Modifications to allow the backends to control the behavior of an empty insert. If supports_empty_insert is True then the backend specifically supports the 'insert into t1 () values ()' syntax. If supports_default_values is True then the backend supports the 'insert into t1 default values' syntax. If both are false then the backend has no support for empty inserts at all and an exception gets raised. Changes here are careful to not change current behavior except where the current behavior was failing to begin with.

6 files changed, 36 insertions, 25 deletions

diff --git a/lib/sqlalchemy/databases/mssql.py b/lib/sqlalchemy/databases/mssql.py
index 1ff482cf5..4bbc2caf7 100644
--- a/lib/sqlalchemy/databases/mssql.py
+++ b/lib/sqlalchemy/databases/mssql.py
@@ -361,6 +361,8 @@ class MSSQLExecutionContext_pyodbc (MSSQLExecutionContext):
 
 class MSSQLDialect(default.DefaultDialect):
     name = 'mssql'
+    supports_default_values = True
+    supports_empty_insert = False
 
     colspecs = {
         sqltypes.Unicode : MSNVarchar,
diff --git a/lib/sqlalchemy/databases/postgres.py b/lib/sqlalchemy/databases/postgres.py
index 1c410af53..c8abeb6db 100644
--- a/lib/sqlalchemy/databases/postgres.py
+++ b/lib/sqlalchemy/databases/postgres.py
@@ -302,6 +302,8 @@ class PGDialect(default.DefaultDialect):
     preexecute_pk_sequences = True
     supports_pk_autoincrement = False
     default_paramstyle = 'pyformat'
+    supports_default_values = True
+    supports_empty_insert = False
 
     def __init__(self, server_side_cursors=False, **kwargs):
         default.DefaultDialect.__init__(self, **kwargs)
diff --git a/lib/sqlalchemy/databases/sqlite.py b/lib/sqlalchemy/databases/sqlite.py
index 70c3f74ec..b3de98100 100644
--- a/lib/sqlalchemy/databases/sqlite.py
+++ b/lib/sqlalchemy/databases/sqlite.py
@@ -242,6 +242,8 @@ class SQLiteDialect(default.DefaultDialect):
     supports_alter = False
     supports_unicode_statements = True
     default_paramstyle = 'qmark'
+    supports_default_values = True
+    supports_empty_insert = False
 
     def __init__(self, **kwargs):
         default.DefaultDialect.__init__(self, **kwargs)
@@ -465,25 +467,6 @@ class SQLiteCompiler(compiler.DefaultCompiler):
         # sqlite has no "FOR UPDATE" AFAICT
         return ''
 
-    def visit_insert(self, insert_stmt):
-        self.isinsert = True
-        colparams = self._get_colparams(insert_stmt)
-        preparer = self.preparer
-
-        if not colparams:
-            if not self.dialect.supports_default_values:
-                raise exc.NotSupportedError(
-                    "The version of SQLite you are using, %s, does not support DEFAULT VALUES." % (self.dialect.dbapi.sqlite_version))
-
-            return ("INSERT INTO %s DEFAULT VALUES" % (
-                (preparer.format_table(insert_stmt.table),)))
-        else:
-            return ("INSERT INTO %s (%s) VALUES (%s)" %
-                    (preparer.format_table(insert_stmt.table),
-                     ', '.join([preparer.format_column(c[0])
-                                for c in colparams]),
-                     ', '.join([c[1] for c in colparams])))
-
 
 class SQLiteSchemaGenerator(compiler.SchemaGenerator):
 
diff --git a/lib/sqlalchemy/engine/default.py b/lib/sqlalchemy/engine/default.py
index a90142702..96dadd045 100644
--- a/lib/sqlalchemy/engine/default.py
+++ b/lib/sqlalchemy/engine/default.py
@@ -39,7 +39,8 @@ class DefaultDialect(base.Dialect):
     supports_pk_autoincrement = True
     dbapi_type_map = {}
     default_paramstyle = 'named'
-    supports_default_values = True
+    supports_default_values = False 
+    supports_empty_insert = True
 
     def __init__(self, convert_unicode=False, assert_unicode=False, encoding='utf-8', paramstyle=None, dbapi=None, **kwargs):
         self.convert_unicode = convert_unicode
diff --git a/lib/sqlalchemy/sql/compiler.py b/lib/sqlalchemy/sql/compiler.py
index 0117b96ff..2072d5a27 100644
--- a/lib/sqlalchemy/sql/compiler.py
+++ b/lib/sqlalchemy/sql/compiler.py
@@ -570,11 +570,18 @@ class DefaultCompiler(engine.Compiled):
         insert = ' '.join(["INSERT"] +
                           [self.process(x) for x in insert_stmt._prefixes])
 
-        return (insert + " INTO %s (%s) VALUES (%s)" %
+        if not colparams and not self.dialect.supports_default_values and not self.dialect.supports_empty_insert:
+            raise exc.NotSupportedError(
+                "The version of %s you are using does not support empty inserts." % self.dialect.name)
+        elif not colparams and self.dialect.supports_default_values:
+            return (insert + " INTO %s DEFAULT VALUES" % (
+                (preparer.format_table(insert_stmt.table),)))
+        else: 
+            return (insert + " INTO %s (%s) VALUES (%s)" %
                 (preparer.format_table(insert_stmt.table),
-                 ', '.join(preparer.quote(c[0].name, c[0].quote)
-                           for c in colparams),
-                 ', '.join(c[1] for c in colparams)))
+                 ', '.join([preparer.format_column(c[0])
+                           for c in colparams]),
+                 ', '.join([c[1] for c in colparams])))
 
     def visit_update(self, update_stmt):
         self.stack.append({'from': set([update_stmt.table])})
diff --git a/test/sql/defaults.py b/test/sql/defaults.py
index 4f0f929f1..169d60c67 100644
--- a/test/sql/defaults.py
+++ b/test/sql/defaults.py
@@ -1,8 +1,9 @@
 import testenv; testenv.configure_for_tests()
 import datetime
 from sqlalchemy import Sequence, Column, func
+from sqlalchemy.sql import select, text
 from testlib import sa, testing
-from testlib.sa import MetaData, Table, Integer, String, ForeignKey
+from testlib.sa import MetaData, Table, Integer, String, ForeignKey, Boolean
 from testlib.testing import eq_
 from sql import _base
 
@@ -472,6 +473,21 @@ class PKIncrementTest(_base.TablesTest):
             con.close()
 
 
+class EmptyInsertTest(testing.TestBase):
+    @testing.exclude('sqlite', '<', (3, 3, 8), 'no empty insert support')
+    def test_empty_insert(self):
+        metadata = MetaData(testing.db)
+        t1 = Table('t1', metadata,
+                Column('is_true', Boolean, server_default=('1')))
+        metadata.create_all()
+        
+        try:
+            result = t1.insert().execute()
+            self.assertEquals(1, select([func.count(text('*'))], from_obj=t1).scalar())
+            self.assertEquals(True, t1.select().scalar())
+        finally:
+            metadata.drop_all()
+
 class AutoIncrementTest(_base.TablesTest):
     __requires__ = ('identity',)
     run_define_tables = 'each'