[ESN-1439] Fix sqlfilter (OpenGov-OpenData#2)

* Keep double quotes in sqlfilter. Double quotes are used for DB identifiers like column name

* Catch ValidationError and return error message

ckanext/odata/actions.py

@@ -96,11 +96,9 @@ def odata(context, data_dict):
     # as they should be specified by the sql query
     if t.request.GET.get('$sqlfilter'):
         action = t.get_action('datastore_search_sql')
-
-        # Replace double quotes with single quotes to avoid syntax errors.
-        # Not sure if this will cause us any trouble later.
-        query = t.request.GET.get('$sqlfilter').replace('"','\'')
-        sql = "SELECT * FROM \"%s\" %s"%(resource_id,query)
+
+        query = t.request.GET.get('$sqlfilter')
+        sql = "SELECT * FROM \"%s\" %s"%(resource_id, query)
 
         data_dict = {
             'sql': sql
@@ -118,14 +116,14 @@ def odata(context, data_dict):
             'offset': offset
         }
 
-
     try:
         result = action({}, data_dict)
     except t.ObjectNotFound:
         t.abort(404, t._('DataStore resource not found'))
     except t.NotAuthorized:
         t.abort(401, t._('DataStore resource not authourized'))
-
+    except t.ValidationError as e:
+        return json.dumps(e.error_dict)
 
     if not t.request.GET.get('$sqlfilter'):
         num_results = result['total']