46.5. Trigger Functions

46.5. Trigger Functions
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46.5. Trigger Functions #

+ When a function is used as a trigger, the dictionary + TD contains trigger-related values: +

TD["event"]: + contains the event as a string: + INSERT, UPDATE, + DELETE, or TRUNCATE. +
TD["when"]: + contains one of BEFORE, AFTER, or + INSTEAD OF. +
TD["level"]: + contains ROW or STATEMENT. +
TD["new"] TD["old"]: + For a row-level trigger, one or both of these fields contain + the respective trigger rows, depending on the trigger event. +
TD["name"]: + contains the trigger name. +
TD["table_name"]: + contains the name of the table on which the trigger occurred. +
TD["table_schema"]: + contains the schema of the table on which the trigger occurred. +
TD["relid"]: + contains the OID of the table on which the trigger occurred. +
TD["args"]: + If the CREATE TRIGGER command + included arguments, they are available in TD["args"][0] to + TD["args"][n-1]. +

+ If TD["when"] is BEFORE or + INSTEAD OF and + TD["level"] is ROW, you can + return None or "OK" from the + Python function to indicate the row is unmodified, + "SKIP" to abort the event, or if TD["event"] + is INSERT or UPDATE you can return + "MODIFY" to indicate you've modified the new row. + Otherwise the return value is ignored. +

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