Function

belongsTo (modelName, options) Ember.computed public

Defined in ../model/addon/-private/belongs-to.js:13

modelName

String

(optional) type of the relationship

options

Object

(optional) a hash of options

returns

Ember.computed

relationship

belongsTo is used to define One-To-One and One-To-Many relationships on a Model.

belongsTo takes an optional hash as a second parameter, currently supported options are:

• async: A boolean value used to explicitly declare this to be an async relationship. The default is true.
• inverse: A string used to identify the inverse property on a related model in a One-To-Many relationship. See Explicit Inverses
• polymorphic A boolean value to mark the relationship as polymorphic

One-To-One

To declare a one-to-one relationship between two models, use belongsTo:

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import Model, { belongsTo } from '@ember-data/model';

export default Model.extend({
  profile: belongsTo('profile')
});

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import Model, { belongsTo } from '@ember-data/model';

export default Model.extend({
  user: belongsTo('user')
});

One-To-Many

To declare a one-to-many relationship between two models, use belongsTo in combination with hasMany, like this:

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import Model, { hasMany } from '@ember-data/model';

export default Model.extend({
  comments: hasMany('comment')
});

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import Model, { belongsTo } from '@ember-data/model';

export default Model.extend({
  post: belongsTo('post')
});

You can avoid passing a string as the first parameter. In that case Ember Data will infer the type from the key name.

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import Model, { belongsTo } from '@ember-data/model';

export default Model.extend({
  post: belongsTo()
});

will lookup for a Post type.

Sync relationships

Ember Data resolves sync relationships with the related resources available in its local store, hence it is expected these resources to be loaded before or along-side the primary resource.

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import Model, { belongsTo } from '@ember-data/model';

export default Model.extend({
  post: belongsTo('post', {
    async: false
  })
});

In contrast to async relationship, accessing a sync relationship will always return the record (Model instance) for the existing local resource, or null. But it will error on access when a related resource is known to exist and it has not been loaded.

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let post = comment.get('post');