Wednesday, April 30, 2014

Launching Spring Boot in Groovy with Grab

Since launch of Spring Boot I was wondering why it needs separate CLI, especially for Groovy where there is already Grab. Of course CLI provides some additional features, like reloading and out of the box dependencies, but why no one runs Boot with vanilla Groovy? So I tried it myself, and it looks like problem is that there is conflict with default Groovy libs, because standard installation includes servlet-api-2.4.jar which does not work with current Tomcat or Jetty, and as there is no anything like fork mode in Grails, there is only one way to avoid it - not to load this jar (delete it or use custom load conf).

Otherwise this works fine for me:

import org.springframework.boot.SpringApplication
import org.springframework.boot.autoconfigure.EnableAutoConfiguration
import org.springframework.web.bind.annotation.*

class ThisWillActuallyRun {

  String home() {
    "Hello World!"
}, args)

Tuesday, April 15, 2014

IllegalStateException Method on class was used outside of a Grails application

After upgrade to 2.3 and running Geb functional UI tests, they started to fail with error:

java.lang.IllegalStateException: Method on class [my.Test] was used outside of a Grails application. If running in the context of a test using the mocking API or bootstrap Grails correctly.
       at my.Test.currentGormStaticApi(Test.groovy)
       at my.Test.$static_methodMissing(Test.groovy)
       at org.codehaus.groovy.reflection.CachedMethod.invoke(
       at groovy.lang.MetaClassImpl.invokeStaticMissingMethod(
       at groovy.lang.MetaClassImpl.invokeStaticMethod(
       at groovy.lang.ExpandoMetaClass.invokeStaticMethod(
       at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(

After some pretty painful investigation, I found out that problem is when running tests with new fork mode properties, and is easy to solve by removing these options from BuildConfig.groovy:

grails.project.fork = [
    test: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256, daemon:true],
    run: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256, forkReserve:false],
    war: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256, forkReserve:false],
    console: [maxMemory: 768, minMemory: 64, debug: false, maxPerm: 256]

Thursday, April 3, 2014

MeteorJS like application in Grails

MeteorJS is new web framework that combines server-side and client-side programming into one, leaving mostly just client-side. I am defenitely not expert with tool and just seen demo on their homepage, but WOW effect is sure impressive. It suppose to kill all Rails and server-side development in general. Thank god I am full-stack developer, but anyway I am scared.

General idea behind this framework is autogenerating all server-side code, leaving mostly just configuration. Similar feature was recently introduced in Grails, so I was wondering - is it possible to create something similar to MeteorJS in Grails. And there is my experience.

Basically, it needs autogenerated REST, Javascript ORM and server push. REST is Grails feature since version 2.3; for client-side ORM I picked CanJS as it looks most similar to Meteor; for server push in Grails I picked spring-websocket plugin (because it is first result in Google, why else?). Unfortunately, spring-websocket is M1 and it relies on Spring 4, so Grails is 2.4M1 too, so it is not production safe, but MeteorJS is 0.8.0 now too, so we are even.

Application idea is simple TODO app. You can find full source here. There is defenitely some boilerplate code as it is not plugin, but I think in general it is pretty similar to MeteorJS example. It consists of 3 meaningful components: view, controller and domain object.

View is Mustache template, and is pretty straightforward if you are familiar with CanJS:

    <td>{{description}}</td><td><input type="checkbox" can-value="done"></td>
    <td><input type="button" value="Delete" can-click="delete"></td>

<input type="text" can-value="description">
<input type="button" can-click="add" value="Add">

Controller is CanJS component with ORM definition:

var Todo = can.Model({
  findAll: function(id)   {return $.get('/grails-meteor-example/todos.json/')},
  findOne: function(id)   {return $.get('/grails-meteor-example/todos.json/'+id)},
  create:  function(data) {return $.post('/grails-meteor-example/todos.json/', data)},
  update:  function(id)   {return $.ajax({type: 'PUT',    url: '/grails-meteor-example/todos.json/'+id })},
  destroy: function(id)   {return $.ajax({type: 'DELETE', url: '/grails-meteor-example/todos/'+id, contentType: 'application/json' })}
}, {});

  tag: "todos",
  template: can.view("todos.mustache"),
  scope: {
    todos: new Todo.List({}),
    description: can.compute(''),
    add: function() {
      new Todo({'description':this.description(), 'done':false}).save();
    delete: function(todo) {
  events: {
    "{todo} change": function(){
      this.scope.attr('todos', new Todo.List({}));

$(document).ready(function() {
  $("body").html( can.view.mustache("<todos></todos>"));

Domain is Grails domain object mapped as REST controller:

package org.grmeteor


class Todo {
  String description
  boolean done

View is totally similar to MeteorJS. Controller is similar, but also contains ORM definition and server push event. Both could be easily autogenerated with Grails plugin, but at least push can be also left for practical applications (probably, you will not want to have notification with millions of parallel users). Domain is pure Grails overhead, but it would probably still be needed for SQL backends in MeteorJS (and hey, those server-side devs want to eat too!).

Of course there are other files too, like server push sender and client side HTML container for CanJS, but these are mostly static and sure can be easily hidden by plugin. So only part that is missing to make Grails MeteorJS-cool is plugin itself, which even if not for practical cases could be nice to have for WOW effect and MVPs.

Wednesday, April 2, 2014

Grails REST redirect after DELETE with jQuery

If you do delete from AJAX request (directly or via framework), sometimes Grails REST controller redirects response to index method, which when done with DELETE method leads to 405 HTTP error.
This happens because of incorrect content type in request. To fix it, contentType needs to be explicitly set in request, like:

    url: '/todos/'+id,
    type: 'DELETE',
    contentType: 'application/json'