Fixed #29808 -- Fixed initial migration detection when identifiers are case-insensitive.

Thanks Simon Charette for the review.

django/db/migrations/executor.py

@@ -329,8 +329,11 @@ class MigrationExecutor:
         apps = after_state.apps
         found_create_model_migration = False
         found_add_field_migration = False
+        fold_identifier_case = self.connection.features.ignores_table_name_case
         with self.connection.cursor() as cursor:
             existing_table_names = set(self.connection.introspection.table_names(cursor))
+            if fold_identifier_case:
+                existing_table_names = {name.casefold() for name in existing_table_names}
         # Make sure all create model and add field operations are done
         for operation in migration.operations:
             if isinstance(operation, migrations.CreateModel):
@@ -341,7 +344,10 @@ class MigrationExecutor:
                     model = global_apps.get_model(model._meta.swapped)
                 if should_skip_detecting_model(migration, model):
                     continue
-                if model._meta.db_table not in existing_table_names:
+                db_table = model._meta.db_table
+                if fold_identifier_case:
+                    db_table = db_table.casefold()
+                if db_table not in existing_table_names:
                     return False, project_state
                 found_create_model_migration = True
             elif isinstance(operation, migrations.AddField):
@@ -358,7 +364,10 @@ class MigrationExecutor:
 
                 # Handle implicit many-to-many tables created by AddField.
                 if field.many_to_many:
-                    if field.remote_field.through._meta.db_table not in existing_table_names:
+                    through_db_table = field.remote_field.through._meta.db_table
+                    if fold_identifier_case:
+                        through_db_table = through_db_table.casefold()
+                    if through_db_table not in existing_table_names:
                         return False, project_state
                     else:
                         found_add_field_migration = True
@@ -368,7 +377,12 @@ class MigrationExecutor:
                     table,
                 )
                 for column in columns:
-                    if column.name == field.column:
+                    field_column = field.column
+                    column_name = column.name
+                    if fold_identifier_case:
+                        column_name = column_name.casefold()
+                        field_column = field_column.casefold()
+                    if column_name == field_column:
                         found_add_field_migration = True
                         break
                 else:

tests/migrations/test_commands.py

@@ -14,7 +14,7 @@ from django.db.backends.base.schema import BaseDatabaseSchemaEditor
 from django.db.backends.utils import truncate_name
 from django.db.migrations.exceptions import InconsistentMigrationHistory
 from django.db.migrations.recorder import MigrationRecorder
-from django.test import TestCase, override_settings
+from django.test import TestCase, override_settings, skipUnlessDBFeature
 
 from .models import UnicodeModel, UnserializableModel
 from .routers import TestRouter
@@ -197,6 +197,32 @@ class MigrateTests(MigrationTestBase):
             self.assertTableNotExists("migrations_tribble", using=db)
             self.assertTableNotExists("migrations_book", using=db)
 
+    @skipUnlessDBFeature('ignores_table_name_case')
+    def test_migrate_fake_initial_case_insensitive(self):
+        with override_settings(MIGRATION_MODULES={
+            'migrations': 'migrations.test_fake_initial_case_insensitive.initial',
+        }):
+            call_command('migrate', 'migrations', '0001', verbosity=0)
+            call_command('migrate', 'migrations', 'zero', fake=True, verbosity=0)
+
+        with override_settings(MIGRATION_MODULES={
+            'migrations': 'migrations.test_fake_initial_case_insensitive.fake_initial',
+        }):
+            out = io.StringIO()
+            call_command(
+                'migrate',
+                'migrations',
+                '0001',
+                fake_initial=True,
+                stdout=out,
+                verbosity=1,
+                no_color=True,
+            )
+            self.assertIn(
+                'migrations.0001_initial... faked',
+                out.getvalue().lower(),
+            )
+
     @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_fake_split_initial"})
     def test_migrate_fake_split_initial(self):
         """

tests/migrations/test_fake_initial_case_insensitive/fake_initial/0001_initial.py

@@ -0,0 +1,28 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    initial = True
+
+    operations = [
+        migrations.CreateModel(
+            'fakeinitialmodel',
+            [
+                ('id', models.AutoField(primary_key=True)),
+                ('field', models.CharField(max_length=20)),
+            ],
+            options={
+                'db_table': 'migrations_mIxEd_cAsE_iNiTiAl_mOdEl',
+            },
+        ),
+        migrations.AddField(
+            model_name='fakeinitialmodel',
+            name='field_mixed_case',
+            field=models.CharField(max_length=20, db_column='fIeLd_mIxEd_cAsE'),
+        ),
+        migrations.AddField(
+            model_name='fakeinitialmodel',
+            name='fake_initial_model',
+            field=models.ManyToManyField(to='migrations.fakeinitialmodel', db_table='m2m_mIxEd_cAsE'),
+        ),
+    ]

tests/migrations/test_fake_initial_case_insensitive/initial/0001_initial.py

@@ -0,0 +1,23 @@
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+    initial = True
+
+    operations = [
+        migrations.CreateModel(
+            name='fakeinitialmodel',
+            fields=[
+                ('id', models.AutoField(primary_key=True)),
+                ('field', models.CharField(max_length=20)),
+                ('field_mixed_case', models.CharField(max_length=20, db_column='FiEld_MiXeD_CaSe')),
+                (
+                    'fake_initial_mode',
+                    models.ManyToManyField('migrations.FakeInitialModel', db_table='m2m_MiXeD_CaSe'),
+                ),
+            ],
+            options={
+                'db_table': 'migrations_MiXeD_CaSe_InItIaL_MoDel',
+            },
+        ),
+    ]