bitbake: hashserv: Add database column query API

Adds an API to retrieve the columns that can be queried on from the
database backend. This prevents front end applications from needing to
hardcode the query columns

(Bitbake rev: abfce2b68bdab02ea2e9a63fbb3b9e270428a0a6)

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/hashserv/sqlalchemy.py

@@ -415,3 +415,13 @@ class Database(object):
                 }
 
         return usage
+
+    async def get_query_columns(self):
+        columns = set()
+        for table in (UnihashesV2, OuthashesV2):
+            for c in table.__table__.columns:
+                if not isinstance(c.type, Text):
+                    continue
+                columns.add(c.key)
+
+        return list(columns)