adding delete

Author: antgonza

qiita_db/study.py

@@ -984,16 +984,22 @@ def tags(self, tag_ids):
             The tag ids of the study
         """
         with qdb.sql_connection.TRN:
-            sql = """INSERT INTO qiita.per_study_tags (study_tag_id, study_id)
-                     SELECT %s, %s
-                        WHERE
-                            NOT EXISTS (
-                                SELECT study_tag_id, study_id
-                                FROM qiita.per_study_tags
-                                WHERE study_tag_id = %s AND study_id = %s
-                            )"""
-            sql_args = [[tid, self._id, tid, self._id] for tid in tag_ids]
-            qdb.sql_connection.TRN.add(sql, sql_args, many=True)
+            sql = """DELETE FROM qiita.per_study_tags WHERE study_id = %s"""
+            qdb.sql_connection.TRN.add(sql, [self._id])
+            qdb.sql_connection.TRN.execute()
+
+            if tag_ids:
+                sql = """INSERT INTO qiita.per_study_tags
+                            (study_tag_id, study_id)
+                         SELECT %s, %s
+                            WHERE
+                                NOT EXISTS (
+                                    SELECT study_tag_id, study_id
+                                    FROM qiita.per_study_tags
+                                    WHERE study_tag_id = %s AND study_id = %s
+                                )"""
+                sql_args = [[tid, self._id, tid, self._id] for tid in tag_ids]
+                qdb.sql_connection.TRN.add(sql, sql_args, many=True)
             return qdb.sql_connection.TRN.execute()
 
 # --- methods ---

qiita_db/test/test_study.py

@@ -847,7 +847,16 @@ def test_study_tags(self):
         study = qdb.study.Study(1)
         study.tags = [tig for tig, tag in obs]
         # and checking that everything went fine
-        self.assertEqual(exp, study.tags)
+        self.assertEqual(obs, study.tags)
+
+        # making sure that everything is overwritten
+        obs.pop()
+        study.tags = [tig for tig, tag in obs]
+        self.assertEqual(obs, study.tags)
+
+        # cleaning tags
+        study.tags = []
+        self.assertEqual(study.tags, [])
 
 
 if __name__ == "__main__":