moving towards jsonapi

app/adapters/application.js

-import RESTAdapter from '@ember-data/adapter/rest';
+import JSONAPIAdapter from '@ember-data/adapter/json-api';
 
-export default class ApplicationAdapter extends RESTAdapter {
+export default class ApplicationAdapter extends JSONAPIAdapter {
   namespace = 'api';
   host = "http://127.0.0.1:8000"
 

app/models/content_type.js

+import Model, { attr, hasMany } from '@ember-data/model';
+
+
+class ContentTypeModel extends Model {
+  @attr app_label;
+  @attr model;
+  @hasMany('permission') permissions;
+}
+
+export default ContentTypeModel;

app/models/permission.js

+import Model, { attr, belongsTo } from '@ember-data/model';
+
+
+class PermissionModel extends Model {
+  @attr name;
+  @attr codename;
+  @belongsTo('content_type') content_type;
+}
+
+export default PermissionModel;

app/serializers/application.js

 import { underscore } from '@ember/string';
-import RESTSerializer from '@ember-data/serializer/rest';
+import JSONAPISerializer from '@ember-data/serializer/json-api';
 
-export default class ApplicationSerializer extends RESTSerializer {
+export default class ApplicationSerializer extends JSONAPISerializer {
   keyForAttribute(attr) {
     return underscore(attr);
   }