初始化Grails 2.4.3后，LinkGenerator对象为null

Question

I am trying to generate the serverBaseUrl and then populate a field with it. I looked over quite a few instructions on how to use LinkGenerator, but I keep getting a null pointer exception on the LinkGenerator Object.

What I am working with:

import org.codehaus.groovy.grails.web.mapping.LinkGenerator

MyService{
    def linkGenerator

    String client_url = getServerUrl()

    String getServerUrl(){
        linkGenerator.serverBaseURL
    }
}

I have tried using LinkGenerator linkGenerator, relocating it, and adding a value to grails.serverURL in Config.groovy. The string client_url is on a trigger, so the method does not get called until after the program is running.

I am using Grails 2.4.3 and Java 1.8

Answer 1

The bean is actually called grailsLinkGenerator , so you need to declare it as LinkGenerator grailsLinkGenerator (or def grailsLinkGenerator ).

I couldn't find the official documentation for it, but check for example http://mrhaki.blogspot.de/2012/01/grails-goodness-generate-links-outside.html .

Answer 2

There are a couple of problems with your approach. One is that you probably want to access the grailsLinkGenerator bean.

 class MyService {
      def grailsLinkGenerator

       String getServerUrl(){
           grailsLinkGenerator.serverBaseURL
      }
 }

In your code you have this:

class MyService{
    def linkGenerator

    String client_url = getServerUrl()

    String getServerUrl(){
        linkGenerator.serverBaseURL
    }
}

Aside from the bean name problem, yo uare trying to initialize client_url before dependency injection has happened. It isn't clear why you need that property to begin with but if you really do want something like that, try this...

import org.springframework.beans.factory.InitializingBean

class MyService implements InitializingBean {
    def grailsLinkGenerator
    String client_url

    String getServerUrl(){
        grailsLinkGenerator.serverBaseURL
    }

    void afterPropertiesSet() {
        client_url = getServerUrl()
    }
}

I hope that helps.