AngularJS Topic Guide

Note

This guide is a work in progress. It has been uploaded to encourage faster reviewing and code development in Angular, and to help the community standardize on a set of guidelines. There are notes inline on sections that are likely to change soon, and the docs will be updated promptly after any changes.

Getting Started

The tooling for AngularJS testing and code linting relies on npm, the node package manager, and thus relies on Node.js. While it is not a prerequisite to developing with Horizon, it is advisable to install Node.js, either through downloading or via a package manager.

Once you have npm available on your system, run npm install from the horizon root directory.

Code Style

We currently use the Angular Style Guide by John Papa as reference material. When reviewing AngularJS code, it is helpful to link directly to the style guide to reinforce a point, e.g. https://github.com/johnpapa/angular-styleguide#style-y024

ESLint

ESLint is a tool for identifying and reporting on patterns in your JS code, and is part of the automated tests run by Jenkins. You can run ESLint from the horizon root directory with npm run lint, or alternatively on a specific directory or file with eslint file.js.

Horizon includes a .eslintrc in its root directory, that is used by the local tests. An explanation of the options, and details of others you may want to use, can be found in the ESLint user guide.

Application Structure

OpenStack Dashboard is an example of a Horizon-based Angular application. Other applications built on the Horizon framework can follow a similar structure. It is composed of two key Angular modules:

app.module.js - The root of the application. Defines the modules required by

the application, and includes modules from its pluggable dashboards.

framework.module.js - Reusable Horizon components. It is one of the

application dependencies.

File Structure

Horizon has three kinds of angular code:

1. Specific to one dashboard in the OpenStack Dashboard application
2. Specific to the OpenStack Dashboard application, but reusable by multiple dashboards
3. Reusable by any application based on the Horizon framework

When adding code to horizon, consider whether it is dashboard-specific or should be broken out as a reusable utility or widget.

Code specific to one dashboard

Code that isn’t shared beyond a single dashboard is placed in openstack_dashboard/dashboards/mydashboard/static. Entire dashboards may be enabled or disabled using Horizon’s plugin mechanism. Therefore no dashboards other than mydashboard can safely use this code.

The openstack_dashboard/dashboards/static directory structure determines how the code is deployed and matches the module structure. For example:

openstack_dashboard/dashboards/identity/static/dashboard/identity/
├── identity.module.js
├── identity.module.spec.js
└── identity.scss

Because the code is in openstack_dashboard/dashboards/identity we know it is specific to just the identity dashboard and not used by any others.

Code shared by multiple dashboards

Views or utilities needed by multiple dashboards are placed in openstack_dashboard/static/app. For example:

openstack_dashboard/static/app/core/cloud-services/
├── cloud-services.js
└── cloud-services.spec.js

The cloud-services module is used by panels in multiple dashboards. It cannot be placed within openstack_dashboard/dashboards/mydashboard because disabling that one dashboard would break others. Therefore, it is included as part of the application core module. Code in app/ is guaranteed to always be present, even if all other dashboards are disabled.

Reusable components

Finally, components that are easily reused by any application are placed in horizon/static/framework/. These do not contain URLs or business logic that is specific to any application (even the OpenStack Dashboard application).

The modal directive horizon/static/framework/widgets/modal/ is a good example of a reusable component.

One folder per component

Each component should have its own folder, with the code broken up into one JS component per file. (See Single Responsibility in the style guide). Each folder may include styling (.scss), as well as templates(.html) and tests (.spec.js). You may also include examples, by appending .example.

For larger components, such as workflows with multiple steps, consider breaking the code down further. For example, the Launch Instance workflow, has one directory per step. See openstack_dashboard/dashboards/project/static/dashboard/project/workflow/launch-instance/

SCSS files

The top-level SCSS file in openstack_dashboard/static/app/app.scss. It includes any styling that is part of the application core and may be reused by multiple dashboards. SCSS files that are specific to a particular dashboard are linked to the application by adding them in that dashboard’s enabled file. For example, _1000_project.py is the enabled file for the Project dashboard and includes:

ADD_SCSS_FILES = [
    'dashboard/project/project.scss',
]

Styling files are hierarchical, and include any direct child SCSS files. For example, project.scss includes the workflow SCSS file, which in turn includes any launch instance styling:

@import "workflow/workflow";

This allows the application to easily include all needed styling, simply by including a dashboards top-level SCSS file.

Module Structure

Horizon Angular modules use names that map to the source code directory structure. This provides namespace isolation for modules and services, which makes dependency injection clearer. It also reduces code conflicts where two different modules define a module, service or constant of the same name. For example:

openstack_dashboard/dashboards/identity/static/dashboard/identity/
└── identity.module.js

The preferred Angular module name in this example is horizon.dashboard.identity. The horizon part of the module name maps to the static directory and indicates this is a horizon based application. dashboard.identity maps to folders that are created within static. This allows a direct mapping between the angular module name of horizon.dashboard.identity and the source code directory of static\dashboard\identity.

Services and constants within these modules should all start with their module name to avoid dependency injection collisions. For example:

$provide.constant('horizon.dashboard.identity.basePath', path);

Directives do not require the module name but are encouraged to begin with the hz prefix. For example:

.directive('hzMagicSearchBar', hzMagicSearchBar);

Finally, each module lists its child modules as a dependency. This allows the root module to be included by an application, which will automatically define all child modules. For example:

.module('horizon.framework', [
  'horizon.framework.conf',
  'horizon.framework.util',
  'horizon.framework.widgets'
])

horizon.framework declares a dependency on horizon.framework.widgets, which declares dependencies on each individual widget. This allows the application to access any widget, simply by depending on the top-level horizon.framework module.

Testing

1. Open <dev_server_ip:port>/jasmine in a browser. The development server can be run with``./run_tests.sh –runserver`` from the horizon root directory.
2. npm run test from the horizon root directory.

The code linting job can be run with npm run lint.

For more detailed information, see JavaScript Testing.

Translation (Internationalization and Localization)

Translations are handled in Transifex, as with Django. They are merged daily with the horizon upstream codebase. See Translations in the OpenStack wiki to learn more about this process.

To translate text in HTML files, you may use the translate directive or filter. The directive be used as an element, or an attribute:

// Translate singular, as element
<translate>Lorem ipsum</translate>

// Translate singular, as attribute
<h1 translate>Lorem ipsum</h1>

// Translate plural (attribute only)
<div translate translate-n="count" translate-plural="apples">apple</div>

// Filter singular
<input type="text" placeholder="{$ 'Username' | translate $}" />

// Comments for translators, to add context
<h1 translate-comment="Verb" translate>File</h1>

Note

The filter does not support plural strings.

To translate text in JS files, such as Angular controllers, use either gettext (singular) or ngettext (plural):

gettext('apple');
ngettext('apple', 'apples', count);

The Translatability section contains information about the pseudo translation tool, and how to make sure your translations are working locally.

Horizon uses the angular-gettext library to provide directives and filters for extracting translatable text.

Creating your own panel

Note

This section will be extended as standard practices are adopted upstream. Currently, it may be useful to use this patch and its dependants as an example.

Note

Currently, Angular module names must still be manually declared with ADD_ANGULAR_MODULES, even when using automatic file discovery.

This section serves as a basic introduction to writing your own panel for horizon, using AngularJS. A panel may be included with the plugin system, or it may be part of the upstream horizon project.

Upstream

JavaScript files can be discovered automatically, handled manually, or a mix of the two. Where possible, use the automated mechanism. To use the automatic functionality, add:

AUTO_DISCOVER_STATIC_FILES = True

to your enabled file (enabled/<plugin_name>.py). To make this possible, you need to follow some structural conventions:

• Static files should be put in a static/ folder, which should be found directly under the folder for the dashboard/panel/panel groups Python package.
• JS code that defines an Angular module should be in a file with extension of .module.js.
• JS code for testing should be named with extension of .mock.js and of .spec.js.
• Angular templates should have extension of .html.

You can read more about the functionality in the AUTO_DISCOVER_STATIC_FILES section of the settings documentation.

To manually add files, add the following arrays and file paths to the enabled file:

ADD_JS_FILES = [
  ...
  'path-to/my-angular-code.js',
  ...
]

ADD_JS_SPEC_FILES = [
  ...
  'path-to/my-angular-code.spec.js',
  ...
]

ADD_ANGULAR_MODULES = [
  ...
  'angular.module',
  ...
]

Plugins

Add a new panel/ panel group/ dashboard (See Tutorial: Building a Dashboard using Horizon). JavaScript file inclusion is the same as the Upstream process.

To include external stylesheets, you must ensure that ADD_SCSS_FILES is defined in your enabled file, and add the relevant filepath, as below:

ADD_SCSS_FILES = [
  ...
  'path-to/my-styles.scss',
  ...
]

Note

We highly recommend using a single SCSS file for your plugin. SCSS supports nesting with @import, so if you have multiple files (i.e. per panel styling) it is best to import them all into one, and include that single file. You can read more in the SASS documentation.