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Contents Prerequisites Generating Output with meta Generating a Custom Bootstrap Enabling Wildcard Support in requires Exporting Loader Paths Resolving Relative Paths with -base-path Changing the Format Exporting Filenames Exporting Definitions

Generating Metadata

The metadata tracked by the Sencha Cmd compiler has a variety of uses, some of which we will examine in this guide. To support these uses, the compiler can export and format this metadata in several different ways, which we will cover here as well.

Prerequisites

The following guides are recommended reading before proceeding further:

Generating Output with meta

One of the major new dimensions provided by the compiler is its ability to export metadata in various formats. This feature is used to produce the ext.js “bootstrap” file that contains various classes and a block of metadata about all of the files in the framework.

There are several forms of metadata that the compiler can export using the meta command:

  • Class aliases
  • Alternate class names
  • Loader paths
  • Filenames
  • Definitions

Generating a Custom Bootstrap

Note. This process is handled automatically for applications generated by Sencha Cmd. If you are not using Sencha Cmd generated application, this section describes how to achieve the same results manually.

The primary use for the meta command is to create your own “bootstrap” file. This file gives the framework the same level of awareness of your application code that it has of the framework code itself.

The simplest way to manage your bootstrap file is to store it alongside your markup file. If that won’t work for you, read on to see how to manage relative paths. If you have your markup file in a source folder in your classpath, you need to tell the compiler to ignore the bootstrap file. Do this using the -ignore switch:

sencha compile -classpath=sdk/src,app -ignore bootstrap.js \
    ...

Enabling Wildcard Support in requires

The end of "ext-debug.js" contains these two function calls:

Ext.ClassManager.addNameAlternateMappings({
    "Ext.draw.engine.ImageExporter": [],
    "Ext.layout.component.Auto": [],
    ...
});

Ext.ClassManager.addNameAliasMappings({
    "Ext.draw.engine.ImageExporter": [],
    "Ext.layout.component.Auto": [
        "layout.autocomponent"
    ],
    ...
});

It is the presence of these two pieces of metadata that allow wildcards to be used in requires statements. That is:

Ext.define('MyApp.App', {
    requires: [
        'Ext.grid.*'
    ],
    ...
});

All that is required to use wildcards in your own code is to provide the same bootstrap data for your app.

This command will produce a file that does just that:

sencha compile -classpath=app \
    meta -alias -out bootstrap.js and \
    meta -alt -append -out bootstrap.js

The above command line tells the compiler to read in the source in the app folder and generate two pieces of metadata. The second piece of metadata is written to the same output file as the first, but using the -append option to append to the file and not replace it.

Once you have the "bootstrap.js" file, change your page like so to add it to the x-bootstrap section:

<html>
    <head>
        <!-- <x-compile> -->
            <!-- <x-bootstrap> -->
                <script src="../sdk/ext-dev.js" type="text/javascript"></script>

                <script src="bootstrap.js" type="text/javascript"></script>
            <!-- </x-bootstrap> -->

            <script src="app/app.js" type="text/javascript"></script>
        <!-- </x-compile> -->
    </head>
    <body></body>
</html>

The "bootstrap.js" file needs to be regenerated if you do any of the following:

  • Add a class
  • Remove a class
  • Change class aliases
  • Change class alternate names

This rebuild of the bootstrap data can be handled in a variety of ways, but the fundamental question is whether to keep these files in source control or require developers to generate them locally. Both approaches work and can be automated to some degree.

Note. For applications generated by Sencha Cmd, this is handled as part of the build process of sencha app build. Alternatively, refreshing just the bootstrap instead of performing a full build is accomplished by the sencha app refresh command.

Exporting Loader Paths

In large applications it can be helpful to organize your namespace using multiple source trees. In fact, Ext JS itself uses three source trees. This approach, however, has always presented problems for the dynamic loader requiring loader paths to be configured by hand to work around the issue. The compiler, however, has complete knowledge of class-to-file relationships given all of the source in the classpath. And the meta command can export that data for use in your application.

If you are already sold on the above to create a "bootstrap.js", this data can be added by adding one more meta command (of course, the classpath will contain multiple folders in this case):

sencha compile -classpath=src1,src2,src3 \
    meta -alias -out bootstrap.js and \
    meta -alt -append -out bootstrap.js and \
    meta -loader -append -out bootstrap.js

Now the "bootstrap.js" file solves both problems. With this approach, the following things will also require you to rebuild "bootstrap.js":

  • Rename a file or folder
  • Reorganize the classpath
  • Reorganize the content of any of the source trees

Note. This part is also handled automatically for applications generated by Sencha Cmd.

Resolving Relative Paths with -base-path

For many good reasons, paths need to be relative. Whenever you deal with relative paths, however, you need to solve the problem of where those relative paths are based. In the above examples we cheated a bit and placed the "bootstrap.js" file next to the markup file. This leverages the fact that the meta command defaults the base folder to the location of the output file.

When this is not the case, you need to tell the meta command the base for determining relative paths. Let’s say we want to move the "bootstrap.js" file in to the "build" folder (perhaps because we are not keeping it in source control). Since our page is in the current folder and our source is in the "app" folder, this will generate the proper relative paths:

sencha compile -classpath=src1,src2,src3 \
    meta -alias -out build/bootstrap.js and \
    meta -alt -append -out build/bootstrap.js and \
    meta -loader -append -base-path . -out build/bootstrap.js

Since the -alias and -alt modes do not deal in paths, the -base-path option is only needed on the -loader use of the meta command.

Changing the Format

By default, the meta command exports metadata in JSONP format using a function call wrapper appropriate for the type of metadata requested. If a different function call is desired or you want the data in JSON format, you can request this in the meta command.

In the example below, the aliases.json file will contain the alias data in JSON format. You cannot use -append in this case because JSON format requires a single, top-level object or array.

sencha compile -classpath=src1,src2,src3 \
    meta -alias -json -out aliases.json

In this next example, we customize the JSONP wrapping by supplying the function to call:

sencha compile -classpath=src1,src2,src3 \
    meta -alias -jsonp Foo.bar.doAliases -out aliases.js

This form can work with -append because it produces JavaScript code. The output of the above looks roughly like this:

Foo.bar.doAliases(
    // ... the JSON data ...
);

Exporting Filenames

An occasionally useful form of metadata supported by the meta command is filename data. That is, the list of a files in the proper, dependency order. In many ways this is the same as the other meta data forms in that this data can be exported in JSON or JSONP format, and can be combined using -append.

The first difference with -filenames is that the default format is text. To produce JSON or JSONP, you must specify one of the -json or -jsonp options.

In the default mode of text, the filenames are written as lines of text, one filename per line. The following command will create "filenames.txt":

sencha compile -classpath=src1,src2,src3 \
    meta -filenames -out filenames.txt

Each line of the file can be decorated using the -tpl option. Because of the special characters needed for this example, we use a response file to hold the template. We put this in "template.txt", like this:

<script src="{0}" type="text/javascript"></script>

Then run the following command.

sencha compile -classpath=src1,src2,src3 \
    meta -filenames -tpl @template.txt -out filenames.txt

We now have a chunk of markup that will “script-tag in” all of the files in their correct order.

For example:

<script src="ext/src/ShadowPool.js" type="text/javascript"></script>
<script src="ext/src/Shadow.js" type="text/javascript"></script>

Exporting Definitions

The compiler normally reads metadata such as classes, namespaces and dependencies by parsing source code. In situations where this is hidden, for example, when obfuscating a library, the compiler will be unaware of any defined classes or their dependencies.

This form of metadata export can be used to provide the “symbols” for such libraries so that users can still compile their application using Sencha Cmd.

sencha compile -classpath=src1,src2,src3 \
    meta -definitions -out symbols.js

The above creates a file that contains directives like this:

// @define Foo.bar.Thing
// @require Ext.panel.Panel
// @uses Ext.layout.container.HBox

These directives are recognized by the compiler and introduce the symbolic names needed for user code to compile. These symbols should be added to the obfuscated library file to ensure that the library code is concatenated in the right order.

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