How to use the @ember-data/serializer/json.extend function in @ember-data/serializer

import JSONSerializer from '@ember-data/serializer/json';
import { underscore } from '@ember/string';

export default JSONSerializer.extend({
  // Use camel-cased attribute names in the JS models, but underscore the
  // attribute names for any server-side communication.
  keyForAttribute(attr) {
    return underscore(attr);
  },

  // For single records, look for the data under the customizable
  // "singlePayloadKey" attribute name on the response.
  normalizeSingleResponse(store, primaryModelClass, payload, id, requestType) {
    let key = primaryModelClass.singlePayloadKey;
    if(key) {
      payload = payload[key];
    }

    return this._super(store, primaryModelClass, payload, id, requestType);
  },

extractRelationship(relationshipHash) {
      let normalizedRelationship = this._super(...arguments);

      // Customize relationship meta
      normalizedRelationship.meta = camelCaseKeys(normalizedRelationship.meta);

      return normalizedRelationship;
    }
  });

@since 1.13.0 @class JSONAPISerializer @extends JSONSerializer / const JSONAPISerializer = JSONSerializer.extend({ /* @method _normalizeDocumentHelper @param {Object} documentHash @return {Object} @private */ _normalizeDocumentHelper(documentHash) { if (typeOf(documentHash.data) === 'object') { documentHash.data = this._normalizeResourceHelper(documentHash.data); } else if (Array.isArray(documentHash.data)) { let ret = new Array(documentHash.data.length);

  for (let i = 0; i < documentHash.data.length; i++) {
    let data = documentHash.data[i];
    ret[i] = this._normalizeResourceHelper(data);
  }

import JSONSerializer from '@ember-data/serializer/json';
import { EmbeddedRecordsMixin } from '@ember-data/serializer/rest';

export default JSONSerializer.extend(EmbeddedRecordsMixin, {});

export default RESTSerializer.extend({
    keyForAttribute(attr, method) {
      return underscore(attr).toUpperCase();
    }
  });

You can also implement keyForRelationship, which takes the name of the relationship as the first parameter, the kind of relationship (hasMany or belongsTo) as the second parameter, and the method (serialize or deserialize) as the third parameter.

@class RESTSerializer @extends JSONSerializer / const RESTSerializer = JSONSerializer.extend({ /* keyForPolymorphicType can be used to define a custom key when serializing and deserializing a polymorphic type. By default, the returned key is ${key}Type.

Example

```app/serializers/post.js
import RESTSerializer from '@ember-data/serializer/rest';

export default RESTSerializer.extend({
  keyForPolymorphicType(key, relationship) {
    var relationshipKey = this.keyForRelationship(key);

    return 'type-' + relationshipKey;
  }