Start of Ember ActiveModel Serializer support for accepts_nested_attributes_for with deletion

application.js

//file app/serializers/application.js

import DS from "ember-data";
import Ember from "ember";

export default DS.ActiveModelSerializer.extend({

  serializeHasMany: function (record, json, relationship) {
    var key = relationship.key;
    var hasManyRecords = Ember.get(record, key);

    if (!hasManyRecords) { return; }
     
    // Embed hasMany relationship if records exist
    if (relationship.options.embedded === 'always') {
      var embedKey = key + "_attributes";
      json[embedKey] = [];
      hasManyRecords.forEach(function(item){
          json[embedKey].push(item.serialize({ includeId: true }));
      });

      this.addDeletedRecords(record, key, json[embedKey]);

      this.willCommitDeletedRecords(record);
      record.one('didCommit', this, 'didCommitDeletedRecords');
      record.one('becameError', this, 'didFailToCommitDeletedRecords');
    }
    // Fallback to default serialization behavior
    else {
      var payloadKey = this.keyForRelationship(key, "hasMany");
      json[payloadKey] = hasManyRecords.mapBy('id');
    }
  },

  serializeBelongsTo: function(record, json, relationship) {
    var key = relationship.key;
    var belongsToRecord = Ember.get(record, key);
    var embedKey = key + "_attributes";
     
    if (belongsToRecord && relationship.options.embedded === 'always') {
        json[embedKey] = belongsToRecord.serialize();
    }
    else {
        return this._super(record, json, relationship);
    }
  },


  addDeletedRecords: function (record, key, jsonArray) {
    var deletedRecords = record.get(key + '.deleted');
    if (deletedRecords) {
      deletedRecords.forEach(function (deletedRecord) {
        if (!deletedRecord.get('isNew')) {
          var serialized;
          if (deletedRecord.get('isSoftDeleted')) {
            serialized = deletedRecord.serialize({ includeId: true });
          } else {
            serialized = { id: deletedRecord.get('id') };
          }

          serialized._destroy = true;

          jsonArray.pushObject(serialized);
        }
      });
    }
  },

  willCommitDeletedRecords: function (record) {
    function willCommitDeletedRecord(record) {
      record.send('willCommit');
    }

    function willCommitDeletedRecords(name) {
      var deletedKey = name + '.deleted';
      var deletedRecords = record.get(deletedKey);
      if (deletedRecords) {
        deletedRecords.forEach(willCommitDeletedRecord);
      }
    }
    record.eachRelationship(willCommitDeletedRecords);
  },

  didCommitDeletedRecords: function (record) {
    function didCommitDeletedRecord(record) {
      record.send('didCommit');
      record.unloadRecord();
    }

    function didCommitDeletedRecords(name) {
      var deletedKey = name + '.deleted';
      var deletedRecords = record.get(deletedKey);
      if (deletedRecords) {
        deletedRecords.forEach(didCommitDeletedRecord);
        deletedRecords.clear();
      }
    }
    record.eachRelationship(didCommitDeletedRecords);
  },

  didFailToCommitDeletedRecords: function (/* record */) {
    
  },
});

enterprise.js

//file app/models/enterprise.js showing syntax for embedding record for accepts_nested_attributes_for

```js
import DS 'ember-data';

export default DS.Model.extend({
    archive: belongsTo('archive', {embedded:'always'})
});
```