cant' change mysql schematype due to DROP constraint

[sqlalchemy-bot]

Migrated issue, originally created by Michael Bayer (@zzzeek)

diff --git a/tests/test_mysql.py b/tests/test_mysql.py
index 2dc8838..7600ebf 100644
--- a/tests/test_mysql.py
+++ b/tests/test_mysql.py
@@ -1,4 +1,4 @@
-from sqlalchemy import Integer, func
+from sqlalchemy import Integer, func, Boolean
 from alembic.testing.fixtures import TestBase
 from alembic.testing import config
 from sqlalchemy import TIMESTAMP, MetaData, Table, Column, text
@@ -102,6 +102,17 @@ class MySQLOpTest(TestBase):
             'ALTER TABLE t ALTER COLUMN c DROP DEFAULT'
         )
 
+    def test_alter_column_remove_schematype(self):
+        context = op_fixture('mysql')
+        op.alter_column(
+            "t", "c",
+            type_=Integer,
+            existing_type=Boolean(create_constraint=True, name="ck1"),
+            server_default=None)
+        context.assert_(
+            'ALTER TABLE t MODIFY c INTEGER NULL'
+        )
+
     def test_alter_column_modify_default(self):
         context = op_fixture('mysql')
         # notice we dont need the existing type on this one...

stack:

#!


Traceback (most recent call last):
  File "/home/classic/dev/alembic/tests/test_mysql.py", line 111, in test_alter_column_remove_schematype
    server_default=None)
  File "<string>", line 8, in alter_column
  File "<string>", line 3, in alter_column
  File "/home/classic/dev/alembic/alembic/operations/ops.py", line 1414, in alter_column
    return operations.invoke(alt)
  File "/home/classic/dev/alembic/alembic/operations/base.py", line 318, in invoke
    return fn(self, operation)
  File "/home/classic/dev/alembic/alembic/operations/toimpl.py", line 41, in alter_column
    operations.impl.drop_constraint(constraint)
  File "/home/classic/dev/alembic/alembic/ddl/impl.py", line 183, in drop_constraint
    self._exec(schema.DropConstraint(const))
  File "/home/classic/dev/alembic/alembic/ddl/impl.py", line 118, in _exec
    return conn.execute(construct, *multiparams, **params)
  File "/home/classic/dev/alembic/alembic/testing/fixtures.py", line 151, in execute
    sql = text_type(stmt.compile(dialect=ctx_dialect))
  File "<string>", line 1, in <lambda>
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/sql/elements.py", line 433, in compile
    return self._compiler(dialect, bind=bind, **kw)
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/sql/ddl.py", line 26, in _compiler
    return dialect.ddl_compiler(dialect, self, **kw)
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/sql/compiler.py", line 206, in __init__
    self.string = self.process(self.statement, **compile_kwargs)
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/sql/compiler.py", line 229, in process
    return obj._compiler_dispatch(self, **kwargs)
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/ext/compiler.py", line 423, in <lambda>
    lambda *arg, **kw: existing(*arg, **kw))
  File "/home/classic/dev/sqlalchemy/lib/sqlalchemy/ext/compiler.py", line 461, in __call__
    return fn(element, compiler, **kw)
  File "/home/classic/dev/alembic/alembic/ddl/mysql.py", line 312, in _mysql_drop_constraint
    "MySQL does not support CHECK constraints.")
NotImplementedError: MySQL does not support CHECK constraints.

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

• Repaired batch migration support for "schema" types which generate
  constraints, in particular the Boolean datatype which generates
  a CHECK constraint. Previously, an alter column operation with this
  type would fail to correctly accommodate for the CHECK constraint
  on change both from and to this type. In the former case the operation
  would fail entirely, in the latter, the CHECK constraint would
  not get generated. Both of these issues are repaired.
  fixes #354
• Changing a schema type such as Boolean to a non-schema type would
  emit a drop constraint operation which emits NotImplementedError for
  the MySQL dialect. This drop constraint operation is now skipped when
  the constraint originates from a schema type.
  fixes #355

→ 9eb7f32

[sqlalchemy-bot]

Changes by Michael Bayer (@zzzeek):

• changed status to closed

[sqlalchemy-bot]

Martin Domke (@mdomke) wrote:

Is there any time schedule when this fix does make it into a release?

[sqlalchemy-bot]

Michael Bayer (@zzzeek) wrote:

it's released.