Alex White (wu)


Wubot::Guide::Conditions - guide for using conditions in rules


There are a number of conditions that are available for the rules:

  - {fieldname} equals {value}
    - values of field {fieldname} on the message equals the specified value

  - {fieldname} matches {regexp}
    - value of field {fieldname} matches specified regexp

  - {fieldname} imatches {regexp}
    - case insensitve regexp match

  - contains {fieldname}
    - the message contains the field, the value of the field may be undefined or 0

  - {fieldname} is false
    - the field has a value that is false according to perl, i.e. undef, 0, or ""

  - {fieldname} is true
    - the field has a value which is true according to perl, i.e. not undef, 0, or ""

You can also make numeric comparisons between fields and values or fields and other fields.

  - operators: <, <=, >, >=,
    - {fieldname} {operator} {value}
    - {fieldname} {operator} {fieldname}

  - examples:
    - size > 300
    - heatindex > temperature

Any rule can be prefixed by NOT, as in:

  - NOT title matches foo
    - true unless the title contains 'foo'

You can string together multiple rules using AND and OR. You MUST capitalize the "AND" and "OR" or else the rule will not be parsed properly.

  - subject is true AND body is true
    - true if the subject and body are populated

  - title matches foo OR body matches foo
    - true if the title or body contains the string 'foo'

  - NOT title matches foo AND NOT body matches foo
    - true as long as 'foo' does not occur in either the title or body

Unfortunately you can not (yet) use parens within conditions. Conditions are evaluated from left to right in order, e.g.

  - x is true AND y is true OR z is true
    - evaluates as: x is true AND ( y is true OR z is true )

The main mechanism for nesting conditions is to use rule trees. Child rules are only evaluated if the parent rule matches, so parent and child rules are logically combined by AND. For example, set the field 'foo' to the value '1' based on the following logic:

  ( x is true OR y is true ) AND ( a is true OR b is true )

You could create the following rule tree:

    - name: check x and y
      condition: x is true OR y is true
        - name: check a and b
          condition: a is true OR b is true
          plugin: SetField
            field: foo
            value: 1