Check Syntax¶

Stored in the metakey check/condition to validate data is:

(IF-condition) ? (THEN-condition) : (ELSE-condition) where the ELSE-condition is optional

Condition: Key Operation `('String' | '1234.56' | Key | '')`

Operations: !=, ==, <, <=, =>, >, :=, where:

• := is used to set a key value
• others are for comparison as in C

Testing if Key exists¶

(! a/key) evaluates to true if the key a/key doesn't exist, to false if it exists.

Assign Syntax¶

(IF-condition) ? ('ThenValue') : ('ElseValue')

Depending on if the condition is met, either 'ThenValue' or 'ElseValue' will be assigned as key value if the metakey assign/condition is used.

Experimental: Nested Conditions¶

Multiple conditions can be nested and combined using parentheses and && (logical AND) or || (logical OR). Additional parentheses must be used to form valid conditions again. ( (condition 1) && (condition 2) )

Valid Suffix¶

The condition/validsuffix can be used to define a list of valid suffixes to numeric values. If two operants have the same valid suffix or one of them no suffix they will be treated by their numeric value ignoring their suffix. `condition/validsuffix = 'm', 'cm', 'km'would treat2.3mjust as the numeric value2.3` when comparing to another value having the same or no suffix.

Keynames¶

Keynames are all either relative to to-be-tested key (starting with ./ or ../), relative to the parentkey (starting with @/) or absolute (e.g. system/key).

Multiple Statements¶

It's also possible to test multiple conditions using check/condition/{any,all,none} as a meta array. Where any means that at least one statement has to evaluate to true, all that all statements have to evaluate to true, and none that no statement is allowed to evaluate to false (default). For multiple assign statements use assign/condition as a meta array. The first assign/condition/# statement that evaluates to true will be assigned and the rest ignored.

Example¶

(this/key  != 'value') ? (then/key == some/other/key) : (or/key <= '125')

Meaning: IF this/key NOT EQUAL TO `'value'THENthen/keyMUST EQUALsome/other/keyELSEor/keyMUST BE LESS THAN125`

Another full example:

#Backup-and-Restore:/examples/conditionals
sudo kdb mount conditionals.dump /examples/conditionals conditionals dump
kdb set /examples/conditionals/fkey 3.0
kdb set /examples/conditionals/hkey hello
# will succeed
kdb setmeta user/examples/conditionals/key check/condition "(../hkey == 'hello') ? (../fkey == '3.0')"
# will fail
kdb setmeta user/examples/conditionals/key check/condition "(../hkey == 'hello') ? (../fkey == '5.0')"
# RET:5
# ERRORS:135

Assignment example:

kdb set user/examples/conditionals/hkey Hello
kdb setmeta user/examples/conditionals/hkey assign/condition "(./ == 'Hello') ? ('World')"
# alternative syntax: "(../hkey == 'Hello') ? ('World')
kdb get user/examples/conditionals/hkey
#> World
# cleanup
kdb rm -r /examples/conditionals
sudo kdb umount /examples/conditionals

Global plugin example:

``` sudo kdb mount main.ini /examples/conditionals ni sudo kdb mount sub.ini /examples/conditionals/sub ini