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.

Dynamic Hooks can call:

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

Available Events

The following are the available events:

• 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

Class level hooks

Class level hooks are defined for all the documents that relate to a class.

To create a Class level hook, let your class to extend OTriggered base class. Then define a custom property for the event you are interested on.

Below is an example to setup a hook that acts at class level against Invoice documents.

First let's create the class Invoice and the custom property on an event, e.g. onAfterCreate:

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

Let's now create the function that will be executed when the onAfterCreate event occurs. For this example we will create a Javascript function (invoiceCreated) that prints in 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' }

The following text will appear in the server console:

Invoice created: 100

Document level hook

You could need to define a special action only against one or more documents. To do this, let your class to extend OTriggered class. Then define a property for the event you are interested on, on all documents where you want the hook to be active.

For example, if you want to prevent deletion of all the documents with property account = 'Premium' in the already existing class Profile, first alter the class to set OTriggered as SUPERCLASS:

ALTER CLASS Profile SUPERCLASS OTriggered

Then use an UPDATE command to set a property with name equals to one of the available Events and value equals to the function you want to be executed when the event occurs:

UPDATE Profile SET onBeforeDelete = 'preventDeletion' WHERE account = 'Premium'

Now let's create the preventDeletion() function, e.g. in Javascript:

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

To test the hook try to delete a Premium account, e.g.:

DELETE FROM #12:1

The following Exception will be returned:

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