Proper Layer files when using Dojo with Zend Framework

During my Dojo and ZF webinar on Wednesday, Pete Higgins of Dojo fame noted that I could do something different and better on one of my slides.

This particular item had to do with how I was consuming custom Dojo build layers within my code. I contacted him afterwards to find out what he suggested, and did a little playing of my own, and discovered some more Dojo and javascript beauty in the process.

The code in question looked like this:


Zend_Dojo::enableView($view);
$view->dojo()->setDjConfigOption('usePlainJson', true)
             // ->setDjConfigOption('isDebug', true)
             ->addStylesheetModule('dijit.themes.tundra')
             ->addStylesheet('/js/dojox/grid/_grid/tundraGrid.css')
             ->setLocalPath('/js/dojo/dojo.js')
             ->addLayer('/js/paste/main.js')
             // ->addLayer('/js/paste/paste.js')
             ->registerModulePath('../paste', 'paste')
             ->addJavascript('paste.main.init();')
             ->disable();

The lines he was commenting onwere the addLayer() lines.

As noted in my webinar, layers, or custom builds, are a fantastic feature of Dojo. Dojo is incredibly modular, and acts in many ways like a good server-side library should -- only include what is needed, and when its needed. The problem comes at deployment: the user suddenly experiences a situation where the application is making dozens of requests back to the server to get what it needs. The solution is to create a custom build, which pulls in all dependencies into a single file, inters any templates, and then does minification heuristics on the code prior to stripping all whitespace and compressing it. Once done, you now have a single, small file that needs to load on the request -- making the final deployed application snappy.

When I displayed this during the webinar, I noted that after doing so, you have to change your code to point at the new build -- and that's what the two lines I pointed out are for. In essence, one is for development, the other for production. Of course, this is just ripe for problems -- you forget to switch comments in production, or accidently re-merge the development version, etc.

Pete showed me another solution that was much more elegant, and which also got rid of another line in that solution above, the addJavascript()

The solution is to write your code in the same layer file as you'll compile to. When doing so, you can put all your dojo.require() statements in the file, as well as mixin any code you want in the main module namespace:


dojo.provide(\"paste.layer\");

/* Dojo modules to require... */
dojo.require(\"dijit.layout.ContentPane\");
/* ... */

/* onLoad actions to perform... */
dojo.addOnLoad(function() {
    paste.upgrade(); 
});

/* mixin functionality to the \"paste\" namespace: */
dojo.mixin(paste, {
    /* paste.newPasteButton() */
    newPasteButton:  function() {
        var form = dijit.byId(\"pasteform\");
        if (form.isValid()) {
            form.submit(); 
        }
    },
    
    /* ... */
});

In my original code, I had a "paste.main.init" method that performed all my dojo.require and dojo.addOnLoad statements, but these now can be simply a part of the layer -- eliminating more work for me.

Then, when creating the profile, you simply have it create the layer in the same file -- in this case, paste/layer.js -- but also have it create a dependency on the original layer file. The compiler will ensure that the original code gets slurped into the build. As an example:


dependencies = {
    layers: [
        {
            name: \"../paste/layer.js\",
            dependencies: [
                \"paste.layer\",
                /* other dependencies...*/
            ]
        },
    ],
    prefixes: [
        [ \"paste\", \"../paste\" ],
        /* other prefixes -- dijit, etc. */
    ]
}

This changes the original ZF snippet above to simply:


Zend_Dojo::enableView($view);
$view->dojo()->setDjConfigOption('usePlainJson', true)
             // ->setDjConfigOption('isDebug', true)
             ->addStylesheetModule('dijit.themes.tundra')
             ->addStylesheet('/js/dojox/grid/_grid/tundraGrid.css')
             ->setLocalPath('/js/dojo/dojo.js')
             ->addLayer('/js/paste/layer.js')
             ->registerModulePath('../paste', 'paste')
             ->disable();

Not much shorter -- but because I no longer need to worry about changing the file name, I can rest easier at night.

I'll be blogging more tips such as these in the coming weeks, to help support the new Dojo integration in Zend Framework.

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