Grails Goodness: Custom Controller Class with Resource Annotation

In Grails we can apply the @Resource AST (Abstract Syntax Tree) annotation to a domain class. Grails will generate a complete new controller which by default extends grails.rest.RestfulController. We can use our own controller class that will be extended by the @Resource transformation. For example we might want to disable the delete action, but still want to use the @Resource transformation. We simply write a new RestfulController implementation and use the superClass attribute for the annotation to assign our custom controller as the value.

First we write a new RestfulController and we override the delete action. We return a HTTP status code 405 Method not allowed:

// File: grails-app/controllers/com/mrhaki/grails/NonDeleteRestfulController.groovy
package com.mrhaki.grails

import grails.rest.*

import static org.springframework.http.HttpStatus.METHOD_NOT_ALLOWED

/**
 * Custom RestfulController where we disable the delete action.
 */
class NonDeleteRestfulController<T> extends RestfulController<T> {

    // We need to provide the constructors, so the 
    // Resource transformation works.
    NonDeleteRestfulController(Class<T> domainClass) {
        this(domainClass, false)
    }

    NonDeleteRestfulController(Class<T> domainClass, boolean readOnly) {
        super(domainClass, readOnly)
    }

    @Override
    def delete() {
        // Return Method not allowed HTTP status code.
        render status: METHOD_NOT_ALLOWED
    }
    
}

Next we indicate in the @Resource annotation with the superClass attribute that we want to use the NonDeleteRestfulController:

// File: grails-app/domain/com/mrhaki/grails/User.groovy
package com.mrhaki.grails

import grails.rest.*

@Resource(uri = '/users', superClass = NonDeleteRestfulController)
class User {

    String username
    String lastname
    String firstname
    String email

    static constraints = {
        email email: true
        lastname nullable: true
        firstname nullable: true
    }

}

When we access the resource /users/{id} with the HTTP DELETE method we get a 405 Method Not Allowed response status code.

Written with Grails 2.4.2.