added drop primary key constraint

2 files changed, 9 insertions, 1 deletions

diff --git a/alembic/operations.py b/alembic/operations.py
index 4297a25..1d59df3 100644
--- a/alembic/operations.py
+++ b/alembic/operations.py
@@ -565,13 +565,14 @@ class Operations(object):
         :param name: name of the constraint.
         :param tablename: tablename.
         :param type: optional, required on MySQL.  can be 
-        'foreignkey', 'unique', or 'check'
+        'foreignkey', 'primary', 'unique', or 'check'
 
         """
         t = self._table(tablename)
         types = {
             'foreignkey':lambda name:schema.ForeignKeyConstraint(
                                 [], [], name=name),
+            'primary':schema.PrimaryKeyConstraint,        
             'unique':schema.UniqueConstraint,
             'check':lambda name:schema.CheckConstraint("", name=name),
             None:schema.Constraint
diff --git a/tests/test_mysql.py b/tests/test_mysql.py
index 4c4a357..548217e 100644
--- a/tests/test_mysql.py
+++ b/tests/test_mysql.py
@@ -48,6 +48,13 @@ def test_drop_fk():
         "ALTER TABLE t1 DROP FOREIGN KEY f1"
     )
 
+def test_drop_constraint_primary():
+    context = op_fixture('mysql')
+    op.drop_constraint('primary', 't1',type='primary')
+    context.assert_(
+        "ALTER TABLE t1 DROP PRIMARY KEY "
+    )
+
 def test_drop_unique():
     context = op_fixture('mysql')
     op.drop_constraint("f1", "t1", "unique")