Initial backend implementation for AC-25, activity stream/audit love

awx/main/utils.py

@@ -10,6 +10,9 @@ import subprocess
 import sys
 import urlparse
 
+# Django
+from django.db.models import Model
+
 # Django REST Framework
 from rest_framework.exceptions import ParseError, PermissionDenied
 
@@ -219,3 +222,36 @@ def update_scm_url(scm_type, url, username=True, password=True):
     new_url = urlparse.urlunsplit([parts.scheme, netloc, parts.path,
                                    parts.query, parts.fragment])
     return new_url
+
+def model_instance_diff(old, new):
+    """
+    Calculate the differences between two model instances. One of the instances may be None (i.e., a newly
+    created model or deleted model). This will cause all fields with a value to have changed (from None).
+    """
+    if not(old is None or isinstance(old, Model)):
+        raise TypeError('The supplied old instance is not a valid model instance.')
+    if not(new is None or isinstance(new, Model)):
+        raise TypeError('The supplied new instance is not a valid model instance.')
+
+    diff = {}
+
+    if old is not None and new is not None:
+        fields = set(old._meta.fields + new._meta.fields)
+    elif old is not None:
+        fields = set(old._meta.fields)
+    elif new is not None:
+        fields = set(new._meta.fields)
+    else:
+        fields = set()
+
+    for field in fields:
+        old_value = str(getattr(old, field.name, None))
+        new_value = str(getattr(new, field.name, None))
+
+        if old_value != new_value:
+            diff[field.name] = (old_value, new_value)
+
+    if len(diff) == 0:
+        diff = None
+
+    return diff