The Trigger Module¶

Trigger¶

class Trigger(**kwargs)¶

base trigger class for inheriting. Meant to be inherited on a per table basis

__init__(plpy_wrapper: plpy_wrapper.plpy_wrappers.PLPYWrapper)¶

abort()¶: skips the current event (e.g. insert,update)

after_delete()¶: run when the context is “after” and “delete”

after_insert()¶: run when the context is “after” and “insert”

after_update()¶: run when the context is “after” and “update”

before_delete()¶: run when the context is “before” and “delete”

before_insert()¶: run when the context is “before” and “insert”

before_update()¶: run when the context is “before” and “update”

execute()¶: executes the method corresponding to the trigger event and the trigger “when”. For example, if when is “BEFORE” and the event is “INSERT”, before_insert would run

overwrite_td_new()¶: must be called to persist any changes to the trigger row

Important

call this method when you’re done making all changes needed to the row otherwise changes will not be persisted

property trigger_return_val¶

returns the trigger return value as a string. This string is what the database trigger needs to return

Return type: str

TriggerContext¶

class TriggerContext(**kwargs)¶

wrapper around the TD dictionary that is available in trigger contexts documentation is taken from https://www.postgresql.org/docs/11/plpython-trigger.html This class should only be initialized in a trigger context.

__init__(TD: dict)¶

property args¶

trigger arguments If the CREATE TRIGGER command included arguments, they are available in TD["args"][0] to TD["args"][n-1].

Return type: List[str]

property event¶

the trigger event as a string. Will be one of: INSERT, UPDATE, DELETE, or TRUNCATE

Return type: str

is_changed(field_name)¶

utility method to check if a field was changed as a result of the current trigger event (e.g. update)

Return type: bool

property level¶

the trigger execution level Can be either ROW or STATEMENT

Return type: str

property name¶

the name of the running trigger

Return type: str

property old¶

the state of the row as it was before the trigger fired is None if the event is INSERT or if the trigger execution level is STATEMENT

Return type: Optional[Row]

property relid¶

the OID of the table on which the trigger occurred

Return type: int

property table_name¶

the name of the table on which the trigger occurred

Return type: str

property table_schema¶

the schema of the table on which the trigger occurred

Return type: str

property when¶

when the trigger fired is one of BEFORE, AFTER, or INSTEAD OF

Return type: str

TriggerReturnValue¶

class TriggerReturnValue¶

all possible trigger return values see https://www.postgresql.org/docs/11/plpython-trigger.html for more detail

ABORT = 'SKIP'¶

MODIFIED = 'MODIFY'¶

UNMODIFIED = 'OK'¶