Make migrate command recognise prefixes and 'zero'.

django/core/management/commands/migrate.py

@@ -4,17 +4,18 @@ import traceback
 
 from django.conf import settings
 from django.core.management import call_command
-from django.core.management.base import NoArgsCommand
+from django.core.management.base import BaseCommand, CommandError
 from django.core.management.color import color_style, no_style
 from django.core.management.sql import custom_sql_for_model, emit_post_sync_signal, emit_pre_sync_signal
 from django.db import connections, router, transaction, models, DEFAULT_DB_ALIAS
 from django.db.migrations.executor import MigrationExecutor
+from django.db.migrations.loader import AmbiguityError
 from django.utils.datastructures import SortedDict
 from django.utils.importlib import import_module
 
 
-class Command(NoArgsCommand):
-    option_list = NoArgsCommand.option_list + (
+class Command(BaseCommand):
+    option_list = BaseCommand.option_list + (
         make_option('--noinput', action='store_false', dest='interactive', default=True,
             help='Tells Django to NOT prompt the user for input of any kind.'),
         make_option('--no-initial-data', action='store_false', dest='load_initial_data', default=True,
@@ -26,7 +27,7 @@ class Command(NoArgsCommand):
 
     help = "Updates database schema. Manages both apps with migrations and those without."
 
-    def handle_noargs(self, **options):
+    def handle(self, *args, **options):
 
         self.verbosity = int(options.get('verbosity'))
         self.interactive = options.get('interactive')
@@ -60,24 +61,57 @@ class Command(NoArgsCommand):
         connection = connections[db]
 
         # Work out which apps have migrations and which do not
-        if self.verbosity >= 1:
-            self.stdout.write(self.style.MIGRATE_HEADING("Calculating migration plan:"))
         executor = MigrationExecutor(connection, self.migration_progress_callback)
-        if self.verbosity >= 1:
-            self.stdout.write(self.style.MIGRATE_LABEL("  Apps without migrations: ") + (", ".join(executor.loader.unmigrated_apps) or "(none)"))
 
-        # Work out what targets they want, and then make a migration plan
-        # TODO: Let users select targets
-        targets = executor.loader.graph.leaf_nodes()
+        # If they supplied command line arguments, work out what they mean.
+        run_syncdb = False
+        target_app_labels_only = True
+        if len(args) > 2:
+            raise CommandError("Too many command-line arguments (expecting 'appname' or 'appname migrationname')")
+        elif len(args) == 2:
+            app_label, migration_name = args
+            if app_label not in executor.loader.migrated_apps:
+                raise CommandError("App '%s' does not have migrations (you cannot selectively sync unmigrated apps)" % app_label)
+            if migration_name == "zero":
+                migration_name = None
+            else:
+                try:
+                    migration = executor.loader.get_migration_by_prefix(app_label, migration_name)
+                except AmbiguityError:
+                    raise CommandError("More than one migration matches '%s' in app '%s'. Please be more specific." % (app_label, migration_name))
+                except KeyError:
+                    raise CommandError("Cannot find a migration matching '%s' from app '%s'. Is it in INSTALLED_APPS?" % (app_label, migration_name))
+            targets = [(app_label, migration.name)]
+            target_app_labels_only = False
+        elif len(args) == 1:
+            app_label = args[0]
+            if app_label not in executor.loader.migrated_apps:
+                raise CommandError("App '%s' does not have migrations (you cannot selectively sync unmigrated apps)" % app_label)
+            targets = [key for key in executor.loader.graph.leaf_nodes() if key[0] == app_label]
+        else:
+            targets = executor.loader.graph.leaf_nodes()
+            run_syncdb = True
+
         plan = executor.migration_plan(targets)
 
+        # Print some useful info
         if self.verbosity >= 1:
-            self.stdout.write(self.style.MIGRATE_LABEL("  Apps with migrations:    ") + (", ".join(executor.loader.migrated_apps) or "(none)"))
+            self.stdout.write(self.style.MIGRATE_HEADING("Operations to perform:"))
+            if run_syncdb:
+                self.stdout.write(self.style.MIGRATE_LABEL("  Synchronize unmigrated apps: ") + (", ".join(executor.loader.unmigrated_apps) or "(none)"))
+            if target_app_labels_only:
+                self.stdout.write(self.style.MIGRATE_LABEL("  Apply all migrations: ") + (", ".join(set(a for a, n in targets)) or "(none)"))
+            else:
+                if targets[0][1] is None:
+                    self.stdout.write(self.style.MIGRATE_LABEL("  Unapply all migrations: ") + "%s" % (targets[0][0], ))
+                else:
+                    self.stdout.write(self.style.MIGRATE_LABEL("  Target specific migration: ") + "%s, from %s" % (targets[0][1], targets[0][0]))
 
         # Run the syncdb phase.
         # If you ever manage to get rid of this, I owe you many, many drinks.
-        self.stdout.write(self.style.MIGRATE_HEADING("Synchronizing apps without migrations:"))
-        self.sync_apps(connection, executor.loader.unmigrated_apps)
+        if run_syncdb:
+            self.stdout.write(self.style.MIGRATE_HEADING("Synchronizing apps without migrations:"))
+            self.sync_apps(connection, executor.loader.unmigrated_apps)
 
         # Migrate!
         if self.verbosity >= 1:

django/db/migrations/executor.py

@@ -22,9 +22,17 @@ class MigrationExecutor(object):
         plan = []
         applied = self.recorder.applied_migrations()
         for target in targets:
+            # If the target is (appname, None), that means unmigrate everything
+            if target[1] is None:
+                for root in self.loader.graph.root_nodes():
+                    if root[0] == target[0]:
+                        for migration in self.loader.graph.backwards_plan(root):
+                            if migration in applied:
+                                plan.append((self.loader.graph.nodes[migration], True))
+                                applied.remove(migration)
             # If the migration is already applied, do backwards mode,
             # otherwise do forwards mode.
-            if target in applied:
+            elif target in applied:
                 for migration in self.loader.graph.backwards_plan(target)[:-1]:
                     if migration in applied:
                         plan.append((self.loader.graph.nodes[migration], True))

django/db/migrations/loader.py

@@ -79,6 +79,23 @@ class MigrationLoader(object):
                     raise BadMigrationError("Migration %s in app %s has no Migration class" % (migration_name, app_label))
                 self.disk_migrations[app_label, migration_name] = migration_module.Migration(migration_name, app_label)
 
+    def get_migration_by_prefix(self, app_label, name_prefix):
+        "Returns the migration(s) which match the given app label and name _prefix_"
+        # Make sure we have the disk data
+        if self.disk_migrations is None:
+            self.load_disk()
+        # Do the search
+        results = []
+        for l, n in self.disk_migrations:
+            if l == app_label and n.startswith(name_prefix):
+                results.append((l, n))
+        if len(results) > 1:
+            raise AmbiguityError("There is more than one migration for '%s' with the prefix '%s'" % (app_label, name_prefix))
+        elif len(results) == 0:
+            raise KeyError("There no migrations for '%s' with the prefix '%s'" % (app_label, name_prefix))
+        else:
+            return self.disk_migrations[results[0]]
+
     @cached_property
     def graph(self):
         """
@@ -141,3 +158,10 @@ class BadMigrationError(Exception):
     Raised when there's a bad migration (unreadable/bad format/etc.)
     """
     pass
+
+
+class AmbiguityError(Exception):
+    """
+    Raised when more than one migration matches a name prefix
+    """
+    pass

tests/migrations/test_loader.py

@@ -1,7 +1,7 @@
 from django.test import TestCase
 from django.test.utils import override_settings
 from django.db import connection
-from django.db.migrations.loader import MigrationLoader
+from django.db.migrations.loader import MigrationLoader, AmbiguityError
 from django.db.migrations.recorder import MigrationRecorder
 
 
@@ -64,3 +64,16 @@ class LoaderTests(TestCase):
             [x for x, y in book_state.fields],
             ["id", "author"]
         )
+
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
+    def test_name_match(self):
+        "Tests prefix name matching"
+        migration_loader = MigrationLoader(connection)
+        self.assertEqual(
+            migration_loader.get_migration_by_prefix("migrations", "0001").name,
+            "0001_initial",
+        )
+        with self.assertRaises(AmbiguityError):
+            migration_loader.get_migration_by_prefix("migrations", "0")
+        with self.assertRaises(KeyError):
+            migration_loader.get_migration_by_prefix("migrations", "blarg")