Autodetect ForeignKeys and add dependencies/split on circulars
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Andrew Godwin
parent
48493cff73
commit
e2d7e83256
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@ -36,19 +36,87 @@ class MigrationAutodetector(object):
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"""
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# We'll store migrations as lists by app names for now
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self.migrations = {}
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# Adding models.
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old_app_cache = self.from_state.render()
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new_app_cache = self.to_state.render()
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# Adding models. Phase 1 is adding models with no outward relationships.
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added_models = set(self.to_state.models.keys()) - set(self.from_state.models.keys())
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pending_add = {}
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for app_label, model_name in added_models:
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model_state = self.to_state.models[app_label, model_name]
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# Are there any relationships out from this model? if so, punt it to the next phase.
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related_fields = []
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for field in new_app_cache.get_model(app_label, model_name)._meta.fields:
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if hasattr(field, "rel"):
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if hasattr(field.rel, "to"):
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related_fields.append((field.name, field.rel.to._meta.app_label.lower(), field.rel.to._meta.object_name.lower()))
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if hasattr(field.rel, "through") and not field.rel.though._meta.auto_created:
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related_fields.append((field.name, field.rel.through._meta.app_label.lower(), field.rel.through._meta.object_name.lower()))
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if related_fields:
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pending_add[app_label, model_name] = related_fields
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else:
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self.add_to_migration(
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app_label,
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operations.CreateModel(
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name = model_state.name,
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fields = model_state.fields,
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options = model_state.options,
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bases = model_state.bases,
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)
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)
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# Phase 2 is progressively adding pending models, splitting up into two
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# migrations if required.
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pending_new_fks = []
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while pending_add:
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# Is there one we can add that has all dependencies satisfied?
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satisfied = [(m, rf) for m, rf in pending_add.items() if all((al, mn) not in pending_add for f, al, mn in rf)]
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if satisfied:
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(app_label, model_name), related_fields = sorted(satisfied)[0]
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model_state = self.to_state.models[app_label, model_name]
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self.add_to_migration(
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app_label,
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operations.CreateModel(
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name = model_state.name,
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fields = model_state.fields,
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options = model_state.options,
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bases = model_state.bases,
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)
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)
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for field_name, other_app_label, other_model_name in related_fields:
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self.add_dependency(app_label, other_app_label)
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del pending_add[app_label, model_name]
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# Ah well, we'll need to split one. Pick deterministically.
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else:
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(app_label, model_name), related_fields = sorted(pending_add.items())[0]
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model_state = self.to_state.models[app_label, model_name]
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# Work out the fields that need splitting out
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bad_fields = dict((f, (al, mn)) for f, al, mn in related_fields if (al, mn) in pending_add)
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# Create the model, without those
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self.add_to_migration(
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app_label,
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operations.CreateModel(
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name = model_state.name,
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fields = [(n, f) for n, f in model_state.fields if n not in bad_fields],
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options = model_state.options,
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bases = model_state.bases,
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)
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)
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# Add the bad fields to be made in a phase 3
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for field_name, (other_app_label, other_model_name) in bad_fields.items():
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pending_new_fks.append((app_label, model_name, field_name, other_app_label))
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del pending_add[app_label, model_name]
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# Phase 3 is adding the final set of FKs as separate new migrations
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for app_label, model_name, field_name, other_app_label in pending_new_fks:
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model_state = self.to_state.models[app_label, model_name]
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self.add_to_migration(
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app_label,
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operations.CreateModel(
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name = model_state.name,
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fields = model_state.fields,
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options = model_state.options,
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bases = model_state.bases,
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)
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operations.AddField(
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model_name = model_name,
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name = field_name,
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field = model_state.get_field_by_name(field_name),
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),
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new = True,
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)
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self.add_dependency(app_label, other_app_label)
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# Removing models
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removed_models = set(self.from_state.models.keys()) - set(self.to_state.models.keys())
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for app_label, model_name in removed_models:
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@ -127,16 +195,31 @@ class MigrationAutodetector(object):
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for app_label, migrations in self.migrations.items():
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for m1, m2 in zip(migrations, migrations[1:]):
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m2.dependencies.append((app_label, m1.name))
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# Clean up dependencies
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for app_label, migrations in self.migrations.items():
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for migration in migrations:
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migration.dependencies = list(set(migration.dependencies))
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return self.migrations
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def add_to_migration(self, app_label, operation):
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def add_to_migration(self, app_label, operation, new=False):
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migrations = self.migrations.setdefault(app_label, [])
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if not migrations:
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if not migrations or new:
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subclass = type("Migration", (Migration,), {"operations": [], "dependencies": []})
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instance = subclass("auto_%i" % (len(migrations) + 1), app_label)
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migrations.append(instance)
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migrations[-1].operations.append(operation)
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def add_dependency(self, app_label, other_app_label):
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"""
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Adds a dependency to app_label's newest migration on
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other_app_label's latest migration.
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"""
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if self.migrations.get(other_app_label, []):
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dependency = (other_app_label, self.migrations[other_app_label][-1].name)
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else:
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dependency = (other_app_label, "__first__")
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self.migrations[app_label][-1].dependencies.append(dependency)
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def arrange_for_graph(self, changes, graph):
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"""
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Takes in a result from changes() and a MigrationGraph,
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@ -70,7 +70,7 @@ class ModelState(object):
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"""
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# Deconstruct the fields
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fields = []
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for field in model._meta.local_fields:
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for field in model._meta.fields:
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name, path, args, kwargs = field.deconstruct()
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field_class = import_by_path(path)
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fields.append((name, field_class(*args, **kwargs)))
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@ -83,12 +83,15 @@ class ModelState(object):
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if name in model._meta.original_attrs:
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options[name] = model._meta.original_attrs[name]
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# Make our record
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bases = tuple(model for model in model.__bases__ if (not hasattr(model, "_meta") or not model._meta.abstract))
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if not bases:
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bases = (models.Model, )
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return cls(
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model._meta.app_label,
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model._meta.object_name,
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fields,
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options,
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model.__bases__,
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bases,
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)
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def clone(self):
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@ -15,9 +15,12 @@ class AutodetectorTests(TestCase):
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author_name = ModelState("testapp", "Author", [("id", models.AutoField(primary_key=True)), ("name", models.CharField(max_length=200))])
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author_name_longer = ModelState("testapp", "Author", [("id", models.AutoField(primary_key=True)), ("name", models.CharField(max_length=400))])
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author_name_renamed = ModelState("testapp", "Author", [("id", models.AutoField(primary_key=True)), ("names", models.CharField(max_length=200))])
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author_with_book = ModelState("testapp", "Author", [("id", models.AutoField(primary_key=True)), ("name", models.CharField(max_length=200)), ("book", models.ForeignKey("otherapp.Book"))])
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other_pony = ModelState("otherapp", "Pony", [("id", models.AutoField(primary_key=True))])
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other_stable = ModelState("otherapp", "Stable", [("id", models.AutoField(primary_key=True))])
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third_thing = ModelState("thirdapp", "Thing", [("id", models.AutoField(primary_key=True))])
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book = ModelState("otherapp", "Book", [("id", models.AutoField(primary_key=True)), ("author", models.ForeignKey("testapp.Author")), ("title", models.CharField(max_length=200))])
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edition = ModelState("thirdapp", "Edition", [("id", models.AutoField(primary_key=True)), ("book", models.ForeignKey("otherapp.Book"))])
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def make_project_state(self, model_states):
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"Shortcut to make ProjectStates from lists of predefined models"
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@ -167,3 +170,67 @@ class AutodetectorTests(TestCase):
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self.assertEqual(action.__class__.__name__, "RenameField")
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self.assertEqual(action.old_name, "name")
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self.assertEqual(action.new_name, "names")
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def test_fk_dependency(self):
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"Tests that having a ForeignKey automatically adds a dependency"
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# Make state
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before = self.make_project_state([])
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after = self.make_project_state([self.author_name, self.book, self.edition])
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autodetector = MigrationAutodetector(before, after)
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changes = autodetector.changes()
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# Right number of migrations?
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self.assertEqual(len(changes['testapp']), 1)
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self.assertEqual(len(changes['otherapp']), 1)
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self.assertEqual(len(changes['thirdapp']), 1)
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# Right number of actions?
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migration1 = changes['testapp'][0]
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self.assertEqual(len(migration1.operations), 1)
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migration2 = changes['otherapp'][0]
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self.assertEqual(len(migration2.operations), 1)
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migration3 = changes['thirdapp'][0]
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self.assertEqual(len(migration3.operations), 1)
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# Right actions?
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action = migration1.operations[0]
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self.assertEqual(action.__class__.__name__, "CreateModel")
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action = migration2.operations[0]
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self.assertEqual(action.__class__.__name__, "CreateModel")
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action = migration3.operations[0]
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self.assertEqual(action.__class__.__name__, "CreateModel")
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# Right dependencies?
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self.assertEqual(migration1.dependencies, [])
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self.assertEqual(migration2.dependencies, [("testapp", "auto_1")])
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self.assertEqual(migration3.dependencies, [("otherapp", "auto_1")])
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def test_circular_fk_dependency(self):
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"""
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Tests that having a circular ForeignKey dependency automatically
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resolves the situation into 2 migrations on one side and 1 on the other.
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"""
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# Make state
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before = self.make_project_state([])
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after = self.make_project_state([self.author_with_book, self.book])
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autodetector = MigrationAutodetector(before, after)
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changes = autodetector.changes()
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# Right number of migrations?
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self.assertEqual(len(changes['testapp']), 1)
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self.assertEqual(len(changes['otherapp']), 2)
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# Right number of actions?
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migration1 = changes['testapp'][0]
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self.assertEqual(len(migration1.operations), 1)
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migration2 = changes['otherapp'][0]
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self.assertEqual(len(migration2.operations), 1)
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migration3 = changes['otherapp'][1]
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self.assertEqual(len(migration2.operations), 1)
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# Right actions?
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action = migration1.operations[0]
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self.assertEqual(action.__class__.__name__, "CreateModel")
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action = migration2.operations[0]
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self.assertEqual(action.__class__.__name__, "CreateModel")
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self.assertEqual(len(action.fields), 2)
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action = migration3.operations[0]
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self.assertEqual(action.__class__.__name__, "AddField")
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self.assertEqual(action.name, "author")
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# Right dependencies?
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self.assertEqual(migration1.dependencies, [("otherapp", "auto_1")])
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self.assertEqual(migration2.dependencies, [])
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self.assertEqual(set(migration3.dependencies), set([("otherapp", "auto_1"), ("testapp", "auto_1")]))
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