Implement swappable model support for migrations (c9de1b4a) · Commits · Dom Sekotill / django

django/db/migrations/init.py

+1 −1

Original line number	Diff line number	Diff line
		from .migration import Migration # NOQA
		from .migration import Migration, swappable_dependency # NOQA
		from .operations import * # NOQA

django/db/migrations/autodetector.py

+18 −3

Original line number	Diff line number	Diff line
		@@ -105,7 +105,11 @@ class MigrationAutodetector(object):
		)
		)
		for field_name, other_app_label, other_model_name in related_fields:
		if app_label != other_app_label:
		# If it depends on a swappable something, add a dynamic depend'cy
		swappable_setting = new_apps.get_model(app_label, model_name)._meta.get_field_by_name(field_name)[0].swappable_setting
		if swappable_setting is not None:
		self.add_swappable_dependency(app_label, swappable_setting)
		elif app_label != other_app_label:
		self.add_dependency(app_label, other_app_label)
		del pending_add[app_label, model_name]
		# Ah well, we'll need to split one. Pick deterministically.
		@@ -140,7 +144,11 @@ class MigrationAutodetector(object):
		),
		new=True,
		)
		if app_label != other_app_label:
		# If it depends on a swappable something, add a dynamic depend'cy
		swappable_setting = new_apps.get_model(app_label, model_name)._meta.get_field_by_name(field_name)[0].swappable_setting
		if swappable_setting is not None:
		self.add_swappable_dependency(app_label, swappable_setting)
		elif app_label != other_app_label:
		self.add_dependency(app_label, other_app_label)
		# Removing models
		removed_models = set(old_model_keys) - set(new_model_keys)
		@@ -276,6 +284,13 @@ class MigrationAutodetector(object):
		dependency = (other_app_label, "__first__")
		self.migrations[app_label][-1].dependencies.append(dependency)

		def add_swappable_dependency(self, app_label, setting_name):
		"""
		Adds a dependency to the value of a swappable model setting.
		"""
		dependency = ("__setting__", setting_name)
		self.migrations[app_label][-1].dependencies.append(dependency)

		def _arrange_for_graph(self, changes, graph):
		"""
		Takes in a result from changes() and a MigrationGraph,

django/db/migrations/loader.py

+1 −1

Original line number	Diff line number	Diff line
		@@ -223,7 +223,7 @@ class MigrationLoader(object):
		self.graph.add_node(parent, new_migration)
		self.applied_migrations.add(parent)
		elif parent[0] in self.migrated_apps:
		parent = (parent[0], list(self.graph.root_nodes(parent[0]))[0])
		parent = list(self.graph.root_nodes(parent[0]))[0]
		else:
		raise ValueError("Dependency on unknown app %s" % parent[0])
		self.graph.add_dependency(key, parent)

django/db/migrations/migration.py

+7 −0

Original line number	Diff line number	Diff line
		@@ -127,3 +127,10 @@ class Migration(object):
		to_run.reverse()
		for operation, to_state, from_state in to_run:
		operation.database_backwards(self.app_label, schema_editor, from_state, to_state)


		def swappable_dependency(value):
		"""
		Turns a setting value into a dependency.
		"""
		return (value.split(".", 1)[0], "__first__")

django/db/migrations/writer.py

+26 −1

Original line number	Diff line number	Diff line
		@@ -13,6 +13,20 @@ from django.utils.functional import Promise
		from django.utils import six


		class SettingsReference(str):
		"""
		Special subclass of string which actually references a current settings
		value. It's treated as the value in memory, but serializes out to a
		settings.NAME attribute reference.
		"""

		def __new__(self, value, setting_name):
		return str.__new__(self, value)

		def __init__(self, value, setting_name):
		self.setting_name = setting_name


		class MigrationWriter(object):
		"""
		Takes a Migration instance and is able to produce the contents
		@@ -27,7 +41,6 @@ class MigrationWriter(object):
		Returns a string of the file contents.
		"""
		items = {
		"dependencies": repr(self.migration.dependencies),
		"replaces_str": "",
		}
		imports = set()
		@@ -46,6 +59,15 @@ class MigrationWriter(object):
		arg_strings.append("%s = %s" % (kw, arg_string))
		operation_strings.append("migrations.%s(%s\n )" % (name, "".join("\n %s," % arg for arg in arg_strings)))
		items["operations"] = "[%s\n ]" % "".join("\n %s," % s for s in operation_strings)
		# Format dependencies and write out swappable dependencies right
		items["dependencies"] = "["
		for dependency in self.migration.dependencies:
		if dependency[0] == "__setting__":
		items["dependencies"] += "\n migrations.swappable_dependency(settings.%s)," % dependency[1]
		imports.add("from django.conf import settings")
		else:
		items["dependencies"] += "\n %s," % repr(dependency)
		items["dependencies"] += "\n ]"
		# Format imports nicely
		imports.discard("from django.db import models")
		if not imports:
		@@ -136,6 +158,9 @@ class MigrationWriter(object):
		# Datetimes
		elif isinstance(value, (datetime.datetime, datetime.date)):
		return repr(value), set(["import datetime"])
		# Settings references
		elif isinstance(value, SettingsReference):
		return "settings.%s" % value.setting_name, set(["from django.conf import settings"])
		# Simple types
		elif isinstance(value, six.integer_types + (float, six.binary_type, six.text_type, bool, type(None))):
		return repr(value), set()