Ember.js - Handlebars not recognized if required via Grunt (Node.js)

Question

is anybody else using Grunt as build tool for the Ember web application and is experiencing the same behaviour as I do? At this time, I'm using the framework in version RC3 and I can use my build tool without hassle and import all necessary libraries, uglify and compress them and everything works like a charm.

Anyhow, at least since Ember RC5 I'm not able to use Grunt for building my application anymore as Ember would not recognize Handlebars anymore!. It's always complaining that Ember Handlebars requires Handlebars version 1.0.0-rc.4. Include a SCRIPT tag in the HTML HEAD linking to the Handlebars file before you link to Ember. and right afterwards it says Cannot read property 'COMPILER_REVISION' of undefined which leads me to the assumption that Ember is not recognizing the included Handlebars library.

I haven't changed anything in my app.js (the order of the libraries/frameworks is untouched) except the references to the js files (using Ember RC5/6 instead of RC3 and Handlebars RC4 instead of RC3). But it seems that something breaks the initialization of Ember.Handlebars since then...

Do I get something wrong here? Is there a solution out there so that I can continue using Grunt as build tool?

---

EDIT

Here's my Gruntfile.js:

/*jshint camelcase: false */
/*global module:false */
module.exports = function (grunt) {

  grunt.initConfig({
    pkg: grunt.file.readJSON('package.json'),

    meta: {
      dev: {
        buildPath: '.'
      },
      prod: {
        buildPath: '.'
      }
    },

    /*
     Task for uglifyng the application javascript file in production environment
     */
    uglify: {
      options: {
        banner: '/*! <%= pkg.name %> - v<%= pkg.version %> - ' +
            '<%= grunt.template.today("yyyy-mm-dd") %> */'
      },
      prod: {
        files: [
          {
            src: '<%= meta.prod.buildPath %>/js/application.js',
            dest: '<%= meta.prod.buildPath %>/js/application.min.js'
          }
        ]

      }
    },

    /*
     Task for creating css files out of the scss files
     */
    compass: {
      prod: {
        options: {
          environment: 'production',
          noLineComments: true,
          outputStyle: 'expanded',
          cssDir: '<%= meta.prod.buildPath %>/css',
          fontsDir: '<%= meta.prod.buildPath %>/fonts',
          imagesDir: '<%= meta.prod.buildPath %>/images',
          javascriptsDir: '<%= meta.prod.buildPath %>/js'
        }
      },
      dev: {
        options: {
          environment: 'development',
          noLineComments: false,
          outputStyle: 'expanded',
          cssDir: '<%= meta.dev.buildPath %>/css',
          fontsDir: '<%= meta.dev.buildPath %>/fonts',
          imagesDir: '<%= meta.dev.buildPath %>/images',
          javascriptsDir: '<%= meta.dev.buildPath %>/js'
        }
      }
    },

    /*
     Task to minify all css files in production mode.
     All css files will end with '.min.css' instead of
     just '.css'.
     */
    cssmin: {
      minify: {
        expand: true,
        cwd: '<%= meta.prod.buildPath %>/css/',
        src: ['*.css', '!*.min.css'],
        dest: '<%= meta.prod.buildPath %>/css/',
        ext: '.min.css'
      }
    },

    /*
     Clean up the production build path
     */
    clean: {
      cssd: ['<%= meta.prod.buildPath %>/css/**/*']
    },


    /*
     A simple ordered concatenation strategy.
     This will start at app/app.js and begin
     adding dependencies in the correct order
     writing their string contents into 'application.js'

     Additionally it will wrap them in evals
     with @ sourceURL statements so errors, log
     statements and debugging will reference
     the source files by line number.

     This option is set to false for production.
     */
    neuter: {
      prod: {
        options: {
          includeSourceURL: false
        },
        files: [
          {
            src: 'app/app.js',
            dest: '<%= meta.prod.buildPath %>/js/application.js'
          }
        ]
      },
      dev: {
        options: {
          includeSourceURL: true
        },
        files: [
          {
            src: 'app/app.js',
            dest: '<%= meta.dev.buildPath %>/js/application.js'
          }
        ]
      }
    },

    /*
     Watch files for changes.

     Changes in dependencies/ember.js or application javascript
     will trigger the neuter task.

     Changes to any templates will trigger the ember_templates
     task (which writes a new compiled file into dependencies/)
     and then neuter all the files again.
     */
    watch: {
      application_code: {
        files: ['js/dependencies/ember.js', 'app/**/*.js'],
        tasks: ['neuter:dev']
      },
      compass: {
        files: [
          'styles/**/*.scss'
        ],
        tasks: ['compass:dev']
      }
    },

    /*
     Runs all .html files found in the test/ directory through PhantomJS.
     Prints the report in your terminal.
     */
    qunit: {
      all: ['test/**/*.html']
    },

    /*
     Reads the projects .jshintrc file and applies coding
     standards. Doesn't lint the dependencies or test
     support files.
     */
    jshint: {
      all: ['Gruntfile.js', 'app/**/*.js', 'test/**/*.js', '!js/dependencies/*.*', '!test/support/*.*'],
      options: {
        jshintrc: '.jshintrc'
      }
    },

    /*
     Generate the YUI Doc documentation.
     */
    yuidoc: {
      name: '<%= pkg.name %>',
      description: '<%= pkg.description %>',
      version: '<%= pkg.version %>',
      options: {
        paths: '<%= meta.dev.buildPath %>/app/',
        outdir: '<%= meta.dev.buildPath %>/yuidocs/'
      }
    },

    /*
     Find all the <whatever>_test.js files in the test folder.
     These will get loaded via script tags when the task is run.
     This gets run as part of the larger 'test' task registered
     below.
     */
    build_test_runner_file: {
      all: ['test/**/*_test.js']
    }
  });

  grunt.loadNpmTasks('grunt-contrib-uglify');
  grunt.loadNpmTasks('grunt-contrib-jshint');
  grunt.loadNpmTasks('grunt-contrib-qunit');
  grunt.loadNpmTasks('grunt-neuter');
  grunt.loadNpmTasks('grunt-contrib-watch');
  grunt.loadNpmTasks('grunt-contrib-compass');
  grunt.loadNpmTasks('grunt-contrib-clean');
  grunt.loadNpmTasks('grunt-contrib-cssmin');
  grunt.loadNpmTasks('grunt-contrib-yuidoc');

  /*
   A task to build the test runner html file that get place in
   /test so it will be picked up by the qunit task. Will
   place a single <script> tag into the body for every file passed to
   its coniguration above in the grunt.initConfig above.
   */
  grunt.registerMultiTask('build_test_runner_file', 'Creates a test runner file.', function () {
    var tmpl = grunt.file.read('test/support/runner.html.tmpl');
    var renderingContext = {
      data: {
        files: this.filesSrc.map(function (fileSrc) {
          return fileSrc.replace('test/', '');
        })
      }
    };
    grunt.file.write('test/runner.html', grunt.template.process(tmpl, renderingContext));
  });

  /*
   A task to run the application's unit tests via the command line.
   It will
   - convert all the handlebars templates into compile functions
   - combine these files + application files in order
   - lint the result
   - build an html file with a script tag for each test file
   - headlessy load this page and print the test runner results
   */
  grunt.registerTask('test', ['neuter', 'jshint', 'build_test_runner_file', 'qunit']);

  /*
   Configures all tasks which will be executed with production setup
   */
  grunt.registerTask('prod_tasks', ['clean', 'compass:prod', 'cssmin', 'neuter:prod', 'uglify:prod']);

  /*
   Setup for the production build. Sets the production build path.
   */
  grunt.registerTask('prod', 'Production Build', function () {
    grunt.task.run('prod_tasks');
  });

  /*
   Configures all tasks which will be executed with development setup
   */
  grunt.registerTask('dev_tasks', ['compass:dev', 'neuter:dev', 'watch']);

  /*
   Setup for the development build. Sets the development build path.
   */
  grunt.registerTask('dev', 'Development Build', function () {
    grunt.task.run('dev_tasks');
  });

  // Default task
  grunt.registerTask('default', 'dev');

  /*
   Configures all tasks which will be executed with doc setup
   */
  grunt.registerTask('doc_tasks', ['yuidoc']);

  /*
   Setup for the YUI doc generation.
   */
  grunt.registerTask('doc', 'Generate YuiDoc Documentation for the App', function () {
    grunt.task.run('doc_tasks');
  });

};

---

EDIT 2

I took the ember-1.0.0-rc.6.js and handlebars-1.0.0-rc.4.js files from the starter kit at the Ember.js website and tried to run the Grunt tasks on it. Here's what Chrome is telling me:

---

EDIT 3

Just in case if anybody cares, here's the link to the raised issue over at the Ember.js Github page: https://github.com/emberjs/ember.js/issues/2894

---

EDIT 4

Finally, the issue was identified to be a Handlebars inconsistency when dealing with global exports, like @Tao reported in his answer. Here's the link to the Issue on GitHub if you want to follow: https://github.com/wycats/handlebars.js/issues/539

Answer 1

It looks like this issue is being addressed in the next version of Handlebars: https://github.com/wycats/handlebars.js/issues/539 Stay tuned.

Answer 2

You have a mismatch in the version used to compile the Handlebars templates and the version included via the script tag.

If you are using grunt-contrib-handlebars, it uses the npm module handlebars to compile the the templates. The handlebars module/project is independent of Ember and has its own revisions that may or not be compatible with Ember.

To maintain compatibility with Handlebars Ember needs specific versions of handlebars which it is warning you about.

The tricky part here is you need to ensure that grunt-contrib-handlebars is forced to use that specific version of handlebars.

Solution 1: Use shrinkwrap to change grunt-contrib-handlebars's handlebars dependency version.

Solution 2: This is what I am currently using. I have switched to Emblem. The emblem grunt task asks for your handlebars file explicitly so you don't have to drop down to node sub dependency management. And your build includes the same file into your script tags, thus avoiding duplication/mismatch for future revisions.

Edit: After Gruntfile edit

Looking at the Gruntfile I don't see anything amiss. Looks like a standard build process, js -> neuter -> (if prod) -> uglify etc.

I think you need to try refreshing both emberjs and handlebars js files. Try using the files from the starter kit itself, those definitely work together.

And verify this for your index.html by looking at the unminified source in Chrome/Inspector. Handlebars has the revision numbers below the banner something like Handlebars.VERSION and Handlebars.COMPILER_REVISION. Match those with what you see in the ember.js file, somewhere below @submodule ember-handlebars-compiler in the Ember.assert.