extract() is now dialect-sensitive and supports SQLite and others.

1 files changed, 22 insertions, 0 deletions

diff --git a/lib/sqlalchemy/databases/sqlite.py b/lib/sqlalchemy/databases/sqlite.py
index 77eb30ff8..b77a315b8 100644
--- a/lib/sqlalchemy/databases/sqlite.py
+++ b/lib/sqlalchemy/databases/sqlite.py
@@ -557,12 +557,34 @@ class SQLiteCompiler(compiler.DefaultCompiler):
         }
     )
 
+    extract_map = compiler.DefaultCompiler.extract_map.copy()
+    extract_map.update({
+        'month': '%m',
+        'day': '%d',
+        'year': '%Y',
+        'second': '%S',
+        'hour': '%H',
+        'doy': '%j',
+        'minute': '%M',
+        'epoch': '%s',
+        'dow': '%w',
+        'week': '%W'
+    })
+
     def visit_cast(self, cast, **kwargs):
         if self.dialect.supports_cast:
             return super(SQLiteCompiler, self).visit_cast(cast)
         else:
             return self.process(cast.clause)
 
+    def visit_extract(self, extract):
+        try:
+            return "CAST(STRFTIME('%s', %s) AS INTEGER)" % (
+                self.extract_map[extract.field], self.process(extract.expr))
+        except KeyError:
+            raise exc.ArgumentError(
+                "%s is not a valid extract argument." % extract.field)
+
     def limit_clause(self, select):
         text = ""
         if select._limit is not None: