Package @ember-data/canary-features

Canary Features

EmberData allows users to test features that are implemented but not yet available even in canary.

Typically these features represent work that might introduce a new concept, new API, change an API, or risk an unintended change in behavior to consuming applications.

Such features have their implementations guarded by a "feature flag", and the flag is only activated once the core-data team is prepared to ship the work in a canary release.

Installing Canary

To test a feature you MUST be using a canary build. Canary builds are published to npm and can be installed using a precise tag (such as [email protected]) or by installing the latest dist-tag published to the canary channel.

Using npm to install the latest canary

npm install --save-dev ember-data@canary

Using yarn to install the latest canary

yarn add ember-data@canary

Activating a Canary Feature

Once you have installed canary, feature-flags can be activated at build-time by an environment variable or at runtime using window.EmberDataENV.

The "off" branch of feature-flagged code is always stripped from production builds, so you MUST use the build-time environment variable to activate a flag if testing production.

The list of available feature-flags is located here

Runtime Configuration

To configure feature-flags at runtime you will want to configure window.EmberDataENV = {} appropriately. You should add this global property in your app prior to your application booting. At the top of your app.js file is a convenient location, as is within index.html as a script running prior to loading any other scripts.

Example activating a single feature flags

window.EmberDataENV = {
  FEATURES: {
    RECORD_DATA_ERRORS: true,
  }
}

Example activating multiple feature flags

window.EmberDataENV = {
  FEATURES: {
    RECORD_DATA_ERRORS: true,
    RECORD_DATA_STATE: true,
  }
}

Example activating all feature flags

window.EmberDataENV = {
  ENABLE_OPTIONAL_FEATURES: true
}

Build Time Configuration

Example activating a single feature flags

EMBER_DATA_FEATURE_OVERRIDE=REQUEST_SERVICE ember build

Example activating multiple feature flags

EMBER_DATA_FEATURE_OVERRIDE=REQUEST_SERVICE,CUSTOM_MODEL_CLASS ember build

Example activating all feature flags

EMBER_DATA_FEATURE_OVERRIDE=ENABLE_ALL_OPTIONAL ember build

Preparing an Addon to use a Canary Feature

For most addons and most features simple version detection should be enough. Using the provided version compatibility helpers from ember-compatibility-helpers the following can be done:

if (gte('@ember-data/store', '3.12.0')) {

} else {

}

For addons needing more advanced detection babel-plugin-debug-macros can be leveraged to provide code-stripping based on feature presence. For example in your addon's index.js:

function debugMacros(features) {
  let plugins = [
    [
      require.resolve('babel-plugin-debug-macros'),
      {
        flags: [
          {
            source: '<addon-name>/feature-flags',
            flags: features,
          },
        ],
      },
      '<addon-name>/canary-features-stripping',
    ],
  ];

  return plugins;
}

module.exports = {
  name: '<addon-name>',

  init() {
    this._super.init.apply(this, arguments);

    let features;
    try {
      features = this.project.require('@ember-data/private-build-infra/src/features')();
    } catch (e) {
      features = { CUSTOM_MODEL_CLASS: false };
    }

    this.options = this.options || {};
    this.options.babel = this.options.babel || {};
    // this ensures that the same `@ember-data/canary-features` processing that the various
    // ember-data addons do is done for this addon
    this.options.babel.plugins = [...debugMacros(features)];
  }
}