GORM - Events

Added by Graeme Rocher, last edited by Mark Stewart on Dec 01, 2007  (view change)

GORM Events

As of Grails 1.0, GORM supports the registration of events as closures that get fired when certain events occurs such as deletes, inserts and updates. To add an event simply register the relevant closure with your domain class.

Event types

The beforeInsert event

Fired before an object is saved to the db

class Person {
   Date dateCreated

   def beforeInsert = {
       dateCreated = new Date()
   }
}

The beforeUpdate event

Fired before an existing object is updated

class Person {
   Date dateCreated
   Date lastUpdated

   def beforeInsert = {
       dateCreated = new Date()
   }
   def beforeUpdate = {
       lastUpdated = new Date()
   }
}

You must still add a nullable:true constraint to both the dateCreated and lastUpdated properties to avoid validation exceptions.

The beforeDelete event

Fired before an object is deleted.

class Person {
   String name
   Date dateCreated
   Date lastUpdated

   def beforeDelete = {
      new ActivityTrace(eventName:"Person Deleted",data:name).save()
   }
}

The onLoad event

Fired when an object is loaded from the db:

class Person {
   String name
   Date dateCreated
   Date lastUpdated

   def onLoad = {
      name = "I'm loaded"
   }
}

Automatic timestamping

The examples above demonstrated using events to update a lastUpdated and dateCreated property to keep track of updates to objects. However, this is actually not necessary. By merely defining a lastUpdated and dateCreated property these will be automatically updated for you by GORM. (Note: As above, lastUpdated is not set upon object creation so you must also add a nullable : true constraint for lastUpdated.)

If this is not the behaviour you want you can disable this feature with:

class Person {
   Date dateCreated
   Date lastUpdated
   static mapping = {
      autoTimestamp false
   }
}

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