migrate.py 文件源码

def sync_apps(self, connection, app_labels):
        """Run the old syncdb-style operation on a list of app_labels."""
        with connection.cursor() as cursor:
            tables = connection.introspection.table_names(cursor)

        # Build the manifest of apps and models that are to be synchronized.
        all_models = [
            (
                app_config.label,
                router.get_migratable_models(app_config, connection.alias, include_auto_created=False),
            )
            for app_config in apps.get_app_configs()
            if app_config.models_module is not None and app_config.label in app_labels
        ]

        def model_installed(model):
            opts = model._meta
            converter = connection.introspection.table_name_converter
            return not (
                (converter(opts.db_table) in tables) or
                (opts.auto_created and converter(opts.auto_created._meta.db_table) in tables)
            )

        manifest = OrderedDict(
            (app_name, list(filter(model_installed, model_list)))
            for app_name, model_list in all_models
        )

        # Create the tables for each model
        if self.verbosity >= 1:
            self.stdout.write("  Creating tables...\n")
        with connection.schema_editor() as editor:
            for app_name, model_list in manifest.items():
                for model in model_list:
                    # Never install unmanaged models, etc.
                    if not model._meta.can_migrate(connection):
                        continue
                    if self.verbosity >= 3:
                        self.stdout.write(
                            "    Processing %s.%s model\n" % (app_name, model._meta.object_name)
                        )
                    if self.verbosity >= 1:
                        self.stdout.write("    Creating table %s\n" % model._meta.db_table)
                    editor.create_model(model)

            # Deferred SQL is executed when exiting the editor's context.
            if self.verbosity >= 1:
                self.stdout.write("    Running deferred SQL...\n")