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ember-concurrency-decorators

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Readme

ember-concurrency-decorators

This Ember addon lets you use the decorator syntax for declaring/configuring ember-concurrency tasks.

Installation

You'll need at least ember-cli@2.13+ and ember-cli-babel@6+. Then install as any other addon:

ember install ember-concurrency-decorators

If you are not using TypeScript, in order for ember-cli-babel to understand the @decorator syntax, you at least also need to install @ember-decorators/babel-transforms. Instead of that you can also install the ember-decorators meta package:

ember install ember-decorators
# or
ember install @ember-decorators/babel-transforms

You need at least @ember-decorators/babel-transforms@^3.1.0. If you are stuck on v2.1.2, use ember-concurrency-decorators@0.3.0.

Usage

Available decorators

@task: turns a generator method into a task
- @restartableTask
- @dropTask
- @keepLatestTask
- @enqueueTask
@taskGroup: creates a task group from a property
- @restartableTaskGroup
- @dropTaskGroup
- @keepLatestTaskGroup
- @enqueueTaskGroup
@lastValue: alias a property to the result of a task with an optional default value

`@task`

import Component from '@ember/component';
import { task } from 'ember-concurrency-decorators';

export default class ExampleComponent extends Component {
  @task
  *doStuff() {
    // ...
  }

  // and then elsewhere
  executeTheTask() {
    // `doStuff` is still a `Task` object that can be `.perform()`ed
    this.doStuff.perform();
    console.log(this.doStuff.isRunning);
  }
}

You can also pass further options to the task decorator:

@task({
  maxConcurrency: 3,
  restartable: true
})
*doStuff() {
  // ...
}

For your convenience, there are extra decorators for all concurrency modifiers:

Shorthand	Equivalent
`@restartableTask`	`@task({ restartable: true })`
`@dropTask`	`@task({ drop: true })`
`@keepLatestTask`	`@task({ keepLatest: true })`
`@enqueueTask`	`@task({ enqueue: true })`

You can still pass further options to these decorators, like:

@restartableTask({ maxConcurrency: 3 })
*doStuff() {
  // ...
}

Encapsulated Tasks

Encapsulated Tasks behave just like regular tasks, but with one crucial difference: the value of this within the task function points to the currently running TaskInstance, rather than the host object that the task lives on (e.g. a Component, Controller, etc). This allows for some nice patterns where all of the state produced/mutated by a task can be contained (encapsulated) within the Task itself, rather than having to live on the host object.

import Component from '@ember/component';
import { task } from 'ember-concurrency-decorators';

export default class ExampleComponent extends Component {
  @task
  doStuff = {
    privateState: 123,
    *perform() {
      // ...
    }
  };

  // and then elsewhere
  executeTheTask() {
    // `doStuff` is still a `Task` object that can be `.perform()`ed
    this.doStuff.perform();
    console.log(this.doStuff.isRunning);
  }
}

Encapulated Tasks do not work with ember-cli-typescript@1. See the TypeScript section for more details.

`@taskGroup`

import Component from '@ember/component';
import { task, taskGroup } from 'ember-concurrency-decorators';

export default class ExampleComponent extends Component {
  @taskGroup
  someTaskGroup;

  @task({ group: 'someTaskGroup' })
  *doStuff() {
    // ...
  }

  @task({ group: 'someTaskGroup' })
  *doOtherStuff() {
    // ...
  }

  // and then elsewhere
  executeTheTask() {
    // `doStuff` is still a `Task `object that can be `.perform()`ed
    this.doStuff.perform();

    // `someTaskGroup` is still a `TaskGroup` object
    console.log(this.someTaskGroup.isRunning);
  }
}

You can also pass further options to the task group decorator:

@taskGroup({
  maxConcurrency: 3,
  drop: true
}) someTaskGroup;

As for @task, there are extra decorators for all concurrency modifiers:

Shorthand	Equivalent
`@restartableTaskGroup`	`@taskGroup({ restartable: true })`
`@dropTaskGroup`	`@taskGroup({ drop: true })`
`@keepLatestTaskGroup`	`@taskGroup({ keepLatest: true })`
`@enqueueTaskGroup`	`@taskGroup({ enqueue: true })`

You can still pass further options to these decorators, like:

@dropTaskGroup({ maxConcurrency: 3 }) someTaskGroup;

`@lastValue`

This decorator allows you to alias a property to the result of a task. You can also provide a default value to use before the task has completed.

import Component from '@ember/component';
import { task } from 'ember-concurrency-decorators';
import { lastValue } from 'ember-concurrency-decorators';

export default class ExampleComponent extends Component {
  @task
  *someTask() {
    // ...
  }

  @lastValue('someTask')
  someTaskValue;

  @lastValue('someTask')
  someTaskValueWithDefault = 'A default value';
}

Support

JavaScript

While ember-cli-babel@6 is still supported and tested, we highly recommend that you update to ember-cli-babel@7, if you have not already.

If you are using ember-cli-babel@6, you'll need to use slightly different syntax:

import Component from '@ember/component';
import { task } from 'ember-concurrency-decorators';

export default class ExampleComponent extends Component {
  @task
  doStuff = function*() {
    // You need to use a function assignment here, instead of the method shorthand.
  };
}

TypeScript

If you are using TypeScript, we highly recommend that you use at least ember-cli-typescript@^2.0.0-beta.3. Otherwise encapsulated tasks will not work.

License

This project is licensed under the MIT License.