import functools import re from itertools import chain from django.conf import settings from django.db import models from django.db.migrations import operations from django.db.migrations.migration import Migration from django.db.migrations.operations.models import AlterModelOptions from django.db.migrations.optimizer import MigrationOptimizer from django.db.migrations.questioner import MigrationQuestioner from django.db.migrations.utils import ( COMPILED_REGEX_TYPE, RegexObject, get_migration_name_timestamp, ) from django.utils.topological_sort import stable_topological_sort class MigrationAutodetector: """ Take a pair of ProjectStates and compare them to see what the first would need doing to make it match the second (the second usually being the project's current state). Note that this naturally operates on entire projects at a time, as it's likely that changes interact (for example, you can't add a ForeignKey without having a migration to add the table it depends on first). A user interface may offer single-app usage if it wishes, with the caveat that it may not always be possible. """ def __init__(self, from_state, to_state, questioner=None): self.from_state = from_state self.to_state = to_state self.questioner = questioner or MigrationQuestioner() self.existing_apps = {app for app, model in from_state.models} def changes(self, graph, trim_to_apps=None, convert_apps=None, migration_name=None): """ Main entry point to produce a list of applicable changes. Take a graph to base names on and an optional set of apps to try and restrict to (restriction is not guaranteed) """ changes = self._detect_changes(convert_apps, graph) changes = self.arrange_for_graph(changes, graph, migration_name) if trim_to_apps: changes = self._trim_to_apps(changes, trim_to_apps) return changes def deep_deconstruct(self, obj): """ Recursive deconstruction for a field and its arguments. Used for full comparison for rename/alter; sometimes a single-level deconstruction will not compare correctly. """ if isinstance(obj, list): return [self.deep_deconstruct(value) for value in obj] elif isinstance(obj, tuple): return tuple(self.deep_deconstruct(value) for value in obj) elif isinstance(obj, dict): return { key: self.deep_deconstruct(value) for key, value in obj.items() } elif isinstance(obj, functools.partial): return (obj.func, self.deep_deconstruct(obj.args), self.deep_deconstruct(obj.keywords)) elif isinstance(obj, COMPILED_REGEX_TYPE): return RegexObject(obj) elif isinstance(obj, type): # If this is a type that implements 'deconstruct' as an instance method, # avoid treating this as being deconstructible itself - see #22951 return obj elif hasattr(obj, 'deconstruct'): deconstructed = obj.deconstruct() if isinstance(obj, models.Field): # we have a field which also returns a name deconstructed = deconstructed[1:] path, args, kwargs = deconstructed return ( path, [self.deep_deconstruct(value) for value in args], { key: self.deep_deconstruct(value) for key, value in kwargs.items() }, ) else: return obj def only_relation_agnostic_fields(self, fields): """ Return a definition of the fields that ignores field names and what related fields actually relate to. Used for detecting renames (as, of course, the related fields change during renames). """ fields_def = [] for name, field in sorted(fields): deconstruction = self.deep_deconstruct(field) if field.remote_field and field.remote_field.model: del deconstruction[2]['to'] fields_def.append(deconstruction) return fields_def def _detect_changes(self, convert_apps=None, graph=None): """ Return a dict of migration plans which will achieve the change from from_state to to_state. The dict has app labels as keys and a list of migrations as values. The resulting migrations aren't specially named, but the names do matter for dependencies inside the set. convert_apps is the list of apps to convert to use migrations (i.e. to make initial migrations for, in the usual case) graph is an optional argument that, if provided, can help improve dependency generation and avoid potential circular dependencies. """ # The first phase is generating all the operations for each app # and gathering them into a big per-app list. # Then go through that list, order it, and split into migrations to # resolve dependencies caused by M2Ms and FKs. self.generated_operations = {} self.altered_indexes = {} self.altered_constraints = {} # Prepare some old/new state and model lists, separating # proxy models and ignoring unmigrated apps. self.old_apps = self.from_state.concrete_apps self.new_apps = self.to_state.apps self.old_model_keys = set() self.old_proxy_keys = set() self.old_unmanaged_keys = set() self.new_model_keys = set() self.new_proxy_keys = set() self.new_unmanaged_keys = set() for al, mn in self.from_state.models: model = self.old_apps.get_model(al, mn) if not model._meta.managed: self.old_unmanaged_keys.add((al, mn)) elif al not in self.from_state.real_apps: if model._meta.proxy: self.old_proxy_keys.add((al, mn)) else: self.old_model_keys.add((al, mn)) for al, mn in self.to_state.models: model = self.new_apps.get_model(al, mn) if not model._meta.managed: self.new_unmanaged_keys.add((al, mn)) elif ( al not in self.from_state.real_apps or (convert_apps and al in convert_apps) ): if model._meta.proxy: self.new_proxy_keys.add((al, mn)) else: self.new_model_keys.add((al, mn)) # Renames have to come first self.generate_renamed_models() # Prepare lists of fields and generate through model map self._prepare_field_lists() self._generate_through_model_map() # Generate non-rename model operations self.generate_deleted_models() self.generate_created_models() self.generate_deleted_proxies() self.generate_created_proxies() self.generate_altered_options() self.generate_altered_managers() # Create the altered indexes and store them in self.altered_indexes. # This avoids the same computation in generate_removed_indexes() # and generate_added_indexes(). self.create_altered_indexes() self.create_altered_constraints() # Generate index removal operations before field is removed self.generate_removed_constraints() self.generate_removed_indexes() # Generate field operations self.generate_renamed_fields() self.generate_removed_fields() self.generate_added_fields() self.generate_altered_fields() self.generate_altered_unique_together() self.generate_altered_index_together() self.generate_added_indexes() self.generate_added_constraints() self.generate_altered_db_table() self.generate_altered_order_with_respect_to() self._sort_migrations() self._build_migration_list(graph) self._optimize_migrations() return self.migrations def _prepare_field_lists(self): """ Prepare field lists and a list of the fields that used through models in the old state so dependencies can be made from the through model deletion to the field that uses it. """ self.kept_model_keys = self.old_model_keys & self.new_model_keys self.kept_proxy_keys = self.old_proxy_keys & self.new_proxy_keys self.kept_unmanaged_keys = self.old_unmanaged_keys & self.new_unmanaged_keys self.through_users = {} self.old_field_keys = { (app_label, model_name, x) for app_label, model_name in self.kept_model_keys for x, y in self.from_state.models[ app_label, self.renamed_models.get((app_label, model_name), model_name) ].fields } self.new_field_keys = { (app_label, model_name, x) for app_label, model_name in self.kept_model_keys for x, y in self.to_state.models[app_label, model_name].fields } def _generate_through_model_map(self): """Through model map generation.""" for app_label, model_name in sorted(self.old_model_keys): old_model_name = self.renamed_models.get((app_label, model_name), model_name) old_model_state = self.from_state.models[app_label, old_model_name] for field_name, field in old_model_state.fields: old_field = self.old_apps.get_model(app_label, old_model_name)._meta.get_field(field_name) if (hasattr(old_field, "remote_field") and getattr(old_field.remote_field, "through", None) and not old_field.remote_field.through._meta.auto_created): through_key = ( old_field.remote_field.through._meta.app_label, old_field.remote_field.through._meta.model_name, ) self.through_users[through_key] = (app_label, old_model_name, field_name) @staticmethod def _resolve_dependency(dependency): """ Return the resolved dependency and a boolean denoting whether or not it was swappable. """ if dependency[0] != '__setting__': return dependency, False resolved_app_label, resolved_object_name = getattr(settings, dependency[1]).split('.') return (resolved_app_label, resolved_object_name.lower()) + dependency[2:], True def _build_migration_list(self, graph=None): """ Chop the lists of operations up into migrations with dependencies on each other. Do this by going through an app's list of operations until one is found that has an outgoing dependency that isn't in another app's migration yet (hasn't been chopped off its list). Then chop off the operations before it into a migration and move onto the next app. If the loops completes without doing anything, there's a circular dependency (which _should_ be impossible as the operations are all split at this point so they can't depend and be depended on). """ self.migrations = {} num_ops = sum(len(x) for x in self.generated_operations.values()) chop_mode = False while num_ops: # On every iteration, we step through all the apps and see if there # is a completed set of operations. # If we find that a subset of the operations are complete we can # try to chop it off from the rest and continue, but we only # do this if we've already been through the list once before # without any chopping and nothing has changed. for app_label in sorted(self.generated_operations): chopped = [] dependencies = set() for operation in list(self.generated_operations[app_label]): deps_satisfied = True operation_dependencies = set() for dep in operation._auto_deps: # Temporarily resolve the swappable dependency to # prevent circular references. While keeping the # dependency checks on the resolved model, add the # swappable dependencies. original_dep = dep dep, is_swappable_dep = self._resolve_dependency(dep) if dep[0] != app_label: # External app dependency. See if it's not yet # satisfied. for other_operation in self.generated_operations.get(dep[0], []): if self.check_dependency(other_operation, dep): deps_satisfied = False break if not deps_satisfied: break else: if is_swappable_dep: operation_dependencies.add((original_dep[0], original_dep[1])) elif dep[0] in self.migrations: operation_dependencies.add((dep[0], self.migrations[dep[0]][-1].name)) else: # If we can't find the other app, we add a first/last dependency, # but only if we've already been through once and checked everything if chop_mode: # If the app already exists, we add a dependency on the last migration, # as we don't know which migration contains the target field. # If it's not yet migrated or has no migrations, we use __first__ if graph and graph.leaf_nodes(dep[0]): operation_dependencies.add(graph.leaf_nodes(dep[0])[0]) else: operation_dependencies.add((dep[0], "__first__")) else: deps_satisfied = False if deps_satisfied: chopped.append(operation) dependencies.update(operation_dependencies) del self.generated_operations[app_label][0] else: break # Make a migration! Well, only if there's stuff to put in it if dependencies or chopped: if not self.generated_operations[app_label] or chop_mode: subclass = type("Migration", (Migration,), {"operations": [], "dependencies": []}) instance = subclass("auto_%i" % (len(self.migrations.get(app_label, [])) + 1), app_label) instance.dependencies = list(dependencies) instance.operations = chopped instance.initial = app_label not in self.existing_apps self.migrations.setdefault(app_label, []).append(instance) chop_mode = False else: self.generated_operations[app_label] = chopped + self.generated_operations[app_label] new_num_ops = sum(len(x) for x in self.generated_operations.values()) if new_num_ops == num_ops: if not chop_mode: chop_mode = True else: raise ValueError("Cannot resolve operation dependencies: %r" % self.generated_operations) num_ops = new_num_ops def _sort_migrations(self): """ Reorder to make things possible. Reordering may be needed so FKs work nicely inside the same app. """ for app_label, ops in sorted(self.generated_operations.items()): # construct a dependency graph for intra-app dependencies dependency_graph = {op: set() for op in ops} for op in ops: for dep in op._auto_deps: # Resolve intra-app dependencies to handle circular # references involving a swappable model. dep = self._resolve_dependency(dep)[0] if dep[0] == app_label: for op2 in ops: if self.check_dependency(op2, dep): dependency_graph[op].add(op2) # we use a stable sort for deterministic tests & general behavior self.generated_operations[app_label] = stable_topological_sort(ops, dependency_graph) def _optimize_migrations(self): # Add in internal dependencies among the migrations for app_label, migrations in self.migrations.items(): for m1, m2 in zip(migrations, migrations[1:]): m2.dependencies.append((app_label, m1.name)) # De-dupe dependencies for migrations in self.migrations.values(): for migration in migrations: migration.dependencies = list(set(migration.dependencies)) # Optimize migrations for app_label, migrations in self.migrations.items(): for migration in migrations: migration.operations = MigrationOptimizer().optimize(migration.operations, app_label=app_label) def check_dependency(self, operation, dependency): """ Return True if the given operation depends on the given dependency, False otherwise. """ # Created model if dependency[2] is None and dependency[3] is True: return ( isinstance(operation, operations.CreateModel) and operation.name_lower == dependency[1].lower() ) # Created field elif dependency[2] is not None and dependency[3] is True: return ( ( isinstance(operation, operations.CreateModel) and operation.name_lower == dependency[1].lower() and any(dependency[2] == x for x, y in operation.fields) ) or ( isinstance(operation, operations.AddField) and operation.model_name_lower == dependency[1].lower() and operation.name_lower == dependency[2].lower() ) ) # Removed field elif dependency[2] is not None and dependency[3] is False: return ( isinstance(operation, operations.RemoveField) and operation.model_name_lower == dependency[1].lower() and operation.name_lower == dependency[2].lower() ) # Removed model elif dependency[2] is None and dependency[3] is False: return ( isinstance(operation, operations.DeleteModel) and operation.name_lower == dependency[1].lower() ) # Field being altered elif dependency[2] is not None and dependency[3] == "alter": return ( isinstance(operation, operations.AlterField) and operation.model_name_lower == dependency[1].lower() and operation.name_lower == dependency[2].lower() ) # order_with_respect_to being unset for a field elif dependency[2] is not None and dependency[3] == "order_wrt_unset": return ( isinstance(operation, operations.AlterOrderWithRespectTo) and operation.name_lower == dependency[1].lower() and (operation.order_with_respect_to or "").lower() != dependency[2].lower() ) # Field is removed and part of an index/unique_together elif dependency[2] is not None and dependency[3] == "foo_together_change": return ( isinstance(operation, (operations.AlterUniqueTogether, operations.AlterIndexTogether)) and operation.name_lower == dependency[1].lower() ) # Unknown dependency. Raise an error. else: raise ValueError("Can't handle dependency %r" % (dependency,)) def add_operation(self, app_label, operation, dependencies=None, beginning=False): # Dependencies are (app_label, model_name, field_name, create/delete as True/False) operation._auto_deps = dependencies or [] if beginning: self.generated_operations.setdefault(app_label, []).insert(0, operation) else: self.generated_operations.setdefault(app_label, []).append(operation) def swappable_first_key(self, item): """ Place potential swappable models first in lists of created models (only real way to solve #22783). """ try: model = self.new_apps.get_model(item[0], item[1]) base_names = [base.__name__ for base in model.__bases__] string_version = "%s.%s" % (item[0], item[1]) if ( model._meta.swappable or "AbstractUser" in base_names or "AbstractBaseUser" in base_names or settings.AUTH_USER_MODEL.lower() == string_version.lower() ): return ("___" + item[0], "___" + item[1]) except LookupError: pass return item def generate_renamed_models(self): """ Find any renamed models, generate the operations for them, and remove the old entry from the model lists. Must be run before other model-level generation. """ self.renamed_models = {} self.renamed_models_rel = {} added_models = self.new_model_keys - self.old_model_keys for app_label, model_name in sorted(added_models): model_state = self.to_state.models[app_label, model_name] model_fields_def = self.only_relation_agnostic_fields(model_state.fields) 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: 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: if self.questioner.ask_rename_model(rem_model_state, model_state): model_opts = self.new_apps.get_model(app_label, model_name)._meta dependencies = [] for field in model_opts.get_fields(): if field.is_relation: dependencies.extend(self._get_dependencies_for_foreign_key(field)) self.add_operation( app_label, operations.RenameModel( old_name=rem_model_state.name, new_name=model_state.name, ), dependencies=dependencies, ) self.renamed_models[app_label, model_name] = rem_model_name renamed_models_rel_key = '%s.%s' % (rem_model_state.app_label, rem_model_state.name) self.renamed_models_rel[renamed_models_rel_key] = '%s.%s' % ( model_state.app_label, model_state.name, ) self.old_model_keys.remove((rem_app_label, rem_model_name)) self.old_model_keys.add((app_label, model_name)) break def generate_created_models(self): """ Find all new models (both managed and unmanaged) and make create operations for them as well as separate operations to create any foreign key or M2M relationships (these are optimized later, if possible). Defer any model options that refer to collections of fields that might be deferred (e.g. unique_together, index_together). """ old_keys = self.old_model_keys | self.old_unmanaged_keys added_models = self.new_model_keys - old_keys added_unmanaged_models = self.new_unmanaged_keys - old_keys all_added_models = chain( sorted(added_models, key=self.swappable_first_key, reverse=True), sorted(added_unmanaged_models, key=self.swappable_first_key, reverse=True) ) for app_label, model_name in all_added_models: model_state = self.to_state.models[app_label, model_name] model_opts = self.new_apps.get_model(app_label, model_name)._meta # Gather related fields related_fields = {} primary_key_rel = None for field in model_opts.local_fields: if field.remote_field: if field.remote_field.model: if field.primary_key: primary_key_rel = field.remote_field.model elif not field.remote_field.parent_link: related_fields[field.name] = field # through will be none on M2Ms on swapped-out models; # we can treat lack of through as auto_created=True, though. if (getattr(field.remote_field, "through", None) and not field.remote_field.through._meta.auto_created): related_fields[field.name] = field for field in model_opts.local_many_to_many: if field.remote_field.model: related_fields[field.name] = field if getattr(field.remote_field, "through", None) and not field.remote_field.through._meta.auto_created: related_fields[field.name] = field # Are there indexes/unique|index_together to defer? indexes = model_state.options.pop('indexes') constraints = model_state.options.pop('constraints') unique_together = model_state.options.pop('unique_together', None) index_together = model_state.options.pop('index_together', None) order_with_respect_to = model_state.options.pop('order_with_respect_to', None) # Depend on the deletion of any possible proxy version of us dependencies = [ (app_label, model_name, None, False), ] # Depend on all bases for base in model_state.bases: if isinstance(base, str) and "." in base: base_app_label, base_name = base.split(".", 1) dependencies.append((base_app_label, base_name, None, True)) # Depend on the other end of the primary key if it's a relation if primary_key_rel: dependencies.append(( primary_key_rel._meta.app_label, primary_key_rel._meta.object_name, None, True )) # Generate creation operation self.add_operation( app_label, operations.CreateModel( name=model_state.name, fields=[d for d in model_state.fields if d[0] not in related_fields], options=model_state.options, bases=model_state.bases, managers=model_state.managers, ), dependencies=dependencies, beginning=True, ) # Don't add operations which modify the database for unmanaged models if not model_opts.managed: continue # Generate operations for each related field for name, field in sorted(related_fields.items()): dependencies = self._get_dependencies_for_foreign_key(field) # Depend on our own model being created dependencies.append((app_label, model_name, None, True)) # Make operation self.add_operation( app_label, operations.AddField( model_name=model_name, name=name, field=field, ), dependencies=list(set(dependencies)), ) # Generate other opns related_dependencies = [ (app_label, model_name, name, True) for name in sorted(related_fields) ] related_dependencies.append((app_label, model_name, None, True)) for index in indexes: self.add_operation( app_label, operations.AddIndex( model_name=model_name, index=index, ), dependencies=related_dependencies, ) for constraint in constraints: self.add_operation( app_label, operations.AddConstraint( model_name=model_name, constraint=constraint, ), dependencies=related_dependencies, ) if unique_together: self.add_operation( app_label, operations.AlterUniqueTogether( name=model_name, unique_together=unique_together, ), dependencies=related_dependencies ) if index_together: self.add_operation( app_label, operations.AlterIndexTogether( name=model_name, index_together=index_together, ), dependencies=related_dependencies ) if order_with_respect_to: self.add_operation( app_label, operations.AlterOrderWithRespectTo( name=model_name, order_with_respect_to=order_with_respect_to, ), dependencies=[ (app_label, model_name, order_with_respect_to, True), (app_label, model_name, None, True), ] ) # Fix relationships if the model changed from a proxy model to a # concrete model. if (app_label, model_name) in self.old_proxy_keys: for related_object in model_opts.related_objects: self.add_operation( related_object.related_model._meta.app_label, operations.AlterField( model_name=related_object.related_model._meta.object_name, name=related_object.field.name, field=related_object.field, ), dependencies=[(app_label, model_name, None, True)], ) def generate_created_proxies(self): """ Make CreateModel statements for proxy models. Use the same statements as that way there's less code duplication, but of course for proxy models it's safe to skip all the pointless field stuff and just chuck out an operation. """ added = self.new_proxy_keys - self.old_proxy_keys for app_label, model_name in sorted(added): model_state = self.to_state.models[app_label, model_name] assert model_state.options.get("proxy") # Depend on the deletion of any possible non-proxy version of us dependencies = [ (app_label, model_name, None, False), ] # Depend on all bases for base in model_state.bases: if isinstance(base, str) and "." in base: base_app_label, base_name = base.split(".", 1) dependencies.append((base_app_label, base_name, None, True)) # Generate creation operation self.add_operation( app_label, operations.CreateModel( name=model_state.name, fields=[], options=model_state.options, bases=model_state.bases, managers=model_state.managers, ), # Depend on the deletion of any possible non-proxy version of us dependencies=dependencies, ) def generate_deleted_models(self): """ Find all deleted models (managed and unmanaged) and make delete operations for them as well as separate operations to delete any foreign key or M2M relationships (these are optimized later, if possible). Also bring forward removal of any model options that refer to collections of fields - the inverse of generate_created_models(). """ new_keys = self.new_model_keys | self.new_unmanaged_keys deleted_models = self.old_model_keys - new_keys deleted_unmanaged_models = self.old_unmanaged_keys - new_keys all_deleted_models = chain(sorted(deleted_models), sorted(deleted_unmanaged_models)) for app_label, model_name in all_deleted_models: model_state = self.from_state.models[app_label, model_name] model = self.old_apps.get_model(app_label, model_name) # Gather related fields related_fields = {} for field in model._meta.local_fields: if field.remote_field: if field.remote_field.model: related_fields[field.name] = field # through will be none on M2Ms on swapped-out models; # we can treat lack of through as auto_created=True, though. if (getattr(field.remote_field, "through", None) and not field.remote_field.through._meta.auto_created): related_fields[field.name] = field for field in model._meta.local_many_to_many: if field.remote_field.model: related_fields[field.name] = field if getattr(field.remote_field, "through", None) and not field.remote_field.through._meta.auto_created: related_fields[field.name] = field # Generate option removal first unique_together = model_state.options.pop('unique_together', None) index_together = model_state.options.pop('index_together', None) if unique_together: self.add_operation( app_label, operations.AlterUniqueTogether( name=model_name, unique_together=None, ) ) if index_together: self.add_operation( app_label, operations.AlterIndexTogether( name=model_name, index_together=None, ) ) # Then remove each related field for name in sorted(related_fields): self.add_operation( app_label, operations.RemoveField( model_name=model_name, name=name, ) ) # Finally, remove the model. # This depends on both the removal/alteration of all incoming fields # and the removal of all its own related fields, and if it's # a through model the field that references it. dependencies = [] for related_object in model._meta.related_objects: related_object_app_label = related_object.related_model._meta.app_label object_name = related_object.related_model._meta.object_name field_name = related_object.field.name dependencies.append((related_object_app_label, object_name, field_name, False)) if not related_object.many_to_many: dependencies.append((related_object_app_label, object_name, field_name, "alter")) for name in sorted(related_fields): dependencies.append((app_label, model_name, name, False)) # We're referenced in another field's through= through_user = self.through_users.get((app_label, model_state.name_lower)) if through_user: dependencies.append((through_user[0], through_user[1], through_user[2], False)) # Finally, make the operation, deduping any dependencies self.add_operation( app_label, operations.DeleteModel( name=model_state.name, ), dependencies=list(set(dependencies)), ) def generate_deleted_proxies(self): """Make DeleteModel options for proxy models.""" deleted = self.old_proxy_keys - self.new_proxy_keys for app_label, model_name in sorted(deleted): model_state = self.from_state.models[app_label, model_name] assert model_state.options.get("proxy") self.add_operation( app_label, operations.DeleteModel( name=model_state.name, ), ) def generate_renamed_fields(self): """Work out renamed fields.""" self.renamed_fields = {} for app_label, model_name, field_name in sorted(self.new_field_keys - self.old_field_keys): old_model_name = self.renamed_models.get((app_label, model_name), model_name) old_model_state = self.from_state.models[app_label, old_model_name] field = self.new_apps.get_model(app_label, model_name)._meta.get_field(field_name) # Scan to see if this is actually a rename! field_dec = self.deep_deconstruct(field) for rem_app_label, rem_model_name, rem_field_name in sorted(self.old_field_keys - self.new_field_keys): if rem_app_label == app_label and rem_model_name == model_name: old_field = old_model_state.get_field_by_name(rem_field_name) old_field_dec = self.deep_deconstruct(old_field) if field.remote_field and field.remote_field.model and 'to' in old_field_dec[2]: old_rel_to = old_field_dec[2]['to'] if old_rel_to in self.renamed_models_rel: old_field_dec[2]['to'] = self.renamed_models_rel[old_rel_to] old_field.set_attributes_from_name(rem_field_name) old_db_column = old_field.get_attname_column()[1] if (old_field_dec == field_dec or ( # Was the field renamed and db_column equal to the # old field's column added? old_field_dec[0:2] == field_dec[0:2] and dict(old_field_dec[2], db_column=old_db_column) == field_dec[2])): if self.questioner.ask_rename(model_name, rem_field_name, field_name, field): self.add_operation( app_label, operations.RenameField( model_name=model_name, old_name=rem_field_name, new_name=field_name, ) ) self.old_field_keys.remove((rem_app_label, rem_model_name, rem_field_name)) self.old_field_keys.add((app_label, model_name, field_name)) self.renamed_fields[app_label, model_name, field_name] = rem_field_name break def generate_added_fields(self): """Make AddField operations.""" for app_label, model_name, field_name in sorted(self.new_field_keys - self.old_field_keys): self._generate_added_field(app_label, model_name, field_name) def _generate_added_field(self, app_label, model_name, field_name): field = self.new_apps.get_model(app_label, model_name)._meta.get_field(field_name) # Fields that are foreignkeys/m2ms depend on stuff dependencies = [] if field.remote_field and field.remote_field.model: dependencies.extend(self._get_dependencies_for_foreign_key(field)) # You can't just add NOT NULL fields with no default or fields # which don't allow empty strings as default. time_fields = (models.DateField, models.DateTimeField, models.TimeField) preserve_default = ( field.null or field.has_default() or field.many_to_many or (field.blank and field.empty_strings_allowed) or (isinstance(field, time_fields) and field.auto_now) ) if not preserve_default: field = field.clone() if isinstance(field, time_fields) and field.auto_now_add: field.default = self.questioner.ask_auto_now_add_addition(field_name, model_name) else: field.default = self.questioner.ask_not_null_addition(field_name, model_name) self.add_operation( app_label, operations.AddField( model_name=model_name, name=field_name, field=field, preserve_default=preserve_default, ), dependencies=dependencies, ) def generate_removed_fields(self): """Make RemoveField operations.""" for app_label, model_name, field_name in sorted(self.old_field_keys - self.new_field_keys): self._generate_removed_field(app_label, model_name, field_name) def _generate_removed_field(self, app_label, model_name, field_name): self.add_operation( app_label, operations.RemoveField( model_name=model_name, name=field_name, ), # We might need to depend on the removal of an # order_with_respect_to or index/unique_together operation; # this is safely ignored if there isn't one dependencies=[ (app_label, model_name, field_name, "order_wrt_unset"), (app_label, model_name, field_name, "foo_together_change"), ], ) def generate_altered_fields(self): """ Make AlterField operations, or possibly RemovedField/AddField if alter isn's possible. """ for app_label, model_name, field_name in sorted(self.old_field_keys & self.new_field_keys): # Did the field change? old_model_name = self.renamed_models.get((app_label, model_name), model_name) old_field_name = self.renamed_fields.get((app_label, model_name, field_name), field_name) old_field = self.old_apps.get_model(app_label, old_model_name)._meta.get_field(old_field_name) new_field = self.new_apps.get_model(app_label, model_name)._meta.get_field(field_name) # Implement any model renames on relations; these are handled by RenameModel # so we need to exclude them from the comparison if hasattr(new_field, "remote_field") and getattr(new_field.remote_field, "model", None): rename_key = ( new_field.remote_field.model._meta.app_label, new_field.remote_field.model._meta.model_name, ) if rename_key in self.renamed_models: new_field.remote_field.model = old_field.remote_field.model # Handle ForeignKey which can only have a single to_field. remote_field_name = getattr(new_field.remote_field, 'field_name', None) if remote_field_name: to_field_rename_key = rename_key + (remote_field_name,) if to_field_rename_key in self.renamed_fields: new_field.remote_field.field_name = old_field.remote_field.field_name # Handle ForeignObjects which can have multiple from_fields/to_fields. from_fields = getattr(new_field, 'from_fields', None) if from_fields: from_rename_key = (app_label, model_name) new_field.from_fields = tuple([ self.renamed_fields.get(from_rename_key + (from_field,), from_field) for from_field in from_fields ]) new_field.to_fields = tuple([ self.renamed_fields.get(rename_key + (to_field,), to_field) for to_field in new_field.to_fields ]) if hasattr(new_field, "remote_field") and getattr(new_field.remote_field, "through", None): rename_key = ( new_field.remote_field.through._meta.app_label, new_field.remote_field.through._meta.model_name, ) if rename_key in self.renamed_models: new_field.remote_field.through = old_field.remote_field.through old_field_dec = self.deep_deconstruct(old_field) new_field_dec = self.deep_deconstruct(new_field) if old_field_dec != new_field_dec: both_m2m = old_field.many_to_many and new_field.many_to_many neither_m2m = not old_field.many_to_many and not new_field.many_to_many if both_m2m or neither_m2m: # Either both fields are m2m or neither is preserve_default = True if (old_field.null and not new_field.null and not new_field.has_default() and not new_field.many_to_many): field = new_field.clone() new_default = self.questioner.ask_not_null_alteration(field_name, model_name) if new_default is not models.NOT_PROVIDED: field.default = new_default preserve_default = False else: field = new_field self.add_operation( app_label, operations.AlterField( model_name=model_name, name=field_name, field=field, preserve_default=preserve_default, ) ) else: # We cannot alter between m2m and concrete fields self._generate_removed_field(app_label, model_name, field_name) self._generate_added_field(app_label, model_name, field_name) def create_altered_indexes(self): option_name = operations.AddIndex.option_name for app_label, model_name in sorted(self.kept_model_keys): old_model_name = self.renamed_models.get((app_label, model_name), model_name) old_model_state = self.from_state.models[app_label, old_model_name] new_model_state = self.to_state.models[app_label, model_name] old_indexes = old_model_state.options[option_name] new_indexes = new_model_state.options[option_name] add_idx = [idx for idx in new_indexes if idx not in old_indexes] rem_idx = [idx for idx in old_indexes if idx not in new_indexes] self.altered_indexes.update({ (app_label, model_name): { 'added_indexes': add_idx, 'removed_indexes': rem_idx, } }) def generate_added_indexes(self): for (app_label, model_name), alt_indexes in self.altered_indexes.items(): for index in alt_indexes['added_indexes']: self.add_operation( app_label, operations.AddIndex( model_name=model_name, index=index, ) ) def generate_removed_indexes(self): for (app_label, model_name), alt_indexes in self.altered_indexes.items(): for index in alt_indexes['removed_indexes']: self.add_operation( app_label, operations.RemoveIndex( model_name=model_name, name=index.name, ) ) def create_altered_constraints(self): option_name = operations.AddConstraint.option_name for app_label, model_name in sorted(self.kept_model_keys): old_model_name = self.renamed_models.get((app_label, model_name), model_name) old_model_state = self.from_state.models[app_label, old_model_name] new_model_state = self.to_state.models[app_label, model_name] old_constraints = old_model_state.options[option_name] new_constraints = new_model_state.options[option_name] add_constraints = [c for c in new_constraints if c not in old_constraints] rem_constraints = [c for c in old_constraints if c not in new_constraints] self.altered_constraints.update({ (app_label, model_name): { 'added_constraints': add_constraints, 'removed_constraints': rem_constraints, } }) def generate_added_constraints(self): for (app_label, model_name), alt_constraints in self.altered_constraints.items(): for constraint in alt_constraints['added_constraints']: self.add_operation( app_label, operations.AddConstraint( model_name=model_name, constraint=constraint, ) ) def generate_removed_constraints(self): for (app_label, model_name), alt_constraints in self.altered_constraints.items(): for constraint in alt_constraints['removed_constraints']: self.add_operation( app_label, operations.RemoveConstraint( model_name=model_name, name=constraint.name, ) ) def _get_dependencies_for_foreign_key(self, field): # Account for FKs to swappable models swappable_setting = getattr(field, 'swappable_setting', None) if swappable_setting is not None: dep_app_label = "__setting__" dep_object_name = swappable_setting else: dep_app_label = field.remote_field.model._meta.app_label dep_object_name = field.remote_field.model._meta.object_name dependencies = [(dep_app_label, dep_object_name, None, True)] if getattr(field.remote_field, "through", None) and not field.remote_field.through._meta.auto_created: dependencies.append(( field.remote_field.through._meta.app_label, field.remote_field.through._meta.object_name, None, True, )) return dependencies def _generate_altered_foo_together(self, operation): option_name = operation.option_name for app_label, model_name in sorted(self.kept_model_keys): old_model_name = self.renamed_models.get((app_label, model_name), model_name) old_model_state = self.from_state.models[app_label, old_model_name] new_model_state = self.to_state.models[app_label, model_name] # We run the old version through the field renames to account for those old_value = old_model_state.options.get(option_name) old_value = { tuple( self.renamed_fields.get((app_label, model_name, n), n) for n in unique ) for unique in old_value } if old_value else set() new_value = new_model_state.options.get(option_name) new_value = set(new_value) if new_value else set() if old_value != new_value: dependencies = [] for foo_togethers in new_value: for field_name in foo_togethers: field = self.new_apps.get_model(app_label, model_name)._meta.get_field(field_name) if field.remote_field and field.remote_field.model: dependencies.extend(self._get_dependencies_for_foreign_key(field)) self.add_operation( app_label, operation( name=model_name, **{option_name: new_value} ), dependencies=dependencies, ) def generate_altered_unique_together(self): self._generate_altered_foo_together(operations.AlterUniqueTogether) def generate_altered_index_together(self): self._generate_altered_foo_together(operations.AlterIndexTogether) def generate_altered_db_table(self): models_to_check = self.kept_model_keys.union(self.kept_proxy_keys, self.kept_unmanaged_keys) for app_label, model_name in sorted(models_to_check): old_model_name = self.renamed_models.get((app_label, model_name), model_name) old_model_state = self.from_state.models[app_label, old_model_name] new_model_state = self.to_state.models[app_label, model_name] old_db_table_name = old_model_state.options.get('db_table') new_db_table_name = new_model_state.options.get('db_table') if old_db_table_name != new_db_table_name: self.add_operation( app_label, operations.AlterModelTable( name=model_name, table=new_db_table_name, ) ) def generate_altered_options(self): """ Work out if any non-schema-affecting options have changed and make an operation to represent them in state changes (in case Python code in migrations needs them). """ models_to_check = self.kept_model_keys.union( self.kept_proxy_keys, self.kept_unmanaged_keys, # unmanaged converted to managed self.old_unmanaged_keys & self.new_model_keys, # managed converted to unmanaged self.old_model_keys & self.new_unmanaged_keys, ) for app_label, model_name in sorted(models_to_check): old_model_name = self.renamed_models.get((app_label, model_name), model_name) old_model_state = self.from_state.models[app_label, old_model_name] new_model_state = self.to_state.models[app_label, model_name] old_options = { key: value for key, value in old_model_state.options.items() if key in AlterModelOptions.ALTER_OPTION_KEYS } new_options = { key: value for key, value in new_model_state.options.items() if key in AlterModelOptions.ALTER_OPTION_KEYS } if old_options != new_options: self.add_operation( app_label, operations.AlterModelOptions( name=model_name, options=new_options, ) ) def generate_altered_order_with_respect_to(self): for app_label, model_name in sorted(self.kept_model_keys): old_model_name = self.renamed_models.get((app_label, model_name), model_name) old_model_state = self.from_state.models[app_label, old_model_name] new_model_state = self.to_state.models[app_label, model_name] if (old_model_state.options.get("order_with_respect_to") != new_model_state.options.get("order_with_respect_to")): # Make sure it comes second if we're adding # (removal dependency is part of RemoveField) dependencies = [] if new_model_state.options.get("order_with_respect_to"): dependencies.append(( app_label, model_name, new_model_state.options["order_with_respect_to"], True, )) # Actually generate the operation self.add_operation( app_label, operations.AlterOrderWithRespectTo( name=model_name, order_with_respect_to=new_model_state.options.get('order_with_respect_to'), ), dependencies=dependencies, ) def generate_altered_managers(self): for app_label, model_name in sorted(self.kept_model_keys): old_model_name = self.renamed_models.get((app_label, model_name), model_name) old_model_state = self.from_state.models[app_label, old_model_name] new_model_state = self.to_state.models[app_label, model_name] if old_model_state.managers != new_model_state.managers: self.add_operation( app_label, operations.AlterModelManagers( name=model_name, managers=new_model_state.managers, ) ) def arrange_for_graph(self, changes, graph, migration_name=None): """ Take a result from changes() and a MigrationGraph, and fix the names and dependencies of the changes so they extend the graph from the leaf nodes for each app. """ leaves = graph.leaf_nodes() name_map = {} for app_label, migrations in list(changes.items()): if not migrations: continue # Find the app label's current leaf node app_leaf = None for leaf in leaves: if leaf[0] == app_label: app_leaf = leaf break # Do they want an initial migration for this app? if app_leaf is None and not self.questioner.ask_initial(app_label): # They don't. for migration in migrations: name_map[(app_label, migration.name)] = (app_label, "__first__") del changes[app_label] continue # Work out the next number in the sequence if app_leaf is None: next_number = 1 else: next_number = (self.parse_number(app_leaf[1]) or 0) + 1 # Name each migration for i, migration in enumerate(migrations): if i == 0 and app_leaf: migration.dependencies.append(app_leaf) if i == 0 and not app_leaf: new_name = "0001_%s" % migration_name if migration_name else "0001_initial" else: new_name = "%04i_%s" % ( next_number, migration_name or self.suggest_name(migration.operations)[:100], ) name_map[(app_label, migration.name)] = (app_label, new_name) next_number += 1 migration.name = new_name # Now fix dependencies for migrations in changes.values(): for migration in migrations: migration.dependencies = [name_map.get(d, d) for d in migration.dependencies] return changes def _trim_to_apps(self, changes, app_labels): """ Take changes from arrange_for_graph() and set of app labels, and return a modified set of changes which trims out as many migrations that are not in app_labels as possible. Note that some other migrations may still be present as they may be required dependencies. """ # Gather other app dependencies in a first pass app_dependencies = {} for app_label, migrations in changes.items(): for migration in migrations: for dep_app_label, name in migration.dependencies: app_dependencies.setdefault(app_label, set()).add(dep_app_label) required_apps = set(app_labels) # Keep resolving till there's no change old_required_apps = None while old_required_apps != required_apps: old_required_apps = set(required_apps) required_apps.update(*[app_dependencies.get(app_label, ()) for app_label in required_apps]) # Remove all migrations that aren't needed for app_label in list(changes): if app_label not in required_apps: del changes[app_label] return changes @classmethod def suggest_name(cls, ops): """ Given a set of operations, suggest a name for the migration they might represent. Names are not guaranteed to be unique, but put some effort into the fallback name to avoid VCS conflicts if possible. """ if len(ops) == 1: if isinstance(ops[0], operations.CreateModel): return ops[0].name_lower elif isinstance(ops[0], operations.DeleteModel): return "delete_%s" % ops[0].name_lower elif isinstance(ops[0], operations.AddField): return "%s_%s" % (ops[0].model_name_lower, ops[0].name_lower) elif isinstance(ops[0], operations.RemoveField): return "remove_%s_%s" % (ops[0].model_name_lower, ops[0].name_lower) elif ops: if all(isinstance(o, operations.CreateModel) for o in ops): return "_".join(sorted(o.name_lower for o in ops)) return "auto_%s" % get_migration_name_timestamp() @classmethod def parse_number(cls, name): """ Given a migration name, try to extract a number from the beginning of it. If no number is found, return None. """ match = re.match(r'^\d+', name) if match: return int(match.group()) return None