def test_loading_squashed_complex(self):
"Tests loading a complex set of squashed migrations"
loader = MigrationLoader(connection)
recorder = MigrationRecorder(connection)
self.addCleanup(recorder.flush)
def num_nodes():
plan = set(loader.graph.forwards_plan(('migrations', '7_auto')))
return len(plan - loader.applied_migrations)
# Empty database: use squashed migration
loader.build_graph()
self.assertEqual(num_nodes(), 5)
# Starting at 1 or 2 should use the squashed migration too
recorder.record_applied("migrations", "1_auto")
loader.build_graph()
self.assertEqual(num_nodes(), 4)
recorder.record_applied("migrations", "2_auto")
loader.build_graph()
self.assertEqual(num_nodes(), 3)
# However, starting at 3 to 5 cannot use the squashed migration
recorder.record_applied("migrations", "3_auto")
loader.build_graph()
self.assertEqual(num_nodes(), 4)
recorder.record_applied("migrations", "4_auto")
loader.build_graph()
self.assertEqual(num_nodes(), 3)
# Starting at 5 to 7 we are passed the squashed migrations
recorder.record_applied("migrations", "5_auto")
loader.build_graph()
self.assertEqual(num_nodes(), 2)
recorder.record_applied("migrations", "6_auto")
loader.build_graph()
self.assertEqual(num_nodes(), 1)
recorder.record_applied("migrations", "7_auto")
loader.build_graph()
self.assertEqual(num_nodes(), 0)
def test_migrate_marks_replacement_applied_even_if_it_did_nothing(self):
"""
A new squash migration will be marked as applied even if all its
replaced migrations were previously already applied (#24628).
"""
recorder = MigrationRecorder(connection)
# Record all replaced migrations as applied
recorder.record_applied("migrations", "0001_initial")
recorder.record_applied("migrations", "0002_second")
executor = MigrationExecutor(connection)
executor.migrate([("migrations", "0001_squashed_0002")])
# Because 0001 and 0002 are both applied, even though this migrate run
# didn't apply anything new, their squashed replacement should be
# marked as applied.
self.assertIn(
("migrations", "0001_squashed_0002"),
recorder.applied_migrations(),
)
def test_apply_all_replaced_marks_replacement_as_applied(self):
"""
Applying all replaced migrations marks replacement as applied (#24628).
"""
recorder = MigrationRecorder(connection)
# Place the database in a state where the replaced migrations are
# partially applied: 0001 is applied, 0002 is not.
recorder.record_applied("migrations", "0001_initial")
executor = MigrationExecutor(connection)
# Use fake because we don't actually have the first migration
# applied, so the second will fail. And there's no need to actually
# create/modify tables here, we're just testing the
# MigrationRecord, which works the same with or without fake.
executor.migrate([("migrations", "0002_second")], fake=True)
# Because we've now applied 0001 and 0002 both, their squashed
# replacement should be marked as applied.
self.assertIn(
("migrations", "0001_squashed_0002"),
recorder.applied_migrations(),
)
def test_loading_squashed(self):
"Tests loading a squashed migration"
migration_loader = MigrationLoader(connection)
recorder = MigrationRecorder(connection)
self.addCleanup(recorder.flush)
# Loading with nothing applied should just give us the one node
self.assertEqual(
len([
x for x in migration_loader.graph.nodes if x[0] == "migrations"
]),
1,
)
# However, fake-apply one migration and it should now use the old two
recorder.record_applied("migrations", "0001_initial")
migration_loader.build_graph()
self.assertEqual(
len([
x for x in migration_loader.graph.nodes if x[0] == "migrations"
]),
2,
)
def tearDown(self):
# Reset applied-migrations state.
for db in connections:
recorder = MigrationRecorder(connections[db])
recorder.migration_qs.filter(app='migrations').delete()
def build_graph(self):
"""
Build a migration dependency graph using both the disk and database.
You'll need to rebuild the graph if you apply migrations. This isn't
usually a problem as generally migration stuff runs in a one-shot process.
"""
# Load disk data
self.load_disk()
# Load database data
if self.connection is None:
self.applied_migrations = set()
else:
recorder = MigrationRecorder(self.connection)
self.applied_migrations = recorder.applied_migrations()
# To start, populate the migration graph with nodes for ALL migrations
# and their dependencies. Also make note of replacing migrations at this step.
self.graph = MigrationGraph()
self.replacements = {}
for key, migration in self.disk_migrations.items():
self.graph.add_node(key, migration)
# Internal (aka same-app) dependencies.
self.add_internal_dependencies(key, migration)
# Replacing migrations.
if migration.replaces:
self.replacements[key] = migration
# Add external dependencies now that the internal ones have been resolved.
for key, migration in self.disk_migrations.items():
self.add_external_dependencies(key, migration)
# Carry out replacements where possible.
for key, migration in self.replacements.items():
# Get applied status of each of this migration's replacement targets.
applied_statuses = [(target in self.applied_migrations)
for target in migration.replaces]
# Ensure the replacing migration is only marked as applied if all of
# its replacement targets are.
if all(applied_statuses):
self.applied_migrations.add(key)
else:
self.applied_migrations.discard(key)
# A replacing migration can be used if either all or none of its
# replacement targets have been applied.
if all(applied_statuses) or (not any(applied_statuses)):
self.graph.remove_replaced_nodes(key, migration.replaces)
else:
# This replacing migration cannot be used because it is partially applied.
# Remove it from the graph and remap dependencies to it (#25945).
self.graph.remove_replacement_node(key, migration.replaces)
# Ensure the graph is consistent.
try:
self.graph.validate_consistency()
except NodeNotFoundError as exc:
# Check if the missing node could have been replaced by any squash
# migration but wasn't because the squash migration was partially
# applied before. In that case raise a more understandable exception
# (#23556).
# Get reverse replacements.
reverse_replacements = {}
for key, migration in self.replacements.items():
for replaced in migration.replaces:
reverse_replacements.setdefault(replaced, set()).add(key)
# Try to reraise exception with more detail.
if exc.node in reverse_replacements:
candidates = reverse_replacements.get(exc.node, set())
is_replaced = any(candidate in self.graph.nodes
for candidate in candidates)
if not is_replaced:
tries = ', '.join('%s.%s' % c for c in candidates)
raise NodeNotFoundError(
"Migration {0} depends on nonexistent node ('{1}', '{2}'). "
"Django tried to replace migration {1}.{2} with any of [{3}] "
"but wasn't able to because some of the replaced migrations "
"are already applied.".format(exc.origin, exc.node[0],
exc.node[1], tries),
exc.node) from exc
raise exc