keyForId() {
    return this.primaryKey;
  }
Used to customize how a model's primary key is formatted in your JSON payload.

    By default, this is 'id'

    ```
    GET /authors/1

    {
      author: {
        id: '1',
        firstName: 'Link',
        lastName: 'The WoodElf'
      }
    }
    ```

    If your API expects a different primary key, you could write the following:

    ```js
    // serializers/application.js
    export default Serializer.extend({
      keyForId() {
        return 'authorId';
      }
    });
    ```

    Now the response would look like:

    ```
    {
      author: {
        authorId: '1',
        firstName: 'Link',
        lastName: 'The WoodElf'
      }
    }
    ```

    See the property `primaryKey` for a shorthand way of doing this on a model serializer

    @method keyForId
    @public