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Install front end dependencies

The front end stylesheets are written using LESS. This depends on node being installed on the system.

Instructions for installing node can be found on the project website.

On ubuntu node can be installed using the following commands:

$ sudo apt-get install nodejs
$ sudo apt-get install npm    # node package manager

LESS can then be installed via the node package manager which is bundled with node (or installed with apt). cd into the pyenv/src/ckan and run:

$ npm install less

A watcher script can then be used to compile the CSS whenever the LESS changes:

$ ./bin/less

This will generate a main.debug.css file. To build the production CSS to commit into the repository run:

$ ./bin/less --production

This will generate the main.css file that should be committed for use in packaged versions of CKAN. (This command will actually start a watch script so you'll have to exit it with ctrl-c to actually commit the file.)

(If someone could move this into a paster script that would be great)

File Structure

All front-end files to be served via a web server are located in the public directory (in the case of the new CKAN base theme it's public/base).

css/
  main.css
less/
  main.less
  ckan.less
javascript/
  main.js
  utils.js
  components/
vendor/
  jquery.js
  jquery.plugin.js
  underscore.js
  bootstrap.css
test/
  index.html
  spec/
    main.spec.js
    utils.spec.js
  vendor/
    mocha.js
    mocha.css
    chai.js

All files and directories should be lowercase with hyphens used to separate words.

css

Should contain any site specific CSS files including compiled production builds generated by LESS.

less

Should contain all the less files for the site. Additional vendor styles should be added to the vendor directory and included in main.less.

javascript

Should contain all website files. These can be structured appropriately. It is recommended that main.js be used as the bootstrap filename that sets up the page.

vendor

Should contain all external dependencies. These should not contain version numbers in the filename. This information should be available in the header comment of the file. Library plugins should be prefixed with the library name. If a dependency has many files (such as bootstrap) then the entire directory should be included as distributed by the maintainer.

test

Contains the test runner index.html. vendor contains all test dependencies and libraries. spec contains the actual test files. Each test file should be the filename with .spec appended.

Stylesheets

Because all the stylesheets are using LESS we need to compile them before beginning development. In production CKAN will look for the main.css file which is included in the repository. In development CKAN looks for the file main.debug.css which you will need to generate by running:

$ ./bin/less

This will watch for changes to all of the less files and automatically rebuild the CSS for you. To quit the script press ctrl-c.

There are many LESS scripts which attempt to group the styles in useful groups.

The main two are:

  • main.less: This contains all the styles for the website including dependancies and local styles. The only files that are excluded here are those that are conditionally loaded such as IE only CSS and large external apps (like recline) that only appear on a single page.
  • ckan.less: This includes all the local ckan stylesheets.

There is a very basic pattern primer available at:

http://localhost:5000/test/primer/

This should contain common components and slowly be expanded to provide documentation on the CKAN markup and styles. But for the moment it serves as useful unit tests for the CSS.

JavaScript

The core of the CKAN JavaScript is split up into three areas.

  • Core (such as i18n, pub/sub and API clients)
  • Modules (small HTML components or widgets)
  • jQuery Plugins (very small reusable components)

Core

Everything in the CKAN application lives on the ckan namespace. Currently there are four main components that make up the core.

Modules

Modules are the core of the CKAN website, every component that is interactive on the page should be a module. These are then initialized by including a data-module attribute on an element on the page.

The idea is to create small isolated components that can easily be tested. They should ideally not use any global objects, all functionality should be provided to them via a "sandbox" object.

There is a global factory that can be used to create new modules.

ckan.module('my-module', {
  initialize: function () {
    // Called when a module is created.
  },
  teardown: function () {
    // Called before a module is removed from the page.
  }
});

jQuery and Localisation methods are available via this.sandbox.jQuery and this.sandbox.translate() respectively. To save typing these two common objects we can take advantage of JavaScript closures and use an alternative module syntax that accepts a factory function.

ckan.module('my-module', function (jQuery, translate) {
  return {
    initialize: function () {
      // Called when a module is created.
      // jQuery and translate are available here.
    },
    teardown: function () {
      // Called before a module is removed from the page.
    }
  }
});

Pub/Sub

There is a simple pub/sub module included under ckan.pubsub it's methods are available to modules via this.sandbox.publish/subscribe/unsubscribe. This can be used to publish messages between modules.

Client

Ideally no module should use jQuery.ajax() to make XHR requests to the CKAN API, all functionality should be provided via the client object.

ckan.module('my-module', {
  initialize: function () {
    this.sandbox.client.getCompletions(this.options.completionsUrl);
  }
});

i18n/Jed

Jed is a Gettext implementation in JavaScript. It is used throughout the application to create translatable strings. An instance of Jed is available on the ckan.i18n object.

Modules get access to the translate() function via both the initial factory function and the this.sandbox.translate() object.

ckan.module('my-module', function (jQuery, translate) {
  return {/* my module */};
});

ckan.module('my-module', {
  initialize: function () {
    this.sandbox.translate('my string');
  }
});

String interpolation can be provided using the sprintf formatting. We always use the named arguments to keep in line with the Python translations. And we name the translate function passed into ckan.module() _.

ckan.module('my-module', function (jQuery, _) {
  return {
    initialize: function () {
      // Keyword arguments
      _('Hello %(name)s').fetch({name: 'Bill'}); // Hello Bill

      // Multiple.
      _("I like your %(color)s %(fruit)s.").fetch({color: 'red', fruit: 'apple');

      // Plurals.
      _("I have %(num)d apple.")
        .ifPlural(2, "I have %(num)d apples.")
        .fetch({num: 2, fruit: 'apple');
    }
  };
});

Modules

Life Cycle

CKAN modules are intialised on document ready. The ckan.module.initialize() will look for all elements on the page with a data-module attribute and attempt to create an instance.

<select name="format" data-module="autocomplete"></select>

The module will be created with the element, an options object extracted from data-module-* attributes and a new sandbox instance.

Once created the modules initialize() method will be called allowing the module to set themselves up.

Modules should also provide a teardown() method this isn't used at the moment except in the unit tests to restore state but may become useful in the future.

Talking to each other

Modules should use the publish/subscribe methods to talk to each other and allow different areas of the UI to update where relevant.

ckan.module('language-picker', {
  initialize: function () {
    var sandbox = this.sandbox;
    this.el.on('change', function () {
      sandbox.publish('change:lang', this.selected);
    });
  }
});

ckan.module('language-notifier', {
  initialize: function () {
    this.sandbox.subscribe('change:lang', function (lang) {
      alert('language is now ' + lang);
    });
  }
});

Internationalisation

All strings within modules should be internationalised. Strings can be set in the options.i18n object and there is a .i18n() helper for retrieving them.

ckan.module('language-picker', function (jQuery, _) {
  return {
    options: {
      i18n: {
        hello: _('Hello')
      }
    },
    initialize: function () {
      this.i18n('hello'); // "Hello"
    }
  }
});

String interpolation can be provided by passing extra arguments.

ckan.module('language-picker', function (jQuery, _) {
  return {
    options: {
      i18n: {
        hello: _('Hello %(name)s')
      }
    },
    initialize: function () {
      var name = 'Dave';
      this.i18n('hello', {name: name}); // "Hello Dave"
    }
  }
});

Plural versions can also be provided using a function and the chained Jed API.

ckan.module('language-picker', function (jQuery, _) {
  return {
    options: {
      i18n: {
        apples: function (params) {
          var n = params.num;
          return _('I have %(num)d apple').isPlural(n, 'I have %(num)d apples');
        }
      }
    },
    initialize: function () {
      var total = 1;
      this.i18n('apples', {num: total}); // "I have 1 apple"
      this.i18n('apples', {num: 3});     // "I have 3 apples"
    }
  }
});

jQuery Plug-ins

Any functionality that is not directly related to ckan should be packaged up in a jQuery plug-in if possible. This keeps the modules containing only ckan specific code and allows plug-ins to be reused on other sites.

Examples of these are jQuery.fn.slug(), jQuery.fn.slugPreview() and jQuery.proxyAll().

Unit Tests

There is currently a test suite available at:

http://localhost:5000/base/test/index.html

Every core component, module and plugin should have a set of unit tests. Tests can be filtered using the grep={regexp} query string parameter.

http://localhost:5000/base/test/index.html?grep=^jQuery

The libraries used for the tests are as follows.

  • Mocha: A test runner using a BDD style syntax.
  • Chai: An assertion library (we use the assert style).
  • Sinon: A stubbing library, can stub objects, timers and ajax requests.