Lookup Trigger

Lookup trigger manipulates with the content of the lookup.

It means that it can add (set), increment (add), decrement (sub) and remove (delete) an entry in the lookup.

The entry is identified by a key, which is a unique primary key.

Example of the trigger that adds an entry to the lookup user_list:

 trigger:
  - lookup: user_list
    key: !ITEM EVENT user.name
    set:
      event.created: !NOW
      foo: bar

Example of the trigger that removes an entry from the lookup user_list:

 trigger:
  - lookup: user_list
    delete: !ITEM EVENT user.name

Example of the trigger that increments a counter (field my_counter) in the entry of the lookup user_list:

 trigger:
  - lookup: user_list
    key: !ITEM EVENT user.name
    add: my_counter

Example of the trigger that decrements a counter (field my_counter) in the entry of the lookup user_list:

 trigger:
  - lookup: user_list
    key: !ITEM EVENT user.name
    sub: my_counter

For both add and sub, the counter field name can be omitted. Hence the default attribute _counter will be used implicitly:

 trigger:
  - lookup: user_list
    key: !ITEM EVENT user.name
    sub:

If the counter field does not exist, it is created with the default value of 0.

!! note

Lookup entries can be accessed from the declarative expressions by `!LOOKUP.GET` and `!LOOKUP.CONTAINS` entries.