Deprecation Guide for RESTSerializer.keyForPolymorphicType

Previous versions of the RESTSerializer relied on keyForAttribute to determine the type key used for serializing polymorphic relationships. This behavior has been deprecated in favor of using keyForPolymorphicType. The benefit of having this additional hook is that you can customize the type key separately from the key used for the relationship.

For example, given the following model:

import DS from 'ember-data';

export default DS.Model.extend({
  commentable: belongsTo('commentable', { polymorphic: true }),
  body: DS.attr('string')
});

When using the RESTSerializer, Ember Data expects a payload that looks similar the following:

{
  "comment": {
    "id": "1",
    "commentable": "123",
    "commentableType": "movie", // ${keyForAttribute}Type
    "body": "I'll be back"
  },
  "movie": {
    "id": "123",
    "title": "The Terminator"
  }
}

If your API instead responds with a key that doesn't follow the pattern of ${keyForAttribute}Type:

{
  "comment": {
    "id": "1",
    "commentable": "123",
    "commentKind": "movie", // custom keyForPolymorphicType needed
    "body": "I'll be back"
  },
  "movie": {
    "id": "123",
    "title": "The Terminator"
  }
}

You can now override the keyForPolymorphicType hook in your serializer to accommodate:

import DS from 'ember-data';

export default DS.RESTSerializer.extend({
  keyForPolymorphicType: function() {
    return 'commentKind';
  }
});