Update recommend endpoint and validation.

get_recommendations was recently changed to accept id36s instead of subreddit
objects for the omit list. This change updates the recommender api endpoint
to match. It also makes the VSRByNames() validator return an empty dict in
case of error so it's safe to call .values() on the result.

Note: Fixes the broken "more suggestions" link in multi recommendations.

r2/r2/controllers/api.py

@@ -3694,8 +3694,9 @@ class ApiController(RedditController, OAuth2ResourceController):
         that appear in the optional `omit` param.
 
         """
+        omit_id36s = [sr._id36 for sr in to_omit.values()]
         rec_srs = recommender.get_recommendations(srs.values(),
-                                                  to_omit=to_omit.values())
+                                                  to_omit=omit_id36s)
         sr_data = [{'sr_name': sr.name} for sr in rec_srs]
         return json.dumps(sr_data)
 

r2/r2/lib/recommender.py

@@ -63,7 +63,7 @@ def get_recommendations(srs,
     - srs is one Subreddit object or a list of Subreddits
     - count is total number of results to return
     - source is a prefix telling which set of recommendations to use
-    - to_omit is one Subreddit object or a list of Subreddits that should not
+    - to_omit is a single or list of subreddit id36s that should not be
         be included. (Useful for omitting recs that were already rejected.)
     - match_set=True will return recs that are similar to each other, useful
         for matching the "theme" of the original set

r2/r2/lib/validator/validator.py

@@ -718,9 +718,7 @@ class VSRByNames(Validator):
             return Subreddit._by_name(sr_names)
         elif self.required:
             self.set_error(errors.BAD_SR_NAME, code=400)
-            return
-        else:
-            return {}
+        return {}
 
     def param_docs(self):
         return {