Fixed #24129 -- Added indicator that migrations are rendering the initial state

Thanks Tim Graham for the review.

django/core/management/commands/migrate.py

@@ -216,7 +216,7 @@ class Command(BaseCommand):
         # to do at this point.
         emit_post_migrate_signal(created_models, self.verbosity, self.interactive, connection.alias)
 
-    def migration_progress_callback(self, action, migration, fake=False):
+    def migration_progress_callback(self, action, migration=None, fake=False):
         if self.verbosity >= 1:
             compute_time = self.verbosity > 1
             if action == "apply_start":
@@ -241,6 +241,14 @@ class Command(BaseCommand):
                     self.stdout.write(self.style.MIGRATE_SUCCESS(" FAKED" + elapsed))
                 else:
                     self.stdout.write(self.style.MIGRATE_SUCCESS(" OK" + elapsed))
+            elif action == "render_start":
+                if compute_time:
+                    self.start = time.time()
+                self.stdout.write("  Rendering model states...", ending="")
+                self.stdout.flush()
+            elif action == "render_success":
+                elapsed = " (%.3fs)" % (time.time() - self.start) if compute_time else ""
+                self.stdout.write(self.style.MIGRATE_SUCCESS(" DONE" + elapsed))
 
     def sync_apps(self, connection, app_labels):
         "Runs the old syncdb-style operation on a list of app_labels."

django/db/migrations/executor.py

@@ -77,7 +77,11 @@ class MigrationExecutor(object):
         # if the migration is being run.
         states = {}
         state = ProjectState(real_apps=list(self.loader.unmigrated_apps))
+        if self.progress_callback:
+            self.progress_callback("render_start")
         state.apps  # Render all real_apps -- performance critical
+        if self.progress_callback:
+            self.progress_callback("render_success")
         # Phase 1 -- Store all required states
         for migration, _ in full_plan:
             if migration in migrations_to_run:

tests/migrations/test_executor.py

@@ -150,7 +150,7 @@ class ExecutorTests(MigrationTestBase):
         """
         state = {"faked": None}
 
-        def fake_storer(phase, migration, fake):
+        def fake_storer(phase, migration=None, fake=None):
             state["faked"] = fake
         executor = MigrationExecutor(connection, progress_callback=fake_storer)
         # Were the tables there before?
@@ -323,6 +323,51 @@ class ExecutorTests(MigrationTestBase):
             self.assertTableNotExists("lookuperror_b_b1")
             self.assertTableNotExists("lookuperror_c_c1")
 
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations"})
+    def test_process_callback(self):
+        """
+        #24129 - Tests callback process
+        """
+        call_args_list = []
+
+        def callback(*args):
+            call_args_list.append(args)
+
+        executor = MigrationExecutor(connection, progress_callback=callback)
+        # Were the tables there before?
+        self.assertTableNotExists("migrations_author")
+        self.assertTableNotExists("migrations_tribble")
+        executor.migrate([
+            ("migrations", "0001_initial"),
+            ("migrations", "0002_second"),
+        ])
+        # Rebuild the graph to reflect the new DB state
+        executor.loader.build_graph()
+
+        executor.migrate([
+            ("migrations", None),
+            ("migrations", None),
+        ])
+        self.assertTableNotExists("migrations_author")
+        self.assertTableNotExists("migrations_tribble")
+
+        migrations = executor.loader.graph.nodes
+        expected = [
+            ("render_start", ),
+            ("render_success", ),
+            ("apply_start", migrations['migrations', '0001_initial'], False),
+            ("apply_success", migrations['migrations', '0001_initial'], False),
+            ("apply_start", migrations['migrations', '0002_second'], False),
+            ("apply_success", migrations['migrations', '0002_second'], False),
+            ("render_start", ),
+            ("render_success", ),
+            ("unapply_start", migrations['migrations', '0002_second'], False),
+            ("unapply_success", migrations['migrations', '0002_second'], False),
+            ("unapply_start", migrations['migrations', '0001_initial'], False),
+            ("unapply_success", migrations['migrations', '0001_initial'], False),
+        ]
+        self.assertEqual(call_args_list, expected)
+
 
 class FakeLoader(object):
     def __init__(self, graph, applied):