json_serializer.js

import Serializer from "ember-data/system/serializer";
var camelize = Ember.String.camelize;
import { singularize } from "ember-inflector/system/string";

var get = Ember.get;
var isNone = Ember.isNone;
var map = Ember.ArrayPolyfills.map;
var merge = Ember.merge;

/**
  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.

  For maximum performance Ember Data recommends you use the
  [RESTSerializer](DS.RESTSerializer.html) or one of its subclasses.

  `JSONSerializer` is useful for simpler or legacy backends that may
  not support the http://jsonapi.org/ spec.

  @class JSONSerializer
  @namespace DS
  @extends DS.Serializer
*/
export default Serializer.extend({
  /**
    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

    ```javascript
    App.ApplicationSerializer = DS.JSONSerializer.extend({
      primaryKey: '_id'
    });
    ```

    @property primaryKey
    @type {String}
    @default 'id'
  */
  primaryKey: 'id',

  /**
    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

    ```javascript
    App.Person = DS.Model.extend({
      firstName: DS.attr('string'),
      lastName: DS.attr('string'),
      occupation: DS.attr('string'),
      admin: DS.attr('boolean')
    });

    App.PersonSerializer = DS.JSONSerializer.extend({
      attrs: {
        admin: 'is_admin',
        occupation: {key: 'career'}
      }
    });
    ```

    You can also remove attributes by setting the `serialize` key to
    false in your mapping object.

    Example

    ```javascript
    App.PersonSerializer = DS.JSONSerializer.extend({
      attrs: {
        admin: {serialize: false},
        occupation: {key: 'career'}
      }
    });
    ```

    When serialized:

    ```javascript
    {
      "career": "magician"
    }
    ```

    Note that the `admin` is now not included in the payload.

    @property attrs
    @type {Object}
  */

  /**
   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.

   @method applyTransforms
   @private
   @param {subclass of DS.Model} type
   @param {Object} data The data to transform
   @return {Object} data The transformed data object
  */
  applyTransforms: function(type, data) {
    type.eachTransformedAttribute(function applyTransform(key, type) {
      if (!data.hasOwnProperty(key)) { return; }

      var transform = this.transformFor(type);
      data[key] = transform.deserialize(data[key]);
    }, this);

    return data;
  },

  /**
    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

    ```javascript
    App.ApplicationSerializer = DS.JSONSerializer.extend({
      normalize: function(type, hash) {
        var fields = Ember.get(type, 'fields');
        fields.forEach(function(field) {
          var payloadField = Ember.String.underscore(field);
          if (field === payloadField) { return; }

          hash[field] = hash[payloadField];
          delete hash[payloadField];
        });
        return this._super.apply(this, arguments);
      }
    });
    ```

    @method normalize
    @param {subclass of DS.Model} type
    @param {Object} hash
    @return {Object}
  */
  normalize: function(type, hash) {
    if (!hash) { return hash; }

    this.normalizeId(hash);
    this.normalizeAttributes(type, hash);
    this.normalizeRelationships(type, hash);

    this.normalizeUsingDeclaredMapping(type, hash);
    this.applyTransforms(type, hash);
    return hash;
  },

  /**
    You can use this method to normalize all payloads, regardless of whether they
    represent single records or an array.

    For example, you might want to remove some extraneous data from the payload:

    ```js
    App.ApplicationSerializer = DS.JSONSerializer.extend({
      normalizePayload: function(payload) {
        delete payload.version;
        delete payload.status;
        return payload;
      }
    });
    ```

    @method normalizePayload
    @param {Object} payload
    @return {Object} the normalized payload
  */
  normalizePayload: function(payload) {
    return payload;
  },

  /**
    @method normalizeAttributes
    @private
  */
  normalizeAttributes: function(type, hash) {
    var payloadKey;

    if (this.keyForAttribute) {
      type.eachAttribute(function(key) {
        payloadKey = this.keyForAttribute(key);
        if (key === payloadKey) { return; }
        if (!hash.hasOwnProperty(payloadKey)) { return; }

        hash[key] = hash[payloadKey];
        delete hash[payloadKey];
      }, this);
    }
  },

  /**
    @method normalizeRelationships
    @private
  */
  normalizeRelationships: function(type, hash) {
    var payloadKey;

    if (this.keyForRelationship) {
      type.eachRelationship(function(key, relationship) {
        payloadKey = this.keyForRelationship(key, relationship.kind);
        if (key === payloadKey) { return; }
        if (!hash.hasOwnProperty(payloadKey)) { return; }

        hash[key] = hash[payloadKey];
        delete hash[payloadKey];
      }, this);
    }
  },

  /**
    @method normalizeUsingDeclaredMapping
    @private
  */
  normalizeUsingDeclaredMapping: function(type, hash) {
    var attrs = get(this, 'attrs');
    var payloadKey, key;

    if (attrs) {
      for (key in attrs) {
        payloadKey = this._getMappedKey(key);
        if (!hash.hasOwnProperty(payloadKey)) { continue; }

        if (payloadKey !== key) {
          hash[key] = hash[payloadKey];
          delete hash[payloadKey];
        }
      }
    }
  },

  /**
    @method normalizeId
    @private
  */
  normalizeId: function(hash) {
    var primaryKey = get(this, 'primaryKey');

    if (primaryKey === 'id') { return; }

    hash.id = hash[primaryKey];
    delete hash[primaryKey];
  },

  /**
    @method normalizeErrors
    @private
  */
  normalizeErrors: function(type, hash) {
    this.normalizeId(hash);
    this.normalizeAttributes(type, hash);
    this.normalizeRelationships(type, hash);
  },

  /**
    Looks up the property key that was set by the custom `attr` mapping
    passed to the serializer.

    @method _getMappedKey
    @private
    @param {String} key
    @return {String} key
  */
  _getMappedKey: function(key) {
    var attrs = get(this, 'attrs');
    var mappedKey;
    if (attrs && attrs[key]) {
      mappedKey = attrs[key];
      //We need to account for both the {title: 'post_title'} and
      //{title: {key: 'post_title'}} forms
      if (mappedKey.key) {
        mappedKey = mappedKey.key;
      }
      if (typeof mappedKey === 'string') {
        key = mappedKey;
      }
    }

    return key;
  },

  /**
    Check attrs.key.serialize property to inform if the `key`
    can be serialized

    @method _canSerialize
    @private
    @param {String} key
    @return {boolean} true if the key can be serialized
  */
  _canSerialize: function(key) {
    var attrs = get(this, 'attrs');

    return !attrs || !attrs[key] || attrs[key].serialize !== false;
  },

  // SERIALIZE
  /**
    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:

    ```javascript
    App.Comment = DS.Model.extend({
      title: DS.attr(),
      body: DS.attr(),

      author: DS.belongsTo('user')
    });
    ```

    The default serialization would create a JSON object like:

    ```javascript
    {
      "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.

    ```javascript
    App.PostSerializer = DS.JSONSerializer.extend({
      serialize: function(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.

    ```javascript
    App.ApplicationSerializer = DS.JSONSerializer.extend({
      serialize: function(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(name.singularize()) + "_IDS";
    }
    ```

    This serializer will generate JSON that looks like this:

    ```javascript
    {
      "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.

    ```javascript
    App.PostSerializer = DS.JSONSerializer.extend({
      serialize: function(snapshot, options) {
        var json = this._super.apply(this, arguments);

        json.subject = json.title;
        delete json.title;

        return json;
      }
    });
    ```

    @method serialize
    @param {DS.Snapshot} snapshot
    @param {Object} options
    @return {Object} json
  */
  serialize: function(snapshot, options) {
    var json = {};

    if (options && options.includeId) {
      var id = snapshot.id;

      if (id) {
        json[get(this, 'primaryKey')] = id;
      }
    }

    snapshot.eachAttribute(function(key, attribute) {
      this.serializeAttribute(snapshot, json, key, attribute);
    }, this);

    snapshot.eachRelationship(function(key, relationship) {
      if (relationship.kind === 'belongsTo') {
        this.serializeBelongsTo(snapshot, json, relationship);
      } else if (relationship.kind === 'hasMany') {
        this.serializeHasMany(snapshot, json, relationship);
      }
    }, this);

    return json;
  },

  /**
    Serialize a model snapshot into a server request payload.

    By default the JSON Serializer does not namespace
    payloads, instead a "raw" serialized object is sent. For example:

    ```js
    {
      id: 'car-one',
      speed: 'fast'
    }
    ```

    Note the lack of a namespace, and of any information about what
    model this payload refers to.

    If your server expects namespaced payloads, you should consider using the RESTSerializer.

    You can also override this method to customize serialization behavior.
    For example, your server may expect underscored model namespaces:

    ```js
    App.ApplicationSerializer = DS.RESTSerializer.extend({
      serializeIntoHash: function(data, type, snapshot, options) {
        // type.typeKey is a model name with formatting decided by your
        // application container. In globals mode, ususally camelCase. In
        // Ember-CLI, usually dasherize-case.
        var root = Ember.String.decamelize(type.typeKey);
        data[root] = this.serialize(snapshot, options);
      }
    });
    ```

    @method serializeIntoHash
    @param {Object} hash
    @param {subclass of DS.Model} type
    @param {DS.Snapshot} snapshot
    @param {Object} options
  */
  serializeIntoHash: function(hash, type, snapshot, options) {
    merge(hash, this.serialize(snapshot, options));
  },

  /**
   `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:

   ```javascript
   App.ApplicationSerializer = DS.JSONSerializer.extend({
     serializeAttribute: function(snapshot, json, key, attributes) {
       json.attributes = json.attributes || {};
       this._super(snapshot, json.attributes, key, attributes);
     }
   });
   ```

   @method serializeAttribute
   @param {DS.Snapshot} snapshot
   @param {Object} json
   @param {String} key
   @param {Object} attribute
  */
  serializeAttribute: function(snapshot, json, key, attribute) {
    var type = attribute.type;

    if (this._canSerialize(key)) {
      var value = snapshot.attr(key);
      if (type) {
        var transform = this.transformFor(type);
        value = transform.serialize(value);
      }

      // if provided, use the mapping provided by `attrs` in
      // the serializer
      var payloadKey =  this._getMappedKey(key);

      if (payloadKey === key && this.keyForAttribute) {
        payloadKey = this.keyForAttribute(key);
      }

      json[payloadKey] = value;
    }
  },

  /**
   `serializeBelongsTo` can be used to customize how `DS.belongsTo`
   properties are serialized.

   Example

   ```javascript
   App.PostSerializer = DS.JSONSerializer.extend({
     serializeBelongsTo: function(snapshot, json, relationship) {
       var key = relationship.key;

       var belongsTo = snapshot.belongsTo(key);

       key = this.keyForRelationship ? this.keyForRelationship(key, "belongsTo") : key;

       json[key] = Ember.isNone(belongsTo) ? belongsTo : belongsTo.record.toJSON();
     }
   });
   ```

   @method serializeBelongsTo
   @param {DS.Snapshot} snapshot
   @param {Object} json
   @param {Object} relationship
  */
  serializeBelongsTo: function(snapshot, json, relationship) {
    var key = relationship.key;

    if (this._canSerialize(key)) {
      var belongsToId = snapshot.belongsTo(key, { id: true });

      // if provided, use the mapping provided by `attrs` in
      // the serializer
      var payloadKey = this._getMappedKey(key);
      if (payloadKey === key && this.keyForRelationship) {
        payloadKey = this.keyForRelationship(key, "belongsTo");
      }

      //Need to check whether the id is there for new&async records
      if (isNone(belongsToId)) {
        json[payloadKey] = null;
      } else {
        json[payloadKey] = belongsToId;
      }

      if (relationship.options.polymorphic) {
        this.serializePolymorphicType(snapshot, json, relationship);
      }
    }
  },

  /**
   `serializeHasMany` can be used to customize how `DS.hasMany`
   properties are serialized.

   Example

   ```javascript
   App.PostSerializer = DS.JSONSerializer.extend({
     serializeHasMany: function(snapshot, json, relationship) {
       var key = relationship.key;
       if (key === 'comments') {
         return;
       } else {
         this._super.apply(this, arguments);
       }
     }
   });
   ```

   @method serializeHasMany
   @param {DS.Snapshot} snapshot
   @param {Object} json
   @param {Object} relationship
  */
  serializeHasMany: function(snapshot, json, relationship) {
    var key = relationship.key;

    if (this._canSerialize(key)) {
      var payloadKey;

      // if provided, use the mapping provided by `attrs` in
      // the serializer
      payloadKey = this._getMappedKey(key);
      if (payloadKey === key && this.keyForRelationship) {
        payloadKey = this.keyForRelationship(key, "hasMany");
      }

      var relationshipType = snapshot.type.determineRelationshipType(relationship);

      if (relationshipType === 'manyToNone' || relationshipType === 'manyToMany') {
        json[payloadKey] = snapshot.hasMany(key, { ids: true });
        // TODO support for polymorphic manyToNone and manyToMany relationships
      }
    }
  },

  /**
    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

    ```javascript
    App.CommentSerializer = DS.JSONSerializer.extend({
      serializePolymorphicType: function(snapshot, json, relationship) {
        var key = relationship.key,
            belongsTo = snapshot.belongsTo(key);
        key = this.keyForAttribute ? this.keyForAttribute(key) : key;

        if (Ember.isNone(belongsTo)) {
          json[key + "_type"] = null;
        } else {
          json[key + "_type"] = belongsTo.typeKey;
        }
      }
    });
    ```

    The default behavior of this method is to not serialize
    type data for polymorphic relationships.

    @method serializePolymorphicType
    @param {DS.Snapshot} snapshot
    @param {Object} json
    @param {Object} relationship
  */
  serializePolymorphicType: Ember.K,

  // EXTRACT

  /**
    The `extract` method is used to deserialize payload data from the
    server. By default the `JSONSerializer` does not push the records
    into the store. However records that subclass `JSONSerializer`
    such as the `RESTSerializer` may push records into the store as
    part of the extract call.

    This method delegates to a more specific extract method based on
    the `requestType`.

    To override this method with a custom one, make sure to call
    `this._super(store, type, payload, id, requestType)` with your
    pre-processed data.

    Here's an example of using `extract` manually:

    ```javascript
    socket.on('message', function(message) {
      var data = message.data;
      var type = store.modelFor(message.modelName);
      var serializer = store.serializerFor(type.typeKey);
      var record = serializer.extract(store, type, data, data.id, 'single');

      store.push(message.modelName, record);
    });
    ```

    @method extract
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Object} json The deserialized payload
  */
  extract: function(store, type, payload, id, requestType) {
    this.extractMeta(store, type, payload);

    var specificExtract = "extract" + requestType.charAt(0).toUpperCase() + requestType.substr(1);
    return this[specificExtract](store, type, payload, id, requestType);
  },

  /**
    `extractFindAll` is a hook into the extract method used when a
    call is made to `DS.Store#findAll`. By default this method is an
    alias for [extractArray](#method_extractArray).

    @method extractFindAll
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Array} array An array of deserialized objects
  */
  extractFindAll: function(store, type, payload, id, requestType) {
    return this.extractArray(store, type, payload, id, requestType);
  },
  /**
    `extractFindQuery` is a hook into the extract method used when a
    call is made to `DS.Store#findQuery`. By default this method is an
    alias for [extractArray](#method_extractArray).

    @method extractFindQuery
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Array} array An array of deserialized objects
  */
  extractFindQuery: function(store, type, payload, id, requestType) {
    return this.extractArray(store, type, payload, id, requestType);
  },
  /**
    `extractFindMany` is a hook into the extract method used when a
    call is made to `DS.Store#findMany`. By default this method is
    alias for [extractArray](#method_extractArray).

    @method extractFindMany
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Array} array An array of deserialized objects
  */
  extractFindMany: function(store, type, payload, id, requestType) {
    return this.extractArray(store, type, payload, id, requestType);
  },
  /**
    `extractFindHasMany` is a hook into the extract method used when a
    call is made to `DS.Store#findHasMany`. By default this method is
    alias for [extractArray](#method_extractArray).

    @method extractFindHasMany
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Array} array An array of deserialized objects
  */
  extractFindHasMany: function(store, type, payload, id, requestType) {
    return this.extractArray(store, type, payload, id, requestType);
  },

  /**
    `extractCreateRecord` is a hook into the extract method used when a
    call is made to `DS.Model#save` and the record is new. By default
    this method is alias for [extractSave](#method_extractSave).

    @method extractCreateRecord
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Object} json The deserialized payload
  */
  extractCreateRecord: function(store, type, payload, id, requestType) {
    return this.extractSave(store, type, payload, id, requestType);
  },
  /**
    `extractUpdateRecord` is a hook into the extract method used when
    a call is made to `DS.Model#save` and the record has been updated.
    By default this method is alias for [extractSave](#method_extractSave).

    @method extractUpdateRecord
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Object} json The deserialized payload
  */
  extractUpdateRecord: function(store, type, payload, id, requestType) {
    return this.extractSave(store, type, payload, id, requestType);
  },
  /**
    `extractDeleteRecord` is a hook into the extract method used when
    a call is made to `DS.Model#save` and the record has been deleted.
    By default this method is alias for [extractSave](#method_extractSave).

    @method extractDeleteRecord
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Object} json The deserialized payload
  */
  extractDeleteRecord: function(store, type, payload, id, requestType) {
    return this.extractSave(store, type, payload, id, requestType);
  },

  /**
    `extractFind` is a hook into the extract method used when
    a call is made to `DS.Store#find`. By default this method is
    alias for [extractSingle](#method_extractSingle).

    @method extractFind
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Object} json The deserialized payload
  */
  extractFind: function(store, type, payload, id, requestType) {
    return this.extractSingle(store, type, payload, id, requestType);
  },
  /**
    `extractFindBelongsTo` is a hook into the extract method used when
    a call is made to `DS.Store#findBelongsTo`. By default this method is
    alias for [extractSingle](#method_extractSingle).

    @method extractFindBelongsTo
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Object} json The deserialized payload
  */
  extractFindBelongsTo: function(store, type, payload, id, requestType) {
    return this.extractSingle(store, type, payload, id, requestType);
  },
  /**
    `extractSave` is a hook into the extract method used when a call
    is made to `DS.Model#save`. By default this method is alias
    for [extractSingle](#method_extractSingle).

    @method extractSave
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Object} json The deserialized payload
  */
  extractSave: function(store, type, payload, id, requestType) {
    return this.extractSingle(store, type, payload, id, requestType);
  },

  /**
    `extractSingle` is used to deserialize a single record returned
    from the adapter.

    Example

    ```javascript
    App.PostSerializer = DS.JSONSerializer.extend({
      extractSingle: function(store, type, payload) {
        payload.comments = payload._embedded.comment;
        delete payload._embedded;

        return this._super(store, type, payload);
      },
    });
    ```

    @method extractSingle
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Object} json The deserialized payload
  */
  extractSingle: function(store, type, payload, id, requestType) {
    payload = this.normalizePayload(payload);
    return this.normalize(type, payload);
  },

  /**
    `extractArray` is used to deserialize an array of records
    returned from the adapter.

    Example

    ```javascript
    App.PostSerializer = DS.JSONSerializer.extend({
      extractArray: function(store, type, payload) {
        return payload.map(function(json) {
          return this.extractSingle(store, type, json);
        }, this);
      }
    });
    ```

    @method extractArray
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @param {String} requestType
    @return {Array} array An array of deserialized objects
  */
  extractArray: function(store, type, arrayPayload, id, requestType) {
    var normalizedPayload = this.normalizePayload(arrayPayload);
    var serializer = this;

    return map.call(normalizedPayload, function(singlePayload) {
      return serializer.normalize(type, singlePayload);
    });
  },

  /**
    `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

    ```javascript
    App.PostSerializer = DS.JSONSerializer.extend({
      extractMeta: function(store, type, payload) {
        if (payload && payload._pagination) {
          store.setMetadataFor(type, payload._pagination);
          delete payload._pagination;
        }
      }
    });
    ```

    @method extractMeta
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
  */
  extractMeta: function(store, type, payload) {
    if (payload && payload.meta) {
      store.setMetadataFor(type, payload.meta);
      delete payload.meta;
    }
  },

  /**
    `extractErrors` is used to extract model errors when a call is made
    to `DS.Model#save` which fails with an `InvalidError`. By default
    Ember Data expects error information to be located on the `errors`
    property of the payload object.

    Example

    ```javascript
    App.PostSerializer = DS.JSONSerializer.extend({
      extractErrors: function(store, type, payload, id) {
        if (payload && typeof payload === 'object' && payload._problems) {
          payload = payload._problems;
          this.normalizeErrors(type, payload);
        }
        return payload;
      }
    });
    ```

    @method extractErrors
    @param {DS.Store} store
    @param {subclass of DS.Model} type
    @param {Object} payload
    @param {String or Number} id
    @return {Object} json The deserialized errors
  */
  extractErrors: function(store, type, payload, id) {
    if (payload && typeof payload === 'object' && payload.errors) {
      payload = payload.errors;
      this.normalizeErrors(type, payload);
    }
    return payload;
  },

  /**
   `keyForAttribute` can be used to define rules for how to convert an
   attribute name in your model to a key in your JSON.

   Example

   ```javascript
   App.ApplicationSerializer = DS.RESTSerializer.extend({
     keyForAttribute: function(attr) {
       return Ember.String.underscore(attr).toUpperCase();
     }
   });
   ```

   @method keyForAttribute
   @param {String} key
   @return {String} normalized key
  */
  keyForAttribute: function(key) {
    return key;
  },

  /**
   `keyForRelationship` can be used to define a custom key when
   serializing relationship properties. By default `JSONSerializer`
   does not provide an implementation of this method.

   Example

    ```javascript
    App.PostSerializer = DS.JSONSerializer.extend({
      keyForRelationship: function(key, relationship) {
         return 'rel_' + Ember.String.underscore(key);
      }
    });
    ```

   @method keyForRelationship
   @param {String} key
   @param {String} relationship type
   @return {String} normalized key
  */

  keyForRelationship: function(key, type) {
    return key;
  },

  // HELPERS

  /**
   @method transformFor
   @private
   @param {String} attributeType
   @param {Boolean} skipAssertion
   @return {DS.Transform} transform
  */
  transformFor: function(attributeType, skipAssertion) {
    var transform = this.container.lookup('transform:' + attributeType);
    Ember.assert("Unable to find transform for '" + attributeType + "'", skipAssertion || !!transform);
    return transform;
  },

  /**
    Convert an Ember-Data model type string into a type string for a request
    payload. For example, your server may expect types to be camelCased:

    ```js
    // a request payload
    {
      "fastCar": {
        "id": "1",
        "name": "corvette"
      }
    }
    ```

    The default behavior is to camelCase and singularize model keys.
    This method is used in `serializeIntoHash`, `serializePolymorphicType`
    and in the embedded records mixin.

    If you customize this behavior, keep in mind that Model naming
    conventions may vary between applications and environements, but
    will most often follow these standards:

    * Ember-CLI applications will follow the pattern: `dasherized-model-name`.
    * Globals-mode Ember applications will follow the pattern `camelCaseName`.

    @method typeForPayload
    @param {String} key
    @return {String} the model's name in your request payloads
  */
  typeForPayload: function(key) {
    return camelize(singularize(key));
  }
});