Refactored get_field_cast_sql() to DatabaseOperations.field_cast_sql(). Refs #5106

git-svn-id: http://code.djangoproject.com/svn/django/trunk@5977 bcc190cf-cafb-0310-a4f2-bffc1f526a37

3 files changed, 16 insertions, 11 deletions

diff --git a/django/db/backends/__init__.py b/django/db/backends/__init__.py
index 0a86ed1476..01cc025608 100644
--- a/django/db/backends/__init__.py
+++ b/django/db/backends/__init__.py
@@ -103,6 +103,15 @@ class BaseDatabaseOperations(object):
         """
         return "DROP CONSTRAINT"
 
+    def field_cast_sql(self, db_type):
+        """
+        Given a column type (e.g. 'BLOB', 'VARCHAR'), returns the SQL necessary
+        to cast it before using it in a WHERE statement. Note that the
+        resulting string should contain a '%s' placeholder for the column being
+        searched against.
+        """
+        return '%s'
+
     def fulltext_search_sql(self, field_name):
         """
         Returns the SQL WHERE clause to use in order to perform a full-text
diff --git a/django/db/backends/oracle/base.py b/django/db/backends/oracle/base.py
index 0f1c475871..1a23d36709 100644
--- a/django/db/backends/oracle/base.py
+++ b/django/db/backends/oracle/base.py
@@ -66,6 +66,12 @@ class DatabaseOperations(BaseDatabaseOperations):
     def deferrable_sql(self):
         return " DEFERRABLE INITIALLY DEFERRED"
 
+    def field_cast_sql(self, db_type):
+        if db_type.endswith('LOB'):
+            return "DBMS_LOB.SUBSTR(%s)"
+        else:
+            return "%s"
+
     def last_insert_id(self, cursor, table_name, pk_name):
         sq_name = util.truncate_name(table_name, self.max_name_length() - 3)
         cursor.execute('SELECT %s_sq.currval FROM dual' % sq_name)
@@ -462,12 +468,6 @@ def to_unicode(s):
         return force_unicode(s)
     return s
 
-def get_field_cast_sql(db_type):
-    if db_type.endswith('LOB'):
-        return "DBMS_LOB.SUBSTR(%s%s)"
-    else:
-        return "%s%s"
-
 def get_drop_sequence(table):
     return "DROP SEQUENCE %s;" % DatabaseOperations().quote_name(get_sequence_name(table))
 
diff --git a/django/db/models/query.py b/django/db/models/query.py
index f4ebca2ac5..b0556ac2a3 100644
--- a/django/db/models/query.py
+++ b/django/db/models/query.py
@@ -791,11 +791,7 @@ def get_where_clause(lookup_type, table_prefix, field_name, value, db_type):
         cast_sql = connection.ops.datetime_cast_sql()
     else:
         cast_sql = '%s'
-    if db_type and hasattr(backend, 'get_field_cast_sql'):
-        field_cast_sql = backend.get_field_cast_sql(db_type)
-    else:
-        field_cast_sql = '%s%s'
-    field_sql = field_cast_sql % (table_prefix, field_name)
+    field_sql = connection.ops.field_cast_sql(db_type) % (table_prefix + field_name)
     if lookup_type in ('iexact', 'icontains', 'istartswith', 'iendswith') and connection.features.needs_upper_for_iops:
         format = 'UPPER(%s) %s'
     else: