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Migration ability to move models between apps #11920

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150c4c4
update MigrationAutodetector, RenameModel-operation to handle moving …
wtayyeb Oct 16, 2019
fb99318
Update django/db/migrations/operations/models.py to use super()
wtayyeb Oct 24, 2019
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21 changes: 19 additions & 2 deletions django/db/migrations/autodetector.py
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Original file line number Diff line number Diff line change
Expand Up @@ -477,7 +477,8 @@ def generate_renamed_models(self):

removed_models = self.old_model_keys - self.new_model_keys
for rem_app_label, rem_model_name in removed_models:
if rem_app_label == app_label:
is_moving = not bool(rem_app_label == app_label)
if True or rem_app_label == app_label: # TODO remove if and reduce indent
rem_model_state = self.from_state.models[rem_app_label, rem_model_name]
rem_model_fields_def = self.only_relation_agnostic_fields(rem_model_state.fields)
if model_fields_def == rem_model_fields_def:
Expand All @@ -487,11 +488,27 @@ def generate_renamed_models(self):
for field in model_opts.get_fields():
if field.is_relation:
dependencies.extend(self._get_dependencies_for_foreign_key(field))
if is_moving:
self.add_operation(
app_label,
operations.MoveModelPlaceholder(
old_name=rem_model_state.name,
new_name=model_state.name,
new_app_label=app_label if is_moving else None,
),
dependencies=[
(rem_app_label, rem_model_name, None, True),
],
)
self.from_state.add_model(model_state)
dependencies.append((app_label, model_name, None, True))

self.add_operation(
app_label,
rem_app_label,
operations.RenameModel(
old_name=rem_model_state.name,
new_name=model_state.name,
new_app_label=app_label if is_moving else None,
),
dependencies=dependencies,
)
Expand Down
72 changes: 64 additions & 8 deletions django/db/migrations/operations/models.py
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Original file line number Diff line number Diff line change
Expand Up @@ -275,11 +275,12 @@ def describe(self):


class RenameModel(ModelOperation):
"""Rename a model."""
"""Rename a model. ( with move model to new_app capability )"""

def __init__(self, old_name, new_name):
def __init__(self, old_name, new_name, new_app_label=None):
self.old_name = old_name
self.new_name = new_name
self.new_app_label = new_app_label
super().__init__(old_name)

@cached_property
Expand All @@ -295,20 +296,24 @@ def deconstruct(self):
'old_name': self.old_name,
'new_name': self.new_name,
}
if self.new_app_label:
kwargs['new_app_label'] = self.new_app_label
return (
self.__class__.__qualname__,
[],
kwargs
)

def state_forwards(self, app_label, state):
new_app_label = self.new_app_label or app_label
# Add a new model.
renamed_model = state.models[app_label, self.old_name_lower].clone()
renamed_model.name = self.new_name
state.models[app_label, self.new_name_lower] = renamed_model
renamed_model.app_label = new_app_label
state.models[new_app_label, self.new_name_lower] = renamed_model
# Repoint all fields pointing to the old model to the new one.
old_model_tuple = ModelTuple(app_label, self.old_name_lower)
new_remote_model = '%s.%s' % (app_label, self.new_name)
new_remote_model = '%s.%s' % (new_app_label, self.new_name)
to_reload = []
for (model_app_label, model_name), model_state in state.models.items():
model_changed = False
Expand Down Expand Up @@ -340,10 +345,11 @@ def state_forwards(self, app_label, state):
state.reload_models(to_reload, delay=True)
# Remove the old model.
state.remove_model(app_label, self.old_name_lower)
state.reload_model(app_label, self.new_name_lower, delay=True)
state.reload_model(new_app_label, self.new_name_lower, delay=True)

def database_forwards(self, app_label, schema_editor, from_state, to_state):
new_model = to_state.apps.get_model(app_label, self.new_name)
new_app_label = self.new_app_label or app_label
new_model = to_state.apps.get_model(new_app_label, self.new_name)
if self.allow_migrate_model(schema_editor.connection.alias, new_model):
old_model = from_state.apps.get_model(app_label, self.old_name)
# Move the main table
Expand All @@ -356,7 +362,7 @@ def database_forwards(self, app_label, schema_editor, from_state, to_state):
for related_object in old_model._meta.related_objects:
if related_object.related_model == old_model:
model = new_model
related_key = (app_label, self.new_name_lower)
related_key = (new_app_label, self.new_name_lower)
else:
model = related_object.related_model
related_key = (
Expand Down Expand Up @@ -394,24 +400,37 @@ def database_forwards(self, app_label, schema_editor, from_state, to_state):
)

def database_backwards(self, app_label, schema_editor, from_state, to_state):
is_moving = bool(self.new_app_label)
self.new_name_lower, self.old_name_lower = self.old_name_lower, self.new_name_lower
self.new_name, self.old_name = self.old_name, self.new_name
if is_moving:
self.new_app_label, app_label = app_label, self.new_app_label

self.database_forwards(app_label, schema_editor, from_state, to_state)

self.new_name_lower, self.old_name_lower = self.old_name_lower, self.new_name_lower
self.new_name, self.old_name = self.old_name, self.new_name
if is_moving:
self.new_app_label, app_label = app_label, self.new_app_label

def references_model(self, name, app_label=None):
# TODO: update references_model for moving
return (
name.lower() == self.old_name_lower or
name.lower() == self.new_name_lower
)

def describe(self):
return "Rename model %s to %s" % (self.old_name, self.new_name)
if self.new_app_label:
if self.old_name == self.new_name:
return "Move model %s to %s.%s" % (self.old_name, self.new_app_label, self.new_name)
else:
return "Rename and Move model %s to %s.%s" % (self.old_name, self.new_app_label, self.new_name)
else:
return "Rename model %s to %s" % (self.old_name, self.new_name)

def reduce(self, operation, app_label=None):
# TODO: update reduce for moving
if (isinstance(operation, RenameModel) and
self.new_name_lower == operation.old_name_lower):
return [
Expand All @@ -428,6 +447,43 @@ def reduce(self, operation, app_label=None):
)


class MoveModelPlaceholder(Operation):
_comment = 'this is a required noop operation to construct dependencies for moving model'

reduces_to_sql = False

def __init__(self, old_name, new_name, new_app_label=None, comment=None, *args, **kwargs):
self.old_name = old_name
self.new_name = new_name
self.new_app_label = new_app_label
super().__init__(*args, **kwargs)

def deconstruct(self):
kwargs = {
'old_name': self.old_name,
'new_name': self.new_name,
'new_app_label': self.new_app_label,
'comment': self._comment # tricky way to put comment in generated migration file
}
return (
self.__class__.__qualname__,
[],
kwargs
)

def state_forwards(self, app_label, state):
pass

def database_forwards(self, app_label, schema_editor, from_state, to_state):
pass

def database_backwards(self, app_label, schema_editor, from_state, to_state):
pass

def describe(self):
return "Move model %s to %s.%s (placeholder)" % (self.old_name, self.new_app_label, self.new_name)


class ModelOptionOperation(ModelOperation):
def reduce(self, operation, app_label=None):
if isinstance(operation, (self.__class__, DeleteModel)) and self.name_lower == operation.name_lower:
Expand Down