import sys import os import operator from optparse import make_option from django.apps import apps from django.core.management.base import BaseCommand, CommandError from django.db import connections, DEFAULT_DB_ALIAS, migrations from django.db.migrations.loader import MigrationLoader from django.db.migrations.autodetector import MigrationAutodetector from django.db.migrations.questioner import MigrationQuestioner, InteractiveMigrationQuestioner from django.db.migrations.state import ProjectState from django.db.migrations.writer import MigrationWriter from django.utils.six.moves import reduce class Command(BaseCommand): option_list = BaseCommand.option_list + ( make_option('--dry-run', action='store_true', dest='dry_run', default=False, help="Just show what migrations would be made; don't actually write them."), make_option('--merge', action='store_true', dest='merge', default=False, help="Enable fixing of migration conflicts."), ) help = "Creates new migration(s) for apps." usage_str = "Usage: ./manage.py makemigrations [--dry-run] [app [app ...]]" def handle(self, *app_labels, **options): self.verbosity = int(options.get('verbosity')) self.interactive = options.get('interactive') self.dry_run = options.get('dry_run', False) self.merge = options.get('merge', False) # Make sure the app they asked for exists app_labels = set(app_labels) bad_app_labels = set() for app_label in app_labels: try: apps.get_app_config(app_label) except LookupError: bad_app_labels.add(app_label) if bad_app_labels: for app_label in bad_app_labels: self.stderr.write("App '%s' could not be found. Is it in INSTALLED_APPS?" % app_label) sys.exit(2) # Load the current graph state. Takes a connection, but it's not used # (makemigrations doesn't look at the database state). loader = MigrationLoader(connections[DEFAULT_DB_ALIAS]) # Before anything else, see if there's conflicting apps and drop out # hard if there are any and they don't want to merge conflicts = loader.detect_conflicts() if conflicts and not self.merge: name_str = "; ".join( "%s in %s" % (", ".join(names), app) for app, names in conflicts.items() ) raise CommandError("Conflicting migrations detected (%s).\nTo fix them run 'python manage.py makemigrations --merge'" % name_str) # If they want to merge and there's nothing to merge, then politely exit if self.merge and not conflicts: self.stdout.write("No conflicts detected to merge.") return # If they want to merge and there is something to merge, then # divert into the merge code if self.merge and conflicts: return self.handle_merge(loader, conflicts) # Detect changes autodetector = MigrationAutodetector( loader.graph.project_state(), ProjectState.from_apps(apps), InteractiveMigrationQuestioner(specified_apps=app_labels), ) changes = autodetector.changes(graph=loader.graph, trim_to_apps=app_labels or None) # No changes? Tell them. if not changes and self.verbosity >= 1: if len(app_labels) == 1: self.stdout.write("No changes detected in app '%s'" % app_labels.pop()) elif len(app_labels) > 1: self.stdout.write("No changes detected in apps '%s'" % ("', '".join(app_labels))) else: self.stdout.write("No changes detected") return directory_created = {} for app_label, app_migrations in changes.items(): if self.verbosity >= 1: self.stdout.write(self.style.MIGRATE_HEADING("Migrations for '%s':" % app_label) + "\n") for migration in app_migrations: # Describe the migration writer = MigrationWriter(migration) if self.verbosity >= 1: self.stdout.write(" %s:\n" % (self.style.MIGRATE_LABEL(writer.filename),)) for operation in migration.operations: self.stdout.write(" - %s\n" % operation.describe()) # Write it if not self.dry_run: migrations_directory = os.path.dirname(writer.path) if not directory_created.get(app_label, False): if not os.path.isdir(migrations_directory): os.mkdir(migrations_directory) init_path = os.path.join(migrations_directory, "__init__.py") if not os.path.isfile(init_path): open(init_path, "w").close() # We just do this once per app directory_created[app_label] = True migration_string = writer.as_string() with open(writer.path, "wb") as fh: fh.write(migration_string) def handle_merge(self, loader, conflicts): """ Handles merging together conflicted migrations interactively, if it's safe; otherwise, advises on how to fix it. """ if self.interactive: questioner = InteractiveMigrationQuestioner() else: questioner = MigrationQuestioner() for app_label, migration_names in conflicts.items(): # Grab out the migrations in question, and work out their # common ancestor. merge_migrations = [] for migration_name in migration_names: migration = loader.get_migration(app_label, migration_name) migration.ancestry = loader.graph.forwards_plan((app_label, migration_name)) merge_migrations.append(migration) common_ancestor = None for level in zip(*[m.ancestry for m in merge_migrations]): if reduce(operator.eq, level): common_ancestor = level[0] else: break if common_ancestor is None: raise ValueError("Could not find common ancestor of %s" % migration_names) # Now work out the operations along each divergent branch for migration in merge_migrations: migration.branch = migration.ancestry[ (migration.ancestry.index(common_ancestor) + 1): ] migration.merged_operations = [] for node_app, node_name in migration.branch: migration.merged_operations.extend( loader.get_migration(node_app, node_name).operations ) # In future, this could use some of the Optimizer code # (can_optimize_through) to automatically see if they're # mergeable. For now, we always just prompt the user. if self.verbosity > 0: self.stdout.write(self.style.MIGRATE_HEADING("Merging %s" % app_label)) for migration in merge_migrations: self.stdout.write(self.style.MIGRATE_LABEL(" Branch %s" % migration.name)) for operation in migration.merged_operations: self.stdout.write(" - %s\n" % operation.describe()) if questioner.ask_merge(app_label): # If they still want to merge it, then write out an empty # file depending on the migrations needing merging. numbers = [ MigrationAutodetector.parse_number(migration.name) for migration in merge_migrations ] try: biggest_number = max([x for x in numbers if x is not None]) except ValueError: biggest_number = 1 subclass = type("Migration", (migrations.Migration, ), { "dependencies": [(app_label, migration.name) for migration in merge_migrations], }) new_migration = subclass("%04i_merge" % (biggest_number + 1), app_label) writer = MigrationWriter(new_migration) with open(writer.path, "wb") as fh: fh.write(writer.as_string()) if self.verbosity > 0: self.stdout.write("\nCreated new merge migration %s" % writer.path)