Dynamic Hooks

Dynamic Hooks are more flexible than Java Hooks because they can be changed at run-time and can run per document if needed, but are slower than Java Hooks. Look at Hooks for more information.

To execute hooks against your documents, let your classes extend the OTriggered base class. Then define a custom property for the event you're interested in. The available events are:

• onBeforeCreate, called before creating a new document
• onAfterCreate, called after creating a new document
• onBeforeRead, called before reading a document
• onAfterRead, called after reading a document
• onBeforeUpdate, called before updating a document
• onAfterUpdate, called after updating a document
• onBeforeDelete, called before deleting a document
• onAfterDelete, called after deleting a document

Dynamic Hooks can call:

• Functions written in SQL, Javascript, or any other language supported by OrientDB and the JVM
• Java static methods

Class level hooks

Class level hooks are defined for all the documents that relate to a class. Below is an example to setup a hook that acts at the class level against Invoice documents.

CREATE CLASS Invoice EXTENDS OTriggered
ALTER CLASS Invoice CUSTOM onAfterCreate=invoiceCreated

Now let's create the function invoiceCreated in Javascript that prints on the server console the invoice number created.

CREATE FUNCTION invoiceCreated "print('\\nInvoice created: ' + doc.field('number'));" LANGUAGE Javascript

Now try the hook by creating a new Invoice document.

INSERT INTO Invoice CONTENT { number: 100, notes: 'This is a test' }

And this will appear in the server console:

Invoice created: 100

Document level hook

If you need to define a special action against only one or more documents let your class extend the OTriggered class.

Example: To execute a trigger, as a Javascript function, against an existing Profile class, for all the documents with property account = 'Premium'. The trigger will be called to prevent deletion of documents:

ALTER CLASS Profile SUPERCLASS OTriggered
UPDATE Profile SET onBeforeDelete = 'preventDeletion' WHERE account = 'Premium'

And now let's create the preventDeletion() Javascript function.

CREATE FUNCTION preventDeletion "throw new java.lang.RuntimeException('Cannot delete Premium profile ' + doc)" LANGUAGE Javascript

And now test the hook by trying to delete a Premium account.

DELETE FROM #12:1

java.lang.RuntimeException: Cannot delete Premium profile profile#12:1{onBeforeDelete:preventDeletion,account:Premium,name:Jill} v-1 (<Unknown source>#2) in <Unknown source> at line number 2