Ember Data 2.6, a minor version release of Ember Data, is
released. This release represents the work of over 22 direct
contributors, and over 85 commits.
Ember Data 2.7 beta.1, the branch of Ember Data that will be released
as stable in roughly six weeks, is also being released.
Changes in Ember Data 2.6

• ds-serialize-ids-and-types

Enables a new ids-and-type strategy (in addition to the already existing ids and records) for
serializing has many relationships using the DS.EmbeddedRecordsMixin that will include both
id and type of each model as an object.
For instance, if a user has many pets, which is a polymorphic relationship, the generated payload would be:
{
"user": {
"id": "1"
"name": "Bertin Osborne",
"pets": [
{ "id": "1", "type": "Cat" },
{ "id": "2", "type": "Parrot"}
]
}
}


This is particularly useful for polymorphic relationships not backed
by STI
when just including the id of the records is not enough.
Thanks to @cibernox for
implementing this feature.
Upcoming Features in Ember Data 2.7.beta-1
ds-boolean-transform-allow-null #4022
Allow null/undefined values for boolean attributes via attr('boolean', { allowNull: true })
// app/models/user.js
import Model from 'ember-data/model';
import attr from 'ember-data/attr';

export default Model.extend({
email: attr('string'),
username: attr('string'),
wantsWeeklyEmail: attr('boolean', { allowNull: true })
});

ds-improved-ajax #3099
Though ajax() (and ajaxOptions()) of DS.RESTAdapter are marked as
private, they have been overwritten in many applications, since there is
currently no other way to customize the request.
This feature adds new public methods to DS.RESTAdapter, which allow to
customize the properties of a request:

• methodForRequest to get the HTTP verb
• urlForRequest to get the URL
• headersForRequest to get the headers
• dataForRequest to get the data (query params or request body)

The params hash passed to those methods has all the properties with
which the corresponding find, createRecord, findQuery, … calls
have been invoked: store, type, snapshot(s), id(s) and query. The
requestType property indicates which method is requested; the possible
values are:

• createRecord
• updateRecord
• deleteRecord
• query
• queryRecord
• findRecord
• findAll
• findMany
• findHasMany
• findBelongsTo

Performing the actual AJAX request is handled by the makeRequest
method, which is similar to the existing ajax method: it makes the
request using jQuery.ajax and attaches success and failure handlers.

Say your API handles creation of resources via PUT, this can now be
customized as follows:
// adapters/application.js
import DS from 'ember-data';

export default DS.RESTAdapter.extend({
methodForRequest(params) {
if (params.requestType === 'createRecord') {
return "PUT";
}

return this._super(...arguments);
}
});

Thanks to @pangratz for
implementing this feature.
ds-links-in-record-array #4263
This feature exposes a links object on a RecordArray. This can be used to load additional links when present in the response JSON-API document.
store.query('post', { isRecent: true }).then((posts) => {
posts.get('links.next');
});

Thanks to @danmcclain for
implementing this feature.
For more details on changes in the 2.7 beta, please review the
Ember Data 2.7.0-beta.1 CHANGELOG.