queryset-refactor: Moved some backend-specific features into the database

backend code.


git-svn-id: http://code.djangoproject.com/svn/django/branches/queryset-refactor@7087 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/backends/__init__.py

@@ -86,10 +86,9 @@ class BaseDatabaseOperations(object):
         Returns the SQL necessary to cast a datetime value so that it will be
         retrieved as a Python datetime object instead of a string.
 
-        This SQL should include a '%s' in place of the field's name. This
-        method should return None if no casting is necessary.
+        This SQL should include a '%s' in place of the field's name.
         """
-        return None
+        return "%s"
 
     def deferrable_sql(self):
         """
@@ -169,6 +168,14 @@ class BaseDatabaseOperations(object):
             sql += " OFFSET %s" % offset
         return sql
 
+    def lookup_cast(self, lookup_type):
+        """
+        Returns the string to use in a query when performing lookups
+        ("contains", "like", etc). The resulting string should contain a '%s'
+        placeholder for the column being searched against.
+        """
+        return "%s"
+
     def max_name_length(self):
         """
         Returns the maximum length of table and column names, or None if there
@@ -205,6 +212,17 @@ class BaseDatabaseOperations(object):
         """
         return 'RANDOM()'
 
+    def regex_lookup(self, lookup_type):
+        """
+        Returns the string to use in a query when performing regular expression
+        lookups (using "regex" or "iregex"). The resulting string should
+        contain a '%s' placeholder for the column being searched against.
+
+        If the feature is not supported (or part of it is not supported), a
+        NotImplementedError exception can be raised.
+        """
+        raise NotImplementedError
+
     def sql_flush(self, style, tables, sequences):
         """
         Returns a list of SQL statements required to remove all data from

django/db/backends/oracle/base.py

@@ -4,11 +4,12 @@ Oracle database backend for Django.
 Requires cx_Oracle: http://www.python.net/crew/atuining/cx_Oracle/
 """
 
+import datetime
+import os
+
 from django.db.backends import BaseDatabaseWrapper, BaseDatabaseFeatures, BaseDatabaseOperations, util
 from django.utils.datastructures import SortedDict
 from django.utils.encoding import smart_str, force_unicode
-import datetime
-import os
 
 # Oracle takes client-side character set encoding from the environment.
 os.environ['NLS_LANG'] = '.UTF8'
@@ -89,6 +90,11 @@ class DatabaseOperations(BaseDatabaseOperations):
         # Instead, they are handled in django/db/backends/oracle/query.py.
         return ""
 
+    def lookup_cast(self, lookup_type):
+        if lookup_type in ('iexact', 'icontains', 'istartswith', 'iendswith'):
+            return "UPPER(%s)"
+        return "%s"
+
     def max_name_length(self):
         return 30
 
@@ -339,6 +345,16 @@ class DatabaseOperations(BaseDatabaseOperations):
     def random_function_sql(self):
         return "DBMS_RANDOM.RANDOM"
 
+    def regex_lookup_9(self, lookup_type):
+        raise NotImplementedError("Regexes are not supported in Oracle before version 10g.")
+
+    def regex_lookup_10(self, lookup_type):
+        if lookup_type == 'regex':
+            match_option = 'c'
+        else:
+            match_option = 'i'
+        return 'REGEXP_LIKE(%%s %%s %s)' % match_option
+
     def sql_flush(self, style, tables, sequences):
         # Return a list of 'TRUNCATE x;', 'TRUNCATE y;',
         # 'TRUNCATE z;'... style SQL statements
@@ -430,6 +446,14 @@ class DatabaseWrapper(BaseDatabaseWrapper):
                            "NLS_TIMESTAMP_FORMAT = 'YYYY-MM-DD HH24:MI:SS.FF'")
             try:
                 self.oracle_version = int(self.connection.version.split('.')[0])
+                # There's no way for the DatabaseOperations class to know the
+                # currently active Oracle version, so we do some setups here.
+                # TODO: Multi-db support will need a better solution (a way to
+                # communicate the current version).
+                if self.oracle_version <= 9:
+                    self.ops.regex_lookup = self.ops.regex_lookup_9
+                else:
+                    self.ops.regex_lookup = self.ops.regex_lookup_10
             except ValueError:
                 pass
             try:

django/db/models/sql/where.py

@@ -99,19 +99,11 @@ class WhereNode(tree.Node):
         field_sql = connection.ops.field_cast_sql(db_type) % lhs
 
         if isinstance(value, datetime.datetime):
-            # FIXME datetime_cast_sql() should return '%s' by default.
-            cast_sql = connection.ops.datetime_cast_sql() or '%s'
+            cast_sql = connection.ops.datetime_cast_sql()
         else:
             cast_sql = '%s'
 
-        # FIXME: This is out of place. Move to a function like
-        # datetime_cast_sql()
-        if (lookup_type in ('iexact', 'icontains', 'istartswith', 'iendswith')
-                and connection.features.needs_upper_for_iops):
-            format = 'UPPER(%s) %s'
-        else:
-            format = '%s %s'
-
+        format = "%s %%s" % connection.ops.lookup_cast(lookup_type)
         params = field.get_db_prep_lookup(lookup_type, value)
 
         if lookup_type in connection.operators:
@@ -135,18 +127,7 @@ class WhereNode(tree.Node):
         elif lookup_type in 'search':
             return (connection.ops.fulltest_search_sql(field_sql), params)
         elif lookup_type in ('regex', 'iregex'):
-            # FIXME: Factor this out in to connection.ops
-            if settings.DATABASE_ENGINE == 'oracle':
-                if connection.oracle_version and connection.oracle_version <= 9:
-                    raise NotImplementedError("Regexes are not supported in Oracle before version 10g.")
-                if lookup_type == 'regex':
-                    match_option = 'c'
-                else:
-                    match_option = 'i'
-                return ("REGEXP_LIKE(%s, %s, '%s')" % (field_sql, cast_sql,
-                        match_option), params)
-            else:
-                raise NotImplementedError
+            return connection.ops.regex_lookup % (field_sql, cast_sql), params
 
         raise TypeError('Invalid lookup_type: %r' % lookup_type)