DS.JSONSerializer Class
Ember Data 2.0 Serializer:
In Ember Data a Serializer is used to serialize and deserialize records when they are transferred in and out of an external source. This process involves normalizing property names, transforming attribute values and serializing relationships.
By default, Ember Data uses and recommends the JSONAPISerializer
.
JSONSerializer
is useful for simpler or legacy backends that may
not support the http://jsonapi.org/ spec.
For example, given the following User
model and JSON payload:
import DS from 'ember-data';
export default DS.Model.extend({
friends: DS.hasMany('user'),
house: DS.belongsTo('location'),
name: DS.attr('string')
});
{
id: 1,
name: 'Sebastian',
friends: [3, 4],
links: {
house: '/houses/lefkada'
}
}
JSONSerializer
will normalize the JSON payload to the JSON API format that the
Ember Data store expects.
You can customize how JSONSerializer processes its payload by passing options in
the attrs
hash or by subclassing the JSONSerializer
and overriding hooks:
- To customize how a single record is normalized, use the
normalize
hook. - To customize how
JSONSerializer
normalizes the whole server response, use thenormalizeResponse
hook. - To customize how
JSONSerializer
normalizes a specific response from the server, use one of the many specificnormalizeResponse
hooks. - To customize how
JSONSerializer
normalizes your id, attributes or relationships, use theextractId
,extractAttributes
andextractRelationships
hooks.
The JSONSerializer
normalization process follows these steps:
normalizeResponse
- entry method to the serializer.normalizeCreateRecordResponse
- anormalizeResponse
for a specific operation is called.normalizeSingleResponse
|normalizeArrayResponse
- for methods likecreateRecord
we expect a single record back, while for methods likefindAll
we expect multiple records back.normalize
-normalizeArray
iterates and callsnormalize
for each of its records whilenormalizeSingle
calls it once. This is the method you most likely want to subclass.extractId
|extractAttributes
|extractRelationships
-normalize
delegates to these methods to turn the record payload into the JSON API format.
Item Index
Methods
- _canSerialize
- _getMappedKey
- _mustSerialize
- _normalizeResponse
- applyTransforms
- extractAttributes
- extractErrors
- extractId
- extractMeta
- extractPolymorphicRelationship
- extractRelationship
- extractRelationships
- keyForAttribute
- keyForLink
- keyForRelationship
- modelNameFromPayloadKey
- normalize
- normalizeArrayResponse
- normalizeCreateRecordResponse
- normalizeDeleteRecordResponse
- normalizeFindAllResponse
- normalizeFindBelongsToResponse
- normalizeFindHasManyResponse
- normalizeFindManyResponse
- normalizeFindRecordResponse
- normalizeQueryRecordResponse
- normalizeQueryResponse
- normalizeRelationships
- normalizeResponse
- normalizeSaveResponse
- normalizeSingleResponse
- normalizeUpdateRecordResponse
- normalizeUsingDeclaredMapping
- serialize
- serializeAttribute
- serializeBelongsTo
- serializeHasMany
- serializeIntoHash
- serializePolymorphicType
- shouldSerializeHasMany
- transformFor
Properties
Methods
_canSerialize
-
key
Check attrs.key.serialize property to inform if the key
can be serialized
Parameters:
-
key
String
Returns:
true if the key can be serialized
_getMappedKey
-
key
Looks up the property key that was set by the custom attr
mapping
passed to the serializer.
Parameters:
-
key
String
Returns:
key
_mustSerialize
-
key
When attrs.key.serialize is set to true then it takes priority over the other checks and the related attribute/relationship will be serialized
Parameters:
-
key
String
Returns:
true if the key must be serialized
_normalizeResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
-
isSingle
Parameters:
Returns:
JSON-API Document
applyTransforms
-
typeClass
-
data
Given a subclass of DS.Model
and a JSON object this method will
iterate through each attribute of the DS.Model
and invoke the
DS.Transform#deserialize
method on the matching property of the
JSON object. This method is typically called after the
serializer's normalize
method.
Parameters:
-
typeClass
DS.Model -
data
ObjectThe data to transform
Returns:
data The transformed data object
extractAttributes
-
modelClass
-
resourceHash
Returns the resource's attributes formatted as a JSON-API "attributes object".
http://jsonapi.org/format/#document-resource-object-attributes
Parameters:
-
modelClass
Object -
resourceHash
Object
Returns:
extractErrors
-
store
-
typeClass
-
payload
-
id
extractErrors
is used to extract model errors when a call
to DS.Model#save
fails with an InvalidError
. By default
Ember Data expects error information to be located on the errors
property of the payload object.
This serializer expects this errors
object to be an Array similar
to the following, compliant with the https://jsonapi.org/format/#errors specification:
{
"errors": [
{
"detail": "This username is already taken!",
"source": {
"pointer": "data/attributes/username"
}
}, {
"detail": "Doesn't look like a valid email.",
"source": {
"pointer": "data/attributes/email"
}
}
]
}
The key detail
provides a textual description of the problem.
Alternatively, the key title
can be used for the same purpose.
The nested keys source.pointer
detail which specific element
of the request data was invalid.
Note that JSON-API also allows for object-level errors to be placed
in an object with pointer data
, signifying that the problem
cannot be traced to a specific attribute:
{
"errors": [
{
"detail": "Some generic non property error message",
"source": {
"pointer": "data"
}
}
]
}
When turn into a DS.Errors
object, you can read these errors
through the property base
:
{{#each model.errors.base as |error|}}
<div class="error">
{{error.message}}
</div>
{{/each}}
Example of alternative implementation, overriding the default behavior to deal with a different format of errors:
import DS from 'ember-data';
export default DS.JSONSerializer.extend({
extractErrors(store, typeClass, payload, id) {
if (payload && typeof payload === 'object' && payload._problems) {
payload = payload._problems;
this.normalizeErrors(typeClass, payload);
}
return payload;
}
});
Returns:
json The deserialized errors
extractId
-
modelClass
-
resourceHash
Returns the resource's ID.
Parameters:
-
modelClass
Object -
resourceHash
Object
Returns:
extractMeta
-
store
-
modelClass
-
payload
extractMeta
is used to deserialize any meta information in the
adapter payload. By default Ember Data expects meta information to
be located on the meta
property of the payload object.
Example
import DS from 'ember-data';
export default DS.JSONSerializer.extend({
extractMeta(store, typeClass, payload) {
if (payload && payload.hasOwnProperty('_pagination')) {
let meta = payload._pagination;
delete payload._pagination;
return meta;
}
}
});
extractPolymorphicRelationship
-
relationshipModelName
-
relationshipHash
-
relationshipOptions
Returns a polymorphic relationship formatted as a JSON-API "relationship object".
http://jsonapi.org/format/#document-resource-object-relationships
relationshipOptions
is a hash which contains more information about the
polymorphic relationship which should be extracted:
resourceHash
complete hash of the resource the relationship should be extracted fromrelationshipKey
key under which the value for the relationship is extracted from the resourceHashrelationshipMeta
meta information about the relationship
Parameters:
-
relationshipModelName
Object -
relationshipHash
Object -
relationshipOptions
Object
Returns:
extractRelationship
-
relationshipModelName
-
relationshipHash
Returns a relationship formatted as a JSON-API "relationship object".
http://jsonapi.org/format/#document-resource-object-relationships
Parameters:
-
relationshipModelName
Object -
relationshipHash
Object
Returns:
extractRelationships
-
modelClass
-
resourceHash
Returns the resource's relationships formatted as a JSON-API "relationships object".
http://jsonapi.org/format/#document-resource-object-relationships
Parameters:
-
modelClass
Object -
resourceHash
Object
Returns:
keyForAttribute
-
key
-
method
keyForAttribute
can be used to define rules for how to convert an
attribute name in your model to a key in your JSON.
Example
import DS from 'ember-data';
import { underscore } from '@ember/string';
export default DS.RESTSerializer.extend({
keyForAttribute(attr, method) {
return underscore(attr).toUpperCase();
}
});
Parameters:
-
key
String -
method
String
Returns:
normalized key
keyForLink
-
key
-
kind
keyForLink
can be used to define a custom key when deserializing link
properties.
Parameters:
-
key
String -
kind
StringbelongsTo
orhasMany
Returns:
normalized key
keyForRelationship
-
key
-
typeClass
-
method
keyForRelationship
can be used to define a custom key when
serializing and deserializing relationship properties. By default
JSONSerializer
does not provide an implementation of this method.
Example
import DS from 'ember-data';
import { underscore } from '@ember/string';
export default DS.JSONSerializer.extend({
keyForRelationship(key, relationship, method) {
return rel_${underscore(key)}
;
}
});
Parameters:
-
key
String -
typeClass
String -
method
String
Returns:
normalized key
modelNameFromPayloadKey
-
key
Parameters:
-
key
String
Returns:
the model's modelName
normalize
-
typeClass
-
hash
Normalizes a part of the JSON payload returned by the server. You should override this method, munge the hash and call super if you have generic normalization to do.
It takes the type of the record that is being normalized (as a DS.Model class), the property where the hash was originally found, and the hash to normalize.
You can use this method, for example, to normalize underscored keys to camelized or other general-purpose normalizations.
Example
import DS from 'ember-data';
import { underscore } from '@ember/string';
import { get } from '@ember/object';
export default DS.JSONSerializer.extend({
normalize(typeClass, hash) {
var fields = get(typeClass, 'fields');
fields.forEach(function(type, field) {
var payloadField = underscore(field);
if (field === payloadField) { return; }
hash[field] = hash[payloadField];
delete hash[payloadField];
});
return this._super.apply(this, arguments);
}
});
Parameters:
-
typeClass
DS.Model -
hash
Object
Returns:
normalizeArrayResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeCreateRecordResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeDeleteRecordResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeFindAllResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeFindBelongsToResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeFindHasManyResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeFindManyResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeFindRecordResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeQueryRecordResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeQueryResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeRelationships
()
private
normalizeResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
The normalizeResponse
method is used to normalize a payload from the
server to a JSON-API Document.
http://jsonapi.org/format/#document-structure
This method delegates to a more specific normalize method based on
the requestType
.
To override this method with a custom one, make sure to call
return this._super(store, primaryModelClass, payload, id, requestType)
with your
pre-processed data.
Here's an example of using normalizeResponse
manually:
socket.on('message', function(message) {
var data = message.data;
var modelClass = store.modelFor(data.modelName);
var serializer = store.serializerFor(data.modelName);
var normalized = serializer.normalizeSingleResponse(store, modelClass, data, data.id);
store.push(normalized);
});
Parameters:
Returns:
JSON-API Document
normalizeSaveResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeSingleResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeUpdateRecordResponse
-
store
-
primaryModelClass
-
payload
-
id
-
requestType
Parameters:
Returns:
JSON-API Document
normalizeUsingDeclaredMapping
()
private
serialize
-
snapshot
-
options
Called when a record is saved in order to convert the record into JSON.
By default, it creates a JSON object with a key for each attribute and belongsTo relationship.
For example, consider this model:
import DS from 'ember-data';
export default DS.Model.extend({
title: DS.attr(),
body: DS.attr(),
author: DS.belongsTo('user')
});
The default serialization would create a JSON object like:
{
"title": "Rails is unagi",
"body": "Rails? Omakase? O_O",
"author": 12
}
By default, attributes are passed through as-is, unless
you specified an attribute type (DS.attr('date')
). If
you specify a transform, the JavaScript value will be
serialized when inserted into the JSON hash.
By default, belongs-to relationships are converted into IDs when inserted into the JSON hash.
IDs
serialize
takes an options hash with a single option:
includeId
. If this option is true
, serialize
will,
by default include the ID in the JSON object it builds.
The adapter passes in includeId: true
when serializing
a record for createRecord
, but not for updateRecord
.
Customization
Your server may expect a different JSON format than the built-in serialization format.
In that case, you can implement serialize
yourself and
return a JSON hash of your choosing.
import DS from 'ember-data';
export default DS.JSONSerializer.extend({
serialize(snapshot, options) {
var json = {
POST_TTL: snapshot.attr('title'),
POST_BDY: snapshot.attr('body'),
POST_CMS: snapshot.hasMany('comments', { ids: true })
};
if (options.includeId) {
json.POST_ID_ = snapshot.id;
}
return json;
}
});
Customizing an App-Wide Serializer
If you want to define a serializer for your entire
application, you'll probably want to use eachAttribute
and eachRelationship
on the record.
import DS from 'ember-data';
import { singularize } from 'ember-inflector';
export default DS.JSONSerializer.extend({
serialize(snapshot, options) {
var json = {};
snapshot.eachAttribute(function(name) {
json[serverAttributeName(name)] = snapshot.attr(name);
});
snapshot.eachRelationship(function(name, relationship) {
if (relationship.kind === 'hasMany') {
json[serverHasManyName(name)] = snapshot.hasMany(name, { ids: true });
}
});
if (options.includeId) {
json.ID_ = snapshot.id;
}
return json;
}
});
function serverAttributeName(attribute) {
return attribute.underscore().toUpperCase();
}
function serverHasManyName(name) {
return serverAttributeName(singularize(name)) + "_IDS";
}
This serializer will generate JSON that looks like this:
{
"TITLE": "Rails is omakase",
"BODY": "Yep. Omakase.",
"COMMENT_IDS": [ 1, 2, 3 ]
}
Tweaking the Default JSON
If you just want to do some small tweaks on the default JSON, you can call super first and make the tweaks on the returned JSON.
import DS from 'ember-data';
export default DS.JSONSerializer.extend({
serialize(snapshot, options) {
var json = this._super(...arguments);
json.subject = json.title;
delete json.title;
return json;
}
});
Parameters:
-
snapshot
DS.Snapshot -
options
Object
Returns:
json
serializeAttribute
-
snapshot
-
json
-
key
-
attribute
serializeAttribute
can be used to customize how DS.attr
properties are serialized
For example if you wanted to ensure all your attributes were always
serialized as properties on an attributes
object you could
write:
import DS from 'ember-data';
export default DS.JSONSerializer.extend({
serializeAttribute(snapshot, json, key, attributes) {
json.attributes = json.attributes || {};
this._super(snapshot, json.attributes, key, attributes);
}
});
Parameters:
-
snapshot
DS.Snapshot -
json
Object -
key
String -
attribute
Object
serializeBelongsTo
-
snapshot
-
json
-
relationship
serializeBelongsTo
can be used to customize how DS.belongsTo
properties are serialized.
Example
import DS from 'ember-data';
import { isNone } from '@ember/utils';
export default DS.JSONSerializer.extend({
serializeBelongsTo(snapshot, json, relationship) {
var key = relationship.key;
var belongsTo = snapshot.belongsTo(key);
key = this.keyForRelationship ? this.keyForRelationship(key, "belongsTo", "serialize") : key;
json[key] = isNone(belongsTo) ? belongsTo : belongsTo.record.toJSON();
}
});
Parameters:
-
snapshot
DS.Snapshot -
json
Object -
relationship
Object
serializeHasMany
-
snapshot
-
json
-
relationship
serializeHasMany
can be used to customize how DS.hasMany
properties are serialized.
Example
import DS from 'ember-data';
export default DS.JSONSerializer.extend({
serializeHasMany(snapshot, json, relationship) {
var key = relationship.key;
if (key === 'comments') {
return;
} else {
this._super(...arguments);
}
}
});
Parameters:
-
snapshot
DS.Snapshot -
json
Object -
relationship
Object
serializeIntoHash
-
hash
-
typeClass
-
snapshot
-
options
You can use this method to customize how a serialized record is added to the complete JSON hash to be sent to the server. By default the JSON Serializer does not namespace the payload and just sends the raw serialized JSON object. If your server expects namespaced keys, you should consider using the RESTSerializer. Otherwise you can override this method to customize how the record is added to the hash. The hash property should be modified by reference.
For example, your server may expect underscored root objects.
import DS from 'ember-data';
import { decamelize } from '@ember/string';
export default DS.RESTSerializer.extend({
serializeIntoHash(data, type, snapshot, options) {
var root = decamelize(type.modelName);
data[root] = this.serialize(snapshot, options);
}
});
Parameters:
-
hash
Object -
typeClass
DS.Model -
snapshot
DS.Snapshot -
options
Object
serializePolymorphicType
-
snapshot
-
json
-
relationship
You can use this method to customize how polymorphic objects are
serialized. Objects are considered to be polymorphic if
{ polymorphic: true }
is pass as the second argument to the
DS.belongsTo
function.
Example
import DS from 'ember-data';
import { isNone } from '@ember/utils';
export default DS.JSONSerializer.extend({
serializePolymorphicType(snapshot, json, relationship) {
var key = relationship.key;
var belongsTo = snapshot.belongsTo(key);
key = this.keyForAttribute ? this.keyForAttribute(key, 'serialize') : key;
if (isNone(belongsTo)) {
json[key + '_type'] = null;
} else {
json[key + '_type'] = belongsTo.modelName;
}
}
});
Parameters:
-
snapshot
DS.Snapshot -
json
Object -
relationship
Object
shouldSerializeHasMany
-
snapshot
-
key
-
relationshipType
Check if the given hasMany relationship should be serialized
By default only many-to-many and many-to-none relationships are serialized.
This could be configured per relationship by Serializer's attrs
object.
Parameters:
-
snapshot
DS.Snapshot -
key
String -
relationshipType
String
Returns:
true if the hasMany relationship should be serialized
transformFor
-
attributeType
-
skipAssertion
Parameters:
-
attributeType
String -
skipAssertion
Boolean
Returns:
transform
Properties
attrs
Object
The attrs
object can be used to declare a simple mapping between
property names on DS.Model
records and payload keys in the
serialized JSON object representing the record. An object with the
property key
can also be used to designate the attribute's key on
the response payload.
Example
import DS from 'ember-data';
export default DS.Model.extend({
firstName: DS.attr('string'),
lastName: DS.attr('string'),
occupation: DS.attr('string'),
admin: DS.attr('boolean')
});
import DS from 'ember-data';
export default DS.JSONSerializer.extend({
attrs: {
admin: 'is_admin',
occupation: { key: 'career' }
}
});
You can also remove attributes and relationships by setting the serialize
key to false
in your mapping object.
Example
import DS from 'ember-data';
export default DS.JSONSerializer.extend({
attrs: {
admin: { serialize: false },
occupation: { key: 'career' }
}
});
When serialized:
{
"firstName": "Harry",
"lastName": "Houdini",
"career": "magician"
}
Note that the admin
is now not included in the payload.
Setting serialize
to true
enforces serialization for hasMany
relationships even if it's neither a many-to-many nor many-to-none
relationship.
primaryKey
String
The primaryKey
is used when serializing and deserializing
data. Ember Data always uses the id
property to store the id of
the record. The external source may not always follow this
convention. In these cases it is useful to override the
primaryKey
property to match the primaryKey
of your external
store.
Example
import DS from 'ember-data';
export default DS.JSONSerializer.extend({
primaryKey: '_id'
});
Default: 'id'
store
DS.Store
public
store
property is the application's store
that contains
all records. It can be used to look up serializers for other model
types that may be nested inside the payload response.
Example:
`
js
Serializer.extend({
extractRelationship(relationshipModelName, relationshipHash) {
var modelClass = this.store.modelFor(relationshipModelName);
var relationshipSerializer = this.store.serializerFor(relationshipModelName);
return relationshipSerializer.normalize(modelClass, relationshipHash);
}
});
`