如何从gsp调用Grails服务？

Question

How can I invoke a service directly from a view? I'm trying with ${my.domain.service.method} , but it complains it can't find the property.

And no, I don't want to use a controller because the view is a template.

Answer 1

Best to use the tag library because creating a service instance directly in the view via the class loader WILL NOT autowire other services declared that may live in the service you are trying to use.

Using the tag library you will have auto-wiring of those services.

In your gsp view <g:customTag param1="$modelObjec" param2="someString" />

In your taglib folder ( yourApp/grails-app/taglib/com/something/MyAppTagLib ):

package com.something

class MyAppTagLib {

    def myService  // This will be auto-wired

    def customTag = { attribs ->
        def modelObj = attribs['param1']
        def someString = attribs['param2']

        // Do something with the params

        myService.method()

        out << "I just used method of MyService class"
    }
}

Your MyService:

package com.something

class MyService {

def anotherService // This will be auto-wired

def method() {
    anotherService.anotherMethod()
}

}

Answer 2

Try this - much helpful

%{--Use BlogService--}%
<g:set var="blog" bean="blogService"/>

<ul>
    <g:each in="${blog.allTitles()}" var="title">
        <li>${title}</li>
    </g:each>
</ul>

Refer this

Also this is not a recommened thing, you can always use taglib

Answer 3

I think the best way of doing it is:

<%
    def myService = grailsApplication.mainContext.getBean("myService");
%>

This way, you get the service instance without losing the autowired services.

Answer 4

<%@ page import="com.myproject.MyService" %>
<%
    def myService = grailsApplication.classLoader.loadClass('com.myproject.MyService').newInstance()
%>

And then you can call ${myService.method()} in your gsp view

Be aware that calling transactional service methods from views hurts performance. Better to move all your transactional service method calls to the controller (if you can)