Fixed #24123 -- Used all available migrations to generate the initial migration state

Thanks Collin Anderson for the input when creating the patch and Tim Graham for the review.

django/db/migrations/executor.py

@@ -4,6 +4,7 @@ from django.db import migrations
 from django.apps.registry import apps as global_apps
 from .loader import MigrationLoader
 from .recorder import MigrationRecorder
+from .state import ProjectState
 
 
 class MigrationExecutor(object):
@@ -18,11 +19,14 @@ class MigrationExecutor(object):
         self.recorder = MigrationRecorder(self.connection)
         self.progress_callback = progress_callback
 
-    def migration_plan(self, targets):
+    def migration_plan(self, targets, clean_start=False):
         """
         Given a set of targets, returns a list of (Migration instance, backwards?).
         """
         plan = []
+        if clean_start:
+            applied = set()
+        else:
             applied = set(self.loader.applied_migrations)
         for target in targets:
             # If the target is (app_label, None), that means unmigrate everything
@@ -60,17 +64,31 @@ class MigrationExecutor(object):
     def migrate(self, targets, plan=None, fake=False):
         """
         Migrates the database up to the given targets.
+
+        Django first needs to create all project states before a migration is
+        (un)applied and in a second step run all the database operations.
         """
         if plan is None:
             plan = self.migration_plan(targets)
-        state = None
+        migrations_to_run = {m[0] for m in plan}
+        # Create the forwards plan Django would follow on an empty database
+        full_plan = self.migration_plan(self.loader.graph.leaf_nodes(), clean_start=True)
+        # Holds all states right before and right after a migration is applied
+        # if the migration is being run.
+        states = {}
+        state = ProjectState(real_apps=list(self.loader.unmigrated_apps))
+        state.apps  # Render all real_apps -- performance critical
+        # Phase 1 -- Store all required states
+        for migration, _ in full_plan:
+            if migration in migrations_to_run:
+                states[migration] = state.clone()
+            state = migration.mutate_state(state)  # state is cloned inside
+        # Phase 2 -- Run the migrations
         for migration, backwards in plan:
-            if state is None:
-                state = self.loader.project_state((migration.app_label, migration.name), at_end=False)
             if not backwards:
-                state = self.apply_migration(state, migration, fake=fake)
+                self.apply_migration(states[migration], migration, fake=fake)
             else:
-                state = self.unapply_migration(state, migration, fake=fake)
+                self.unapply_migration(states[migration], migration, fake=fake)
 
     def collect_sql(self, plan):
         """

tests/migrations/migrations_test_apps/lookuperror_a/migrations/0001_initial.py

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='A1',
+            fields=[
+                ('id', models.AutoField(serialize=False, verbose_name='ID', auto_created=True, primary_key=True)),
+            ],
+        ),
+    ]

tests/migrations/migrations_test_apps/lookuperror_a/migrations/0002_a2.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('lookuperror_a', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='A2',
+            fields=[
+                ('id', models.AutoField(verbose_name='ID', primary_key=True, serialize=False, auto_created=True)),
+            ],
+        ),
+    ]

tests/migrations/migrations_test_apps/lookuperror_a/migrations/0003_a3.py

@@ -0,0 +1,24 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('lookuperror_c', '0002_c2'),
+        ('lookuperror_b', '0002_b2'),
+        ('lookuperror_a', '0002_a2'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='A3',
+            fields=[
+                ('id', models.AutoField(serialize=False, auto_created=True, primary_key=True, verbose_name='ID')),
+                ('b2', models.ForeignKey(to='lookuperror_b.B2')),
+                ('c2', models.ForeignKey(to='lookuperror_c.C2')),
+            ],
+        ),
+    ]

tests/migrations/migrations_test_apps/lookuperror_a/migrations/0004_a4.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('lookuperror_a', '0003_a3'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='A4',
+            fields=[
+                ('id', models.AutoField(auto_created=True, serialize=False, verbose_name='ID', primary_key=True)),
+            ],
+        ),
+    ]

tests/migrations/migrations_test_apps/lookuperror_a/models.py

@@ -0,0 +1,18 @@
+from django.db import models
+
+
+class A1(models.Model):
+    pass
+
+
+class A2(models.Model):
+    pass
+
+
+class A3(models.Model):
+    b2 = models.ForeignKey('lookuperror_b.B2')
+    c2 = models.ForeignKey('lookuperror_c.C2')
+
+
+class A4(models.Model):
+    pass

tests/migrations/migrations_test_apps/lookuperror_b/migrations/0001_initial.py

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='B1',
+            fields=[
+                ('id', models.AutoField(serialize=False, auto_created=True, primary_key=True, verbose_name='ID')),
+            ],
+        ),
+    ]

tests/migrations/migrations_test_apps/lookuperror_b/migrations/0002_b2.py

@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('lookuperror_a', '0002_a2'),
+        ('lookuperror_b', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='B2',
+            fields=[
+                ('id', models.AutoField(primary_key=True, verbose_name='ID', auto_created=True, serialize=False)),
+                ('a1', models.ForeignKey(to='lookuperror_a.A1')),
+            ],
+        ),
+    ]

tests/migrations/migrations_test_apps/lookuperror_b/migrations/0003_b3.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('lookuperror_b', '0002_b2'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='B3',
+            fields=[
+                ('id', models.AutoField(verbose_name='ID', serialize=False, primary_key=True, auto_created=True)),
+            ],
+        ),
+    ]

tests/migrations/migrations_test_apps/lookuperror_b/models.py

@@ -0,0 +1,13 @@
+from django.db import models
+
+
+class B1(models.Model):
+    pass
+
+
+class B2(models.Model):
+    a1 = models.ForeignKey('lookuperror_a.A1')
+
+
+class B3(models.Model):
+    pass

tests/migrations/migrations_test_apps/lookuperror_c/migrations/0001_initial.py

@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='C1',
+            fields=[
+                ('id', models.AutoField(serialize=False, verbose_name='ID', auto_created=True, primary_key=True)),
+            ],
+        ),
+    ]

tests/migrations/migrations_test_apps/lookuperror_c/migrations/0002_c2.py

@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('lookuperror_a', '0002_a2'),
+        ('lookuperror_c', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='C2',
+            fields=[
+                ('id', models.AutoField(auto_created=True, verbose_name='ID', primary_key=True, serialize=False)),
+                ('a1', models.ForeignKey(to='lookuperror_a.A1')),
+            ],
+        ),
+    ]

tests/migrations/migrations_test_apps/lookuperror_c/migrations/0003_c3.py

@@ -0,0 +1,20 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import models, migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('lookuperror_c', '0002_c2'),
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='C3',
+            fields=[
+                ('id', models.AutoField(auto_created=True, serialize=False, verbose_name='ID', primary_key=True)),
+            ],
+        ),
+    ]

tests/migrations/migrations_test_apps/lookuperror_c/models.py

@@ -0,0 +1,13 @@
+from django.db import models
+
+
+class C1(models.Model):
+    pass
+
+
+class C2(models.Model):
+    a1 = models.ForeignKey('lookuperror_a.A1')
+
+
+class C3(models.Model):
+    pass

tests/migrations/test_executor.py

@@ -233,6 +233,96 @@ class ExecutorTests(MigrationTestBase):
         self.assertTableNotExists("migrations_author")
         self.assertTableNotExists("migrations_tribble")
 
+    @override_settings(
+        INSTALLED_APPS=[
+            "migrations.migrations_test_apps.lookuperror_a",
+            "migrations.migrations_test_apps.lookuperror_b",
+            "migrations.migrations_test_apps.lookuperror_c"
+        ]
+    )
+    def test_unrelated_model_lookups_forwards(self):
+        """
+        #24123 - Tests that all models of apps already applied which are
+        unrelated to the first app being applied are part of the initial model
+        state.
+        """
+        try:
+            executor = MigrationExecutor(connection)
+            self.assertTableNotExists("lookuperror_a_a1")
+            self.assertTableNotExists("lookuperror_b_b1")
+            self.assertTableNotExists("lookuperror_c_c1")
+            executor.migrate([("lookuperror_b", "0003_b3")])
+            self.assertTableExists("lookuperror_b_b3")
+            # Rebuild the graph to reflect the new DB state
+            executor.loader.build_graph()
+
+            # Migrate forwards -- This led to a lookup LookupErrors because
+            # lookuperror_b.B2 is already applied
+            executor.migrate([
+                ("lookuperror_a", "0004_a4"),
+                ("lookuperror_c", "0003_c3"),
+            ])
+            self.assertTableExists("lookuperror_a_a4")
+            self.assertTableExists("lookuperror_c_c3")
+
+            # Rebuild the graph to reflect the new DB state
+            executor.loader.build_graph()
+        finally:
+            # Cleanup
+            executor.migrate([
+                ("lookuperror_a", None),
+                ("lookuperror_b", None),
+                ("lookuperror_c", None),
+            ])
+            self.assertTableNotExists("lookuperror_a_a1")
+            self.assertTableNotExists("lookuperror_b_b1")
+            self.assertTableNotExists("lookuperror_c_c1")
+
+    @override_settings(
+        INSTALLED_APPS=[
+            "migrations.migrations_test_apps.lookuperror_a",
+            "migrations.migrations_test_apps.lookuperror_b",
+            "migrations.migrations_test_apps.lookuperror_c"
+        ]
+    )
+    def test_unrelated_model_lookups_backwards(self):
+        """
+        #24123 - Tests that all models of apps being unapplied which are
+        unrelated to the first app being unapplied are part of the initial
+        model state.
+        """
+        try:
+            executor = MigrationExecutor(connection)
+            self.assertTableNotExists("lookuperror_a_a1")
+            self.assertTableNotExists("lookuperror_b_b1")
+            self.assertTableNotExists("lookuperror_c_c1")
+            executor.migrate([
+                ("lookuperror_a", "0004_a4"),
+                ("lookuperror_b", "0003_b3"),
+                ("lookuperror_c", "0003_c3"),
+            ])
+            self.assertTableExists("lookuperror_b_b3")
+            self.assertTableExists("lookuperror_a_a4")
+            self.assertTableExists("lookuperror_c_c3")
+            # Rebuild the graph to reflect the new DB state
+            executor.loader.build_graph()
+
+            # Migrate backwards -- This led to a lookup LookupErrors because
+            # lookuperror_b.B2 is not in the initial state (unrelated to app c)
+            executor.migrate([("lookuperror_a", None)])
+
+            # Rebuild the graph to reflect the new DB state
+            executor.loader.build_graph()
+        finally:
+            # Cleanup
+            executor.migrate([
+                ("lookuperror_b", None),
+                ("lookuperror_c", None)
+            ])
+            self.assertTableNotExists("lookuperror_a_a1")
+            self.assertTableNotExists("lookuperror_b_b1")
+            self.assertTableNotExists("lookuperror_c_c1")
+
 
 class FakeLoader(object):
     def __init__(self, graph, applied):