From ac12c878edf5a8328bb8ba636b850f92b77f1b7e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?David=20Barrag=C3=A1n=20Merino?=
 <david.barragan@kaleidos.net>
Date: Fri, 5 Sep 2014 12:44:55 +0200
Subject: [PATCH] Fix bug #868: Delete empty description_diff

---
 taiga/projects/history/models.py       | 17 ++++++++++++++++-
 taiga/projects/history/services.py     |  9 ---------
 taiga/projects/notifications/mixins.py |  1 -
 3 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/taiga/projects/history/models.py b/taiga/projects/history/models.py
index ff344b2f..cbbb5085 100644
--- a/taiga/projects/history/models.py
+++ b/taiga/projects/history/models.py
@@ -21,6 +21,8 @@ from django.db.models.loading import get_model
 from django.utils.functional import cached_property
 from django_pgjson.fields import JsonField
 
+from taiga.mdrender.service import get_diff_of_htmls
+
 from .choices import HistoryType
 from .choices import HISTORY_TYPE_CHOICES
 
@@ -82,7 +84,20 @@ class HistoryEntry(models.Model):
         for key in self.diff:
             value = None
 
-            if key in users_keys:
+            # Note: Hack to prevent description_diff propagation
+            #       on old HistoryEntry objects.
+            if key == "description_diff":
+                continue
+            elif key == "description":
+                description_diff = get_diff_of_htmls(
+                    self.diff[key][0],
+                    self.diff[key][1]
+                )
+
+                if description_diff:
+                    key = "description_diff"
+                    value = (None, description_diff)
+            elif key in users_keys:
                 value = [resolve_value("users", x) for x in self.diff[key]]
             elif key == "watchers":
                 value = [[resolve_value("users", x) for x in self.diff[key][0]],
diff --git a/taiga/projects/history/services.py b/taiga/projects/history/services.py
index 775604d4..e04068ed 100644
--- a/taiga/projects/history/services.py
+++ b/taiga/projects/history/services.py
@@ -39,7 +39,6 @@ from django.db.models.loading import get_model
 from django.db import transaction as tx
 
 from taiga.mdrender.service import render as mdrender
-from taiga.mdrender.service import get_diff_of_htmls
 from taiga.base.utils.db import get_typename_for_model_class
 
 from .models import HistoryType
@@ -161,14 +160,6 @@ def make_diff(oldobj:FrozenObj, newobj:FrozenObj) -> FrozenDiff:
         if key not in first:
             diff[key] = (not_found_value, second[key])
 
-    if "description" in diff:
-        description_diff = get_diff_of_htmls(
-            diff["description"][0],
-            diff["description"][1]
-        )
-        if description_diff:
-            diff["description_diff"] = (not_found_value, description_diff)
-
     return FrozenDiff(newobj.key, diff, newobj.snapshot)
 
 
diff --git a/taiga/projects/notifications/mixins.py b/taiga/projects/notifications/mixins.py
index e0a796ef..2db9007f 100644
--- a/taiga/projects/notifications/mixins.py
+++ b/taiga/projects/notifications/mixins.py
@@ -43,7 +43,6 @@ class WatchedResourceMixin(object):
         cases on actions methods that not uses standard
         `post_save` hook of drf resources.
         """
-
         if history is None:
             history = self.get_last_history()