DS Namespace addon/-private/core.js:8

DS.attr defines an attribute on a DS.Model. By default, attributes are passed through as-is, however you can specify an optional type to have the value automatically transformed. Ember Data ships with four basic transform types: string, number, boolean and date. You can define your own transforms by subclassing DS.Transform.

Note that you cannot use attr to define an attribute of id.

DS.attr takes an optional hash as a second parameter, currently supported options are:

• defaultValue: Pass a string or a function to be called to set the attribute to a default value if none is supplied.

Example

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import DS from 'ember-data';

export default DS.Model.extend({
  username: DS.attr('string'),
  email: DS.attr('string'),
  verified: DS.attr('boolean', { defaultValue: false })
});

Default value can also be a function. This is useful it you want to return a new object for each attribute.

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import DS from 'ember-data';

export default DS.Model.extend({
  username: attr('string'),
  email: attr('string'),
  settings: attr({defaultValue: function() {
    return {};
  }})
});

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

DS.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.
• inverse: A string used to identify the inverse property on a related model in a One-To-Many relationship. See Explicit Inverses

One-To-One

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

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import DS from 'ember-data';

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

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import DS from 'ember-data';

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

One-To-Many

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

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import DS from 'ember-data';

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

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import DS from 'ember-data';

export default DS.Model.extend({
  post: DS.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 DS from 'ember-data';

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

will lookup for a Post type.

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

DS.hasMany 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.
• inverse: A string used to identify the inverse property on a related model.

One-To-Many

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

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import DS from 'ember-data';

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

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import DS from 'ember-data';

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

Many-To-Many

To declare a many-to-many relationship between two models, use DS.hasMany:

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import DS from 'ember-data';

export default DS.Model.extend({
  tags: DS.hasMany('tag')
});

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import DS from 'ember-data';

export default DS.Model.extend({
  posts: DS.hasMany('post')
});

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

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import DS from 'ember-data';

export default DS.Model.extend({
  tags: DS.hasMany()
});

will lookup for a Tag type.

Explicit Inverses

Ember Data will do its best to discover which relationships map to one another. In the one-to-many code above, for example, Ember Data can figure out that changing the comments relationship should update the post relationship on the inverse because post is the only relationship to that model.

However, sometimes you may have multiple belongsTo/hasManys for the same type. You can specify which property on the related model is the inverse using DS.hasMany's inverse option:

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import DS from 'ember-data';

export default DS.Model.extend({
  onePost: DS.belongsTo('post'),
  twoPost: DS.belongsTo('post'),
  redPost: DS.belongsTo('post'),
  bluePost: DS.belongsTo('post')
});

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import DS from 'ember-data';

export default DS.Model.extend({
  comments: DS.hasMany('comment', {
    inverse: 'redPost'
  })
});

You can also specify an inverse on a belongsTo, which works how you'd expect.