Preprocess the where clauses. (#2405)

superset/connectors/sqla/models.py

@@ -517,6 +517,7 @@ def visit_column(element, compiler, **kw):
         )
         logging.info(sql)
         sql = sqlparse.format(sql, reindent=True)
+        sql = self.database.db_engine_spec.sql_preprocessor(sql)
         return sql
 
     def query(self, query_obj):

superset/db_engine_specs.py

@@ -115,9 +115,9 @@ def extract_error_message(cls, e):
     def sql_preprocessor(cls, sql):
         """If the SQL needs to be altered prior to running it
 
-        For example Presto needs to double `%` characters
+        For example db api needs to double `%` characters
         """
-        return sql
+        return sql.replace('%', '%%')
 
     @classmethod
     def patch(cls):
@@ -279,10 +279,6 @@ def patch(cls):
         from superset.db_engines import presto as patched_presto
         presto.Cursor.cancel = patched_presto.cancel
 
-    @classmethod
-    def sql_preprocessor(cls, sql):
-        return sql.replace('%', '%%')
-
     @classmethod
     def convert_dttm(cls, target_type, dttm):
         tt = target_type.upper()