not (yet) support pure binary CSV datasets.

NOT TODO¶

combined methods: Requests for adding means (methods) that combine "combine" and "string" in a single call will not be honored (use "print" instead). Likewise for "parse" and "fields" (use "getline" instead), given the problems with embedded newlines.

Release plan¶

No guarantees, but this is what I had in mind some time ago:

•: DIAGNOSTICS section in pod to *describe* the errors (see below)

EBCDIC¶

Everything should now work on native EBCDIC systems. As the test does not cover all possible codepoints and Encode does not support "utf-ebcdic", there is no guarantee that all handling of Unicode is done correct.

Opening "EBCDIC" encoded files on "ASCII"+ systems is likely to succeed using Encode's "cp37", "cp1047", or "posix-bc":

 open my $fh, "<:encoding(cp1047)", "ebcdic_file.csv" or die "...";

DIAGNOSTICS¶

Still under construction ...

If an error occurs, "$csv->error_diag" can be used to get information on the cause of the failure. Note that for speed reasons the internal value is never cleared on success, so using the value returned by "error_diag" in normal cases - when no error occurred - may cause unexpected results.

If the constructor failed, the cause can be found using "error_diag" as a class method, like "Text::CSV_XS->error_diag".

The "$csv->error_diag" method is automatically invoked upon error when the contractor was called with "auto_diag" set to 1 or 2, or when autodie is in effect. When set to 1, this will cause a "warn" with the error message, when set to 2, it will "die". "2012 - EOF" is excluded from "auto_diag" reports.

Errors can be (individually) caught using the "error" callback.

The errors as described below are available. I have tried to make the error itself explanatory enough, but more descriptions will be added. For most of these errors, the first three capitals describe the error category:

INI
Initialization error or option conflict.
ECR
Carriage-Return related parse error.
EOF
End-Of-File related parse error.
EIQ
Parse error inside quotation.
EIF
Parse error inside field.
ECB
Combine error.
EHR
HashRef parse related error.

And below should be the complete list of error codes that can be returned:

1001 "INI - sep_char is equal to quote_char or escape_char"
The separation character cannot be equal to the quotation character or to the escape character, as this would invalidate all parsing rules.
1002 "INI - allow_whitespace with escape_char or quote_char SP or TAB"
Using the "allow_whitespace" attribute when either "quote_char" or "escape_char" is equal to "SPACE" or "TAB" is too ambiguous to allow.
1003 "INI - \r or \n in main attr not allowed"
Using default "eol" characters in either "sep_char", "quote_char", or "escape_char" is not allowed.
1004 "INI - callbacks should be undef or a hashref"
The "callbacks" attribute only allows one to be "undef" or a hash reference.
1005 "INI - EOL too long"
The value passed for EOL is exceeding its maximum length (16).
1006 "INI - SEP too long"
The value passed for SEP is exceeding its maximum length (16).
1007 "INI - QUOTE too long"
The value passed for QUOTE is exceeding its maximum length (16).
1008 "INI - SEP undefined"
The value passed for SEP should be defined and not empty.
1010 "INI - the header is empty"
The header line parsed in the "header" is empty.
1011 "INI - the header contains more than one valid separator"
The header line parsed in the "header" contains more than one (unique) separator character out of the allowed set of separators.
1012 "INI - the header contains an empty field"
The header line parsed in the "header" contains an empty field.
1013 "INI - the header contains nun-unique fields"
The header line parsed in the "header" contains at least two identical fields.
1014 "INI - header called on undefined stream"
The header line cannot be parsed from an undefined source.
1500 "PRM - Invalid/unsupported argument(s)"
Function or method called with invalid argument(s) or parameter(s).
1501 "PRM - The key attribute is passed as an unsupported type"
The "key" attribute is of an unsupported type.
1502 "PRM - The value attribute is passed without the key attribute"
The "value" attribute is only allowed when a valid key is given.
1503 "PRM - The value attribute is passed as an unsupported type"
The "value" attribute is of an unsupported type.
2010 "ECR - QUO char inside quotes followed by CR not part of EOL"
When "eol" has been set to anything but the default, like "\r\t\n", and the "\r" is following the second (closing) "quote_char", where the characters following the "\r" do not make up the "eol" sequence, this is an error.
2011 "ECR - Characters after end of quoted field"
Sequences like "1,foo,"bar"baz,22,1" are not allowed. "bar" is a quoted field and after the closing double-quote, there should be either a new-line sequence or a separation character.
2012 "EOF - End of data in parsing input stream"
Self-explaining. End-of-file while inside parsing a stream. Can happen only when reading from streams with "getline", as using "parse" is done on strings that are not required to have a trailing "eol".
2013 "INI - Specification error for fragments RFC7111"
Invalid specification for URI "fragment" specification.
2014 "ENF - Inconsistent number of fields"
Inconsistent number of fields under strict parsing.
2015 "ERW - Empty row"
An empty row was not allowed.
2021 "EIQ - NL char inside quotes, binary off"
Sequences like "1,"foo\nbar",22,1" are allowed only when the binary option has been selected with the constructor.
2022 "EIQ - CR char inside quotes, binary off"
Sequences like "1,"foo\rbar",22,1" are allowed only when the binary option has been selected with the constructor.
2023 "EIQ - QUO character not allowed"
Sequences like ""foo "bar" baz",qu" and "2023,",2008-04-05,"Foo, Bar",\n" will cause this error.
2024 "EIQ - EOF cannot be escaped, not even inside quotes"
The escape character is not allowed as last character in an input stream.
2025 "EIQ - Loose unescaped escape"
An escape character should escape only characters that need escaping.

Allowing the escape for other characters is possible with the attribute "allow_loose_escapes".
2026 "EIQ - Binary character inside quoted field, binary off"
Binary characters are not allowed by default. Exceptions are fields that contain valid UTF-8, that will automatically be upgraded if the content is valid UTF-8. Set "binary" to 1 to accept binary data.
2027 "EIQ - Quoted field not terminated"
When parsing a field that started with a quotation character, the field is expected to be closed with a quotation character. When the parsed line is exhausted before the quote is found, that field is not terminated.
2030 "EIF - NL char inside unquoted verbatim, binary off"
2031 "EIF - CR char is first char of field, not part of EOL"
2032 "EIF - CR char inside unquoted, not part of EOL"
2034 "EIF - Loose unescaped quote"
2035 "EIF - Escaped EOF in unquoted field"
2036 "EIF - ESC error"
2037 "EIF - Binary character in unquoted field, binary off"
2110 "ECB - Binary character in Combine, binary off"
2200 "EIO - print to IO failed. See errno"
3001 "EHR - Unsupported syntax for column_names ()"
3002 "EHR - getline_hr () called before column_names ()"
3003 "EHR - bind_columns () and column_names () fields count mismatch"
3004 "EHR - bind_columns () only accepts refs to scalars"
3006 "EHR - bind_columns () did not pass enough refs for parsed fields"
3007 "EHR - bind_columns needs refs to writable scalars"
3008 "EHR - unexpected error in bound fields"
3009 "EHR - print_hr () called before column_names ()"
3010 "EHR - print_hr () called with invalid arguments"

AUTHOR¶

Alan Citterman <alan@mfgrtl.com> wrote the original Perl module. Please don't send mail concerning Text::CSV_XS to Alan, who is not involved in the C/XS part that is now the main part of the module.

Jochen Wiedmann <joe@ispsoft.de> rewrote the en- and decoding in C by implementing a simple finite-state machine. He added variable quote, escape and separator characters, the binary mode and the print and getline methods. See ChangeLog releases 0.10 through 0.23.

H.Merijn Brand <hmbrand@cpan.org> cleaned up the code, added the field flags methods, wrote the major part of the test suite, completed the documentation, fixed most RT bugs, added all the allow flags and the "csv" function. See ChangeLog releases 0.25 and on.

COPYRIGHT AND LICENSE¶

 Copyright (C) 2007-2024 H.Merijn Brand.  All rights reserved.
 Copyright (C) 1998-2001 Jochen Wiedmann. All rights reserved.
 Copyright (C) 1997      Alan Citterman.  All rights reserved.

This library is free software; you can redistribute and/or modify it under the same terms as Perl itself.

2024-08-10

perl v5.40.0

Source file:	Text::CSV_XS.3pm.en.gz (from perl-Text-CSV_XS 1.560.0-1.1)
Source last updated:	2024-08-10T05:29:39Z
Converted to HTML:	2024-11-21T01:49:35Z

NAME¶

SYNOPSIS¶

DESCRIPTION¶

Embedded newlines¶

Unicode¶

BOM¶

SPECIFICATION¶

METHODS¶

version¶

new¶

known_attributes¶

print¶

say¶

print_hr¶

combine¶

string¶

getline¶

getline_all¶

getline_hr¶

getline_hr_all¶

parse¶

fragment¶

column_names¶

header¶

bind_columns¶

eof¶

types¶

fields¶

meta_info¶

is_quoted¶

is_binary¶

is_missing¶

status¶

error_input¶

error_diag¶

record_number¶

SetDiag¶

IMPORTS/EXPORTS¶

FUNCTIONS¶

csv¶

Callbacks¶

INTERNALS¶

EXAMPLES¶

Reading a CSV file line by line:¶

Parsing CSV strings:¶

Printing CSV data¶

Rewriting CSV¶

Dumping database tables to CSV¶

Converting CSV to JSON¶

The examples folder¶

CAVEATS¶

Microsoft Excel¶

TODO¶

NOT TODO¶

Release plan¶

EBCDIC¶

DIAGNOSTICS¶

SEE ALSO¶

AUTHOR¶

COPYRIGHT AND LICENSE¶