From 13a3eff340583648dadf62cdbfd0220a3b8f48d2 Mon Sep 17 00:00:00 2001
From: Deimos <deimos@tildes.net>
Date: Thu, 19 Jul 2018 18:50:32 -0600
Subject: [PATCH] Prevent adding a TopicLog entry if tags unchanged

Previously, an entry would be added to the topic log even if someone
didn't actually change the topic's tags at all. This commit fixes that,
as well as moving the the template fragment that renders the list into a
separate file in includes/ that can be used both for the initial render
as well as by intercooler when it updates that section of the page.
---
 .../templates/includes/topic_tags.jinja2      |  9 +++++++
 .../templates/intercooler/topic_tags.jinja2   |  6 +----
 tildes/tildes/templates/topic.jinja2          | 10 +------
 tildes/tildes/views/api/web/topic.py          | 27 ++++++++-----------
 4 files changed, 22 insertions(+), 30 deletions(-)
 create mode 100644 tildes/tildes/templates/includes/topic_tags.jinja2

diff --git a/tildes/tildes/templates/includes/topic_tags.jinja2 b/tildes/tildes/templates/includes/topic_tags.jinja2
new file mode 100644
index 0000000..55b3472
--- /dev/null
+++ b/tildes/tildes/templates/includes/topic_tags.jinja2
@@ -0,0 +1,9 @@
+<ul class="topic-tags">
+  {% for tag in topic.tags %}
+    <li class="label label-topic-tag">
+      <a href="/~{{ topic.group.path }}?tag={{ tag.replace(' ', '_') }}">{{ tag }}</a>
+    </li>
+  {% else %}
+    <li class="label label-topic-tag">No tags</li>
+  {% endfor %}
+</ul>
diff --git a/tildes/tildes/templates/intercooler/topic_tags.jinja2 b/tildes/tildes/templates/intercooler/topic_tags.jinja2
index 292d8be..58ba1df 100644
--- a/tildes/tildes/templates/intercooler/topic_tags.jinja2
+++ b/tildes/tildes/templates/intercooler/topic_tags.jinja2
@@ -1,5 +1 @@
-<ul class="topic-tags">
-  {% for tag in topic.tags %}
-    <li class="label label-topic-tag">{{ tag }}</li>
-  {% endfor %}
-</ul>
+{% include 'includes/topic_tags.jinja2' %}
diff --git a/tildes/tildes/templates/topic.jinja2 b/tildes/tildes/templates/topic.jinja2
index 15b7a20..6859134 100644
--- a/tildes/tildes/templates/topic.jinja2
+++ b/tildes/tildes/templates/topic.jinja2
@@ -204,15 +204,7 @@
 <dl>
   <dt>Tags</dt>
   <dd>
-    <ul class="topic-tags">
-      {% for tag in topic.tags %}
-        <li class="label label-topic-tag">
-          <a href="/~{{ topic.group.path }}?tag={{ tag.replace(' ', '_') }}">{{ tag }}</a>
-        </li>
-      {% else %}
-        <li class="label label-topic-tag">No tags</li>
-      {% endfor %}
-    </ul>
+    {% include 'includes/topic_tags.jinja2' %}
   </dd>
 
   <dt>Comments</dt>
diff --git a/tildes/tildes/views/api/web/topic.py b/tildes/tildes/views/api/web/topic.py
index b97d565..6e33b66 100644
--- a/tildes/tildes/views/api/web/topic.py
+++ b/tildes/tildes/views/api/web/topic.py
@@ -14,7 +14,7 @@ from tildes.models.log import LogTopic
 from tildes.models.topic import Topic, TopicVote
 from tildes.schemas.group import GroupSchema
 from tildes.schemas.topic import TopicSchema
-from tildes.views import IC_EMPTY, IC_NOOP
+from tildes.views import IC_NOOP
 from tildes.views.decorators import ic_view_config
 
 
@@ -160,28 +160,23 @@ def tag_topic(request: Request, tags: str) -> dict:
     """Apply tags to a topic with Intercooler."""
     topic = request.context
 
-    if not tags:
-        request.db_session.add(
-            LogTopic(
-                LogEventType.TOPIC_TAG,
-                request,
-                topic,
-                info={'old': topic.tags, 'new': []},
-            ),
-        )
-        topic.tags = []
-        return IC_EMPTY
-
-    # split the tag string on commas
-    split_tags = tags.split(',')
+    if tags:
+        # split the tag string on commas
+        new_tags = tags.split(',')
+    else:
+        new_tags = []
 
     old_tags = topic.tags
 
     try:
-        topic.tags = split_tags
+        topic.tags = new_tags
     except ValidationError:
         raise ValidationError({'tags': ['Invalid tags']})
 
+    # if tags weren't changed, don't add a log entry or update page
+    if set(topic.tags) == set(old_tags):
+        return IC_NOOP
+
     request.db_session.add(
         LogTopic(
             LogEventType.TOPIC_TAG,