server/posts: add ownFavorite field to posts

API.md

@@ -1549,6 +1549,7 @@ One file together with its metadata posted to the site.
     "user":               <user>,
     "score":              <score>,
     "ownScore":           <own-score>,
+    "ownFavorite":        <own-favorite>,
     "tagCount":           <tag-count>,
     "favoriteCount":      <favorite-count>,
     "commentCount":       <comment-count>,
@@ -1612,6 +1613,8 @@ One file together with its metadata posted to the site.
 - `<score>`: the collective score (+1/-1 rating) of the given post.
 - `<own-score>`: the score (+1/-1 rating) of the given post by the
   authenticated user.
+- `<own-favorite>`: whether the authenticated user has given post in their
+  favorites.
 - `<tag-count>`: how many tags the post is tagged with
 - `<favorite-count>`: how many users have the post in their favorites
 - `<comment-count>`: how many comments are filed under that post

server/szurubooru/func/posts.py

@@ -93,6 +93,9 @@ def serialize_post(post, authenticated_user, options=None):
             'user': lambda: users.serialize_micro_user(post.user),
             'score': lambda: post.score,
             'ownScore': lambda: scores.get_score(post, authenticated_user),
+            'ownFavorite': lambda: len(
+                [user for user in post.favorited_by \
+                    if user.user_id == authenticated_user.user_id]) > 0,
             'tagCount': lambda: post.tag_count,
             'favoriteCount': lambda: post.favorite_count,
             'commentCount': lambda: post.comment_count,

server/szurubooru/tests/func/test_posts.py

@@ -147,6 +147,7 @@ def test_serialize_post(
         'notes': [],
         'user': 'post author',
         'score': 1,
+        'ownFavorite': False,
         'ownScore': -1,
         'tagCount': 2,
         'favoriteCount': 1,