Triggers

Overview

A trigger is a mechanism that automatically executes predefined operations in response to specific events on nodes or edges. Triggers can be set to run before or after events such as insertion, update, upsert, or deletion of data. They allow you to enforce business rules, maintain data integrity, or perform auxiliary operations without manual intervention, ensuring that logic tied to DML operations is executed consistently and automatically.

Ultipa supports 8 trigger types:

Timing	Events
`BEFORE`	`INSERT`, `SET`, `UPSERT`, `DELETE`
`AFTER`	`INSERT`, `SET`, `UPSERT`, `DELETE`

BEFORE triggers can modify data and block operations.
AFTER triggers execute after the data is written and cannot modify the written data.

Showing Triggers

To show triggers in the current graph:

GQL
SHOW TRIGGER

To show node triggers in the current graph:

GQL
SHOW NODE TRIGGER

To show edge triggers in the current graph:

GQL
SHOW EDGE TRIGGER

Each trigger provides the following essential metadata:

Field	Description
`name`	The name of the trigger.
`schema`	The name of node or edge schema to which the trigger applies.
`description`	The comment given to the trigger.
`timing`	When the trigger takes effect — either `before` or `after` the event.
`event`	The type of event that activates the trigger, including `insert`, `set` (update), `upsert`, and `delete`.
`call`	The operation or logic executed by the trigger.

Creating Trigger

To create a trigger AutoUpperCase for Student nodes that converts the name property to uppercase before insertion:

GQL
CREATE TRIGGER "AutoUpperCase" ON NODE "Student" 
COMMENT "Converts name to uppercases before insertion" 
BEFORE INSERT CALL "
  $entity CALL {
    LET entity.name = upper(entity.name)
  }
"

This trigger automatically converts the name property of a Student node to uppercase before insertion:

GQL
INSERT (n:Student {name: "John Doe"}) RETURN n.name

Result:

n.name
JOHN DOE

To create a trigger AutoStaus for ENROLLED_IN edges, automatically setting the status property to "active" before insertion:

GQL
CREATE TRIGGER "AutoStaus" ON EDGE "ENROLLED_IN"
COMMENT "Sets status to true"
BEFORE INSERT CALL "
  $entity CALL {
    LET entity.status = 'active'
  }
"

This trigger automatically sets the status property of an ENROLLED_IN edge to "active" before insertion:

GQL
MATCH (s:Student {name: "JOHN DOE"}), (c:Course {name: "Science"})
INSERT (s)-[e:ENROLLED_IN]->(c)
RETURN e.status

Result:

e.status
active

Dropping Trigger

To drop the node trigger AutoUpperCase:

GQL
DROP NODE TRIGGER AutoUpperCase

To drop the edge trigger AutoStaus:

GQL
DROP EDGE TRIGGER AutoStaus

Note: Dropping a node or edge schema will also remove any triggers associated with that schema.