In Grails is there something in domain class like onLoad()?

问题

Guys,

I have a following domain class:

class Product { 
    String name, 
    String productRecord,

    static transients = ['productRecord']
}

productRecord is a field which is generated automatically based on the id of the Product instance.

So I've been thinking, is there a place which will be automatically called when a domain instance is load to generate the productRecord number?

What's the best way to do that?

回答1:

You can probably leverage the built-in Domain Events:

GORM supports the registration of events as methods that get fired when certain events occurs such as deletes, inserts and updates. The following is a list of supported events:

• beforeInsert - Executed before an object is initially persisted to the database
• beforeUpdate - Executed before an object is updated
• beforeDelete - Executed before an object is deleted
• beforeValidate - Executed before an object is validated
• afterInsert - Executed after an object is persisted to the database
• afterUpdate - Executed after an object has been updated
• afterDelete - Executed after an object has been deleted
• onLoad - Executed when an object is loaded from the database

Have a look at the docs for some examples.

回答2:

Typically this is done by creating a read-only getter method and put the generation logic in there. For example:

class Product { 
    String name, 
    String getProductRecord{ "Record " + id },

    static transients = ['productRecord']
}

Another example is available here.

来源：https://stackoverflow.com/questions/7453135/in-grails-is-there-something-in-domain-class-like-onload