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API Docs for: v3.16.0-alpha.2
Show: Inherited Protected Private Deprecated

# EmbeddedRecordsMixin Class

Defined in: `../serializer/addon/-private/embedded-records-mixin.js:12`
Module: @ember-data/serializer

## Using Embedded Records

`EmbeddedRecordsMixin` supports serializing embedded records.

To set up embedded records, include the mixin when extending a serializer, then define and configure embedded (model) relationships.

Note that embedded records will serialize with the serializer for their model instead of the serializer in which they are defined.

Below is an example of a per-type serializer (`post` type).

    import RESTSerializer, { EmbeddedRecordsMixin } from '@ember-data/serializer/rest';

    export default RESTSerializer.extend(EmbeddedRecordsMixin, {
      attrs: {
        author: { embedded: 'always' },
        comments: { serialize: 'ids' }
      }
    });

Note that this use of `{ embedded: 'always' }` is unrelated to the `{ embedded: 'always' }` that is defined as an option on `attr` as part of defining a model while working with the `ActiveModelSerializer`. Nevertheless, using `{ embedded: 'always' }` as an option to `attr` is not a valid way to set up embedded records.

The `attrs` option for a resource `{ embedded: 'always' }` is shorthand for:

    {
      serialize: 'records',
      deserialize: 'records'
    }

### Configuring Attrs

A resource's `attrs` option may be set to use `ids`, `records` or false for the `serialize` and `deserialize` settings.

The `attrs` property can be set on the `ApplicationSerializer` or a per-type serializer.

In the case where embedded JSON is expected while extracting a payload (reading) the setting is `deserialize: 'records'`, there is no need to use `ids` when extracting as that is the default behaviour without this mixin if you are using the vanilla `EmbeddedRecordsMixin`. Likewise, to embed JSON in the payload while serializing `serialize: 'records'` is the setting to use. There is an option of not embedding JSON in the serialized payload by using `serialize: 'ids'`. If you do not want the relationship sent at all, you can use `serialize: false`.

### EmbeddedRecordsMixin defaults

If you do not overwrite `attrs` for a specific relationship, the `EmbeddedRecordsMixin` will behave in the following way:

BelongsTo: `{ serialize: 'id', deserialize: 'id' }` HasMany: `{ serialize: false, deserialize: 'ids' }`

### Model Relationships

Embedded records must have a model defined to be extracted and serialized. Note that when defining any relationships on your model such as `belongsTo` and `hasMany`, you should not both specify `async: true` and also indicate through the serializer's `attrs` attribute that the related model should be embedded for deserialization. If a model is declared embedded for deserialization (`embedded: 'always'` or `deserialize: 'records'`), then do not use `async: true`.

To successfully extract and serialize embedded records the model relationships must be set up correctly. See the defining relationships section of the Defining Models guide page.

Records without an `id` property are not considered embedded records, model instances must have an `id` property to be used with Ember Data.

### Example JSON payloads, Models and Serializers

When customizing a serializer it is important to grok what the customizations are. Please read the docs for the methods this mixin provides, in case you need to modify it to fit your specific needs.

For example, review the docs for each method of this mixin:

- normalize
- serializeBelongsTo
- serializeHasMany

- Index
- Methods

## Item Index

### Methods

- _extractEmbeddedBelongsTo
- _extractEmbeddedHasMany
- _extractEmbeddedRecords
- _normalizeEmbeddedRelationship
- normalize
- removeEmbeddedForeignKey
- serializeBelongsTo
- serializeHasMany

## Methods

### `_extractEmbeddedBelongsTo`

() private

Defined in `../serializer/addon/-private/embedded-records-mixin.js:586`

### `_extractEmbeddedHasMany`

() private

Defined in `../serializer/addon/-private/embedded-records-mixin.js:557`

### `_extractEmbeddedRecords`

() private

Defined in `../serializer/addon/-private/embedded-records-mixin.js:539`

### `_normalizeEmbeddedRelationship`

() private

Defined in `../serializer/addon/-private/embedded-records-mixin.js:609`

### `normalize`

(

- `typeClass`
- `hash`
- `prop`

)
Object

Defined in `../serializer/addon/-private/embedded-records-mixin.js:104`

Normalize the record and recursively normalize/extract all the embedded records while pushing them into the store as they are encountered

A payload with an attr configured for embedded records needs to be extracted:

    {
      "post": {
        "id": "1"
        "title": "Rails is omakase",
        "comments": [{
          "id": "1",
          "body": "Rails is unagi"
        }, {
          "id": "2",
          "body": "Omakase O_o"
        }]
      }
    }

#### Parameters:

- `typeClass` Model
- `hash` Object

  to be normalized

- `prop` String

  the hash has been referenced by

#### Returns:

Object:

the normalized hash

### `removeEmbeddedForeignKey`

(

- `snapshot`
- `embeddedSnapshot`
- `relationship`
- `json`

)

Defined in `../serializer/addon/-private/embedded-records-mixin.js:462`

When serializing an embedded record, modify the property (in the `JSON` payload) that refers to the parent record (foreign key for the relationship).

Serializing a `belongsTo` relationship removes the property that refers to the parent record

Serializing a `hasMany` relationship does not remove the property that refers to the parent record.

#### Parameters:

- `snapshot` Snapshot
- `embeddedSnapshot` Snapshot
- `relationship` Object
- `json` Object

### `serializeBelongsTo`

(

- `snapshot`
- `json`
- `relationship`

)

Defined in `../serializer/addon/-private/embedded-records-mixin.js:147`

Serialize `belongsTo` relationship when it is configured as an embedded object.

This example of an author model belongs to a post model:

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

    Post = Model.extend({
      title:    attr('string'),
      body:     attr('string'),
      author:   belongsTo('author')
    });

    Author = Model.extend({
      name:     attr('string'),
      post:     belongsTo('post')
    });

Use a custom (type) serializer for the post model to configure embedded author

    import RESTSerializer, { EmbeddedRecordsMixin } from '@ember-data/serializer/rest';

    export default RESTSerializer.extend(EmbeddedRecordsMixin, {
      attrs: {
        author: { embedded: 'always' }
      }
    })

A payload with an attribute configured for embedded records can serialize the records together under the root attribute's payload:

    {
      "post": {
        "id": "1"
        "title": "Rails is omakase",
        "author": {
          "id": "2"
          "name": "dhh"
        }
      }
    }

#### Parameters:

- `snapshot` Snapshot
- `json` Object
- `relationship` Object

### `serializeHasMany`

(

- `snapshot`
- `json`
- `relationship`

)

Defined in `../serializer/addon/-private/embedded-records-mixin.js:248`

Serializes `hasMany` relationships when it is configured as embedded objects.

This example of a post model has many comments:

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

    Post = Model.extend({
      title:    attr('string'),
      body:     attr('string'),
      comments: hasMany('comment')
    });

    Comment = Model.extend({
      body:     attr('string'),
      post:     belongsTo('post')
    });

Use a custom (type) serializer for the post model to configure embedded comments

    import RESTSerializer, { EmbeddedRecordsMixin } from '@ember-data/serializer/rest';

    export default RESTSerializer.extend(EmbeddedRecordsMixin, {
      attrs: {
        comments: { embedded: 'always' }
      }
    })

A payload with an attribute configured for embedded records can serialize the records together under the root attribute's payload:

    {
      "post": {
        "id": "1"
        "title": "Rails is omakase",
        "body": "I want this for my ORM, I want that for my template language..."
        "comments": [{
          "id": "1",
          "body": "Rails is unagi"
        }, {
          "id": "2",
          "body": "Omakase O_o"
        }]
      }
    }

The attrs options object can use more specific instruction for extracting and serializing. When serializing, an option to embed `ids`, `ids-and-types` or `records` can be set. When extracting the only option is `records`.

So `{ embedded: 'always' }` is shorthand for: `{ serialize: 'records', deserialize: 'records' }`

To embed the `ids` for a related object (using a hasMany relationship):

    import RESTSerializer, { EmbeddedRecordsMixin } from '@ember-data/serializer/rest';

    export default RESTSerializer.extend(EmbeddedRecordsMixin, {
      attrs: {
        comments: { serialize: 'ids', deserialize: 'records' }
      }
    })

    {
      "post": {
        "id": "1"
        "title": "Rails is omakase",
        "body": "I want this for my ORM, I want that for my template language..."
        "comments": ["1", "2"]
      }
    }

To embed the relationship as a collection of objects with `id` and `type` keys, set `ids-and-types` for the related object.

This is particularly useful for polymorphic relationships where records don't share the same table and the `id` is not enough information.

For example having a user that has many pets:

    User = Model.extend({
      name: attr('string'),
      pets: hasMany('pet', { polymorphic: true })
    });

    Pet = Model.extend({
      name: attr('string'),
    });

    Cat = Pet.extend({
      // ...
    });

    Parrot = Pet.extend({
      // ...
    });

    import RESTSerializer, { EmbeddedRecordsMixin } from '@ember-data/serializer/rest';

    export default RESTSerializer.extend(EmbeddedRecordsMixin, {
      attrs: {
        pets: { serialize: 'ids-and-types', deserialize: 'records' }
      }
    });

    {
      "user": {
        "id": "1"
        "name": "Bertin Osborne",
        "pets": [
          { "id": "1", "type": "Cat" },
          { "id": "1", "type": "Parrot"}
        ]
      }
    }

#### Parameters:

- `snapshot` Snapshot
- `json` Object
- `relationship` Object