Render the default value in the way it correctly reflects the type of the original...

This is needed to deal with the case where the coercing isn't supposed to work, as follows:

mysql> CREATE TABLE foo (t1 TIMESTAMP DEFAULT '0');
ERROR 1067 (42000): Invalid default value for 't1'

diff --git a/alembic/ddl/mysql.py b/alembic/ddl/mysql.py
index f5afc22d75d648bdbfaddd10b5972387732fd223..17920b4f6fae4ed55f216b132ed68fa2a7922004 100644 (file)
--- a/alembic/ddl/mysql.py
+++ b/alembic/ddl/mysql.py
@@ -75,14 +75,20 @@ def _mysql_alter_column(element, compiler, **kw):
         ),
     )
 
+def render_value(compiler, expr):
+    if isinstance(expr, basestring):
+        return "'%s'" % expr
+    else:
+        return compiler.sql_compiler.process(expr)
+
 def _mysql_colspec(compiler, name, nullable, server_default, type_):
     spec = "%s %s %s" % (
         name,
         compiler.dialect.type_compiler.process(type_),
         "NULL" if nullable else "NOT NULL"
     )
-    if server_default:
-        spec += " DEFAULT '%s'" % server_default
+    if server_default != False:
+        spec += " DEFAULT %s" % render_value(compiler, server_default)
 
     return spec