[1.11.x] Fixed #28305 -- Fixed "Cannot change column 'x': used in a foreign key constraint" crash on MySQL with a sequence of AlterField or RenameField operations.

Regression in 45ded053b1f4320284aa5dac63052f6d1baefea9.

Backport of c3e0adcad8d8ba94b33cabd137056166ed36dae0 from master

1 files changed, 77 insertions, 0 deletions

diff --git a/tests/migrations/test_operations.py b/tests/migrations/test_operations.py
index 64ae395d94..0899e92a3d 100644
--- a/tests/migrations/test_operations.py
+++ b/tests/migrations/test_operations.py
@@ -1324,6 +1324,83 @@ class OperationTests(OperationTestBase):
             operation.database_backwards("test_alflpkfk", editor, new_state, project_state)
         assertIdTypeEqualsFkType()
 
+    def test_alter_field_reloads_state_on_fk_target_changes(self):
+        """
+        If AlterField doesn't reload state appropriately, the second AlterField
+        crashes on MySQL due to not dropping the PonyRider.pony foreign key
+        constraint before modifying the column.
+        """
+        app_label = 'alter_alter_field_reloads_state_on_fk_target_changes'
+        project_state = self.apply_operations(app_label, ProjectState(), operations=[
+            migrations.CreateModel('Rider', fields=[
+                ('id', models.CharField(primary_key=True, max_length=100)),
+            ]),
+            migrations.CreateModel('Pony', fields=[
+                ('id', models.CharField(primary_key=True, max_length=100)),
+                ('rider', models.ForeignKey('%s.Rider' % app_label, models.CASCADE)),
+            ]),
+            migrations.CreateModel('PonyRider', fields=[
+                ('id', models.AutoField(primary_key=True)),
+                ('pony', models.ForeignKey('%s.Pony' % app_label, models.CASCADE)),
+            ]),
+        ])
+        project_state = self.apply_operations(app_label, project_state, operations=[
+            migrations.AlterField('Rider', 'id', models.CharField(primary_key=True, max_length=99)),
+            migrations.AlterField('Pony', 'id', models.CharField(primary_key=True, max_length=99)),
+        ])
+
+    def test_alter_field_reloads_state_on_fk_with_to_field_target_changes(self):
+        """
+        If AlterField doesn't reload state appropriately, the second AlterField
+        crashes on MySQL due to not dropping the PonyRider.pony foreign key
+        constraint before modifying the column.
+        """
+        app_label = 'alter_alter_field_reloads_state_on_fk_with_to_field_target_changes'
+        project_state = self.apply_operations(app_label, ProjectState(), operations=[
+            migrations.CreateModel('Rider', fields=[
+                ('id', models.CharField(primary_key=True, max_length=100)),
+                ('slug', models.CharField(unique=True, max_length=100)),
+            ]),
+            migrations.CreateModel('Pony', fields=[
+                ('id', models.CharField(primary_key=True, max_length=100)),
+                ('rider', models.ForeignKey('%s.Rider' % app_label, models.CASCADE, to_field='slug')),
+                ('slug', models.CharField(unique=True, max_length=100)),
+            ]),
+            migrations.CreateModel('PonyRider', fields=[
+                ('id', models.AutoField(primary_key=True)),
+                ('pony', models.ForeignKey('%s.Pony' % app_label, models.CASCADE, to_field='slug')),
+            ]),
+        ])
+        project_state = self.apply_operations(app_label, project_state, operations=[
+            migrations.AlterField('Rider', 'slug', models.CharField(unique=True, max_length=99)),
+            migrations.AlterField('Pony', 'slug', models.CharField(unique=True, max_length=99)),
+        ])
+
+    def test_rename_field_reloads_state_on_fk_target_changes(self):
+        """
+        If RenameField doesn't reload state appropriately, the AlterField
+        crashes on MySQL due to not dropping the PonyRider.pony foreign key
+        constraint before modifying the column.
+        """
+        app_label = 'alter_rename_field_reloads_state_on_fk_target_changes'
+        project_state = self.apply_operations(app_label, ProjectState(), operations=[
+            migrations.CreateModel('Rider', fields=[
+                ('id', models.CharField(primary_key=True, max_length=100)),
+            ]),
+            migrations.CreateModel('Pony', fields=[
+                ('id', models.CharField(primary_key=True, max_length=100)),
+                ('rider', models.ForeignKey('%s.Rider' % app_label, models.CASCADE)),
+            ]),
+            migrations.CreateModel('PonyRider', fields=[
+                ('id', models.AutoField(primary_key=True)),
+                ('pony', models.ForeignKey('%s.Pony' % app_label, models.CASCADE)),
+            ]),
+        ])
+        project_state = self.apply_operations(app_label, project_state, operations=[
+            migrations.RenameField('Rider', 'id', 'id2'),
+            migrations.AlterField('Pony', 'id', models.CharField(primary_key=True, max_length=99)),
+        ])
+
     def test_rename_field(self):
         """
         Tests the RenameField operation.