diff --git a/django/db/migrations/operations/__init__.py b/django/db/migrations/operations/__init__.py
index 6c2c784635..925b05fff3 100644
--- a/django/db/migrations/operations/__init__.py
+++ b/django/db/migrations/operations/__init__.py
@@ -1,2 +1,2 @@
from .models import CreateModel, DeleteModel, AlterModelTable
-from .fields import AddField, RemoveField
+from .fields import AddField, RemoveField, AlterField, RenameField
diff --git a/django/db/migrations/operations/fields.py b/django/db/migrations/operations/fields.py
index 660cba6b72..cc4f4a43df 100644
--- a/django/db/migrations/operations/fields.py
+++ b/django/db/migrations/operations/fields.py
@@ -54,3 +54,71 @@ class RemoveField(Operation):
def describe(self):
return "Remove field %s from %s" % (self.name, self.model_name)
+
+
+class AlterField(Operation):
+ """
+ Alters a field's database column (e.g. null, max_length) to the provided new field
+ """
+
+ def __init__(self, model_name, name, field):
+ self.model_name = model_name
+ self.name = name
+ self.field = field
+
+ def state_forwards(self, app_label, state):
+ state.models[app_label, self.model_name.lower()].fields = [
+ (n, self.field if n == self.name else f) for n, f in state.models[app_label, self.model_name.lower()].fields
+ ]
+
+ def database_forwards(self, app_label, schema_editor, from_state, to_state):
+ from_model = from_state.render().get_model(app_label, self.model_name)
+ to_model = to_state.render().get_model(app_label, self.model_name)
+ schema_editor.alter_field(
+ from_model,
+ from_model._meta.get_field_by_name(self.name)[0],
+ to_model._meta.get_field_by_name(self.name)[0],
+ )
+
+ def database_backwards(self, app_label, schema_editor, from_state, to_state):
+ self.database_forwards(app_label, schema_editor, from_state, to_state)
+
+ def describe(self):
+ return "Alter field %s on %s" % (self.name, self.model_name)
+
+
+class RenameField(Operation):
+ """
+ Renames a field on the model. Might affect db_column too.
+ """
+
+ def __init__(self, model_name, old_name, new_name):
+ self.model_name = model_name
+ self.old_name = old_name
+ self.new_name = new_name
+
+ def state_forwards(self, app_label, state):
+ state.models[app_label, self.model_name.lower()].fields = [
+ (self.new_name if n == self.old_name else n, f) for n, f in state.models[app_label, self.model_name.lower()].fields
+ ]
+
+ def database_forwards(self, app_label, schema_editor, from_state, to_state):
+ from_model = from_state.render().get_model(app_label, self.model_name)
+ to_model = to_state.render().get_model(app_label, self.model_name)
+ schema_editor.alter_field(
+ from_model,
+ from_model._meta.get_field_by_name(self.old_name)[0],
+ to_model._meta.get_field_by_name(self.new_name)[0],
+ )
+
+ def database_backwards(self, app_label, schema_editor, from_state, to_state):
+ from_model = from_state.render().get_model(app_label, self.model_name)
+ to_model = to_state.render().get_model(app_label, self.model_name)
+ schema_editor.alter_field(
+ from_model,
+ from_model._meta.get_field_by_name(self.new_name)[0],
+ to_model._meta.get_field_by_name(self.old_name)[0],
+ )
+
+ def describe(self):
+ return "Rename field %s on %s to %s" % (self.old_name, self.model_name, self.new_name)
diff --git a/django/db/migrations/state.py b/django/db/migrations/state.py
index b6618041f2..65b749c80c 100644
--- a/django/db/migrations/state.py
+++ b/django/db/migrations/state.py
@@ -93,10 +93,17 @@ class ModelState(object):
def clone(self):
"Returns an exact copy of this ModelState"
+ # We deep-clone the fields using deconstruction
+ fields = []
+ for name, field in self.fields:
+ _, path, args, kwargs = field.deconstruct()
+ field_class = import_by_path(path)
+ fields.append((name, field_class(*args, **kwargs)))
+ # Now make a copy
return self.__class__(
app_label = self.app_label,
name = self.name,
- fields = list(self.fields),
+ fields = fields,
options = dict(self.options),
bases = self.bases,
)
diff --git a/tests/migrations/test_operations.py b/tests/migrations/test_operations.py
index 50674e84ba..6ee60afa5b 100644
--- a/tests/migrations/test_operations.py
+++ b/tests/migrations/test_operations.py
@@ -22,6 +22,12 @@ class OperationTests(TestCase):
def assertColumnNotExists(self, table, column):
self.assertNotIn(column, [c.name for c in connection.introspection.get_table_description(connection.cursor(), table)])
+ def assertColumnNull(self, table, column):
+ self.assertEqual([c.null_ok for c in connection.introspection.get_table_description(connection.cursor(), table) if c.name == column][0], True)
+
+ def assertColumnNotNull(self, table, column):
+ self.assertEqual([c.null_ok for c in connection.introspection.get_table_description(connection.cursor(), table) if c.name == column][0], False)
+
def set_up_test_model(self, app_label):
"""
Creates a test model state and database table.
@@ -50,7 +56,7 @@ class OperationTests(TestCase):
"Pony",
[
("id", models.AutoField(primary_key=True)),
- ("pink", models.BooleanField(default=True)),
+ ("pink", models.IntegerField(default=1)),
],
)
# Test the state alteration
@@ -157,3 +163,48 @@ class OperationTests(TestCase):
operation.database_backwards("test_almota", editor, new_state, project_state)
self.assertTableExists("test_almota_pony")
self.assertTableNotExists("test_almota_pony_2")
+
+ def test_alter_field(self):
+ """
+ Tests the AlterField operation.
+ """
+ project_state = self.set_up_test_model("test_alfl")
+ # Test the state alteration
+ operation = migrations.AlterField("Pony", "pink", models.IntegerField(null=True))
+ new_state = project_state.clone()
+ operation.state_forwards("test_alfl", new_state)
+ self.assertEqual([f for n, f in project_state.models["test_alfl", "pony"].fields if n == "pink"][0].null, False)
+ self.assertEqual([f for n, f in new_state.models["test_alfl", "pony"].fields if n == "pink"][0].null, True)
+ # Test the database alteration
+ self.assertColumnNotNull("test_alfl_pony", "pink")
+ with connection.schema_editor() as editor:
+ operation.database_forwards("test_alfl", editor, project_state, new_state)
+ self.assertColumnNull("test_alfl_pony", "pink")
+ # And test reversal
+ with connection.schema_editor() as editor:
+ operation.database_backwards("test_alfl", editor, new_state, project_state)
+ self.assertColumnNotNull("test_alfl_pony", "pink")
+
+ def test_rename_field(self):
+ """
+ Tests the RenameField operation.
+ """
+ project_state = self.set_up_test_model("test_rnfl")
+ # Test the state alteration
+ operation = migrations.RenameField("Pony", "pink", "blue")
+ new_state = project_state.clone()
+ operation.state_forwards("test_rnfl", new_state)
+ self.assertIn("blue", [n for n, f in new_state.models["test_rnfl", "pony"].fields])
+ self.assertNotIn("pink", [n for n, f in new_state.models["test_rnfl", "pony"].fields])
+ # Test the database alteration
+ self.assertColumnExists("test_rnfl_pony", "pink")
+ self.assertColumnNotExists("test_rnfl_pony", "blue")
+ with connection.schema_editor() as editor:
+ operation.database_forwards("test_rnfl", editor, project_state, new_state)
+ self.assertColumnExists("test_rnfl_pony", "blue")
+ self.assertColumnNotExists("test_rnfl_pony", "pink")
+ # And test reversal
+ with connection.schema_editor() as editor:
+ operation.database_backwards("test_rnfl", editor, new_state, project_state)
+ self.assertColumnExists("test_rnfl_pony", "pink")
+ self.assertColumnNotExists("test_rnfl_pony", "blue")