Refactor update creation api

This merge request does the following:

• Raise DRF errors rather than returning response to take advantage of the DRF exception handling mechanism
• Create serialisers for PUT request to simplify the code
• Improve validation checks in several places
• Fixes several issues in DRF infrastructure uses
• Fixes JSON fields handling
• Remove routes that do no fully qualify objects
• Implement a custom DRF exception handler that will allow to log errors
• Improve testing
• Improve permission management

beat/web/common/fields.py

@@ -25,22 +25,22 @@
 #                                                                             #
 ###############################################################################
 
-from rest_framework import serializers
-from django.utils import six
+import simplejson as json
 
-import simplejson
+from rest_framework import serializers
+from rest_framework.fields import JSONField as drf_JSONField
 
 
 class StringListField(serializers.ListField):
     child = serializers.CharField()
 
 
-class JSONSerializerField(serializers.Field):
-    """ Serializer for JSONField -- required to make field writable"""
+class JSONField(drf_JSONField):
     def to_internal_value(self, data):
-        if isinstance(data, six.string_types):
-            return simplejson.loads(data)
-        return data
+        if isinstance(data, str):
+            try:
+                data = json.loads(data)
+            except json.errors.JSONDecodeError:
+                self.fail("invalid")
 
-    def to_representation(self, value):
-        return value
+        return super().to_internal_value(data)