Allowed RemoveField operations to be optimized through.

3 files changed, 19 insertions, 39 deletions

diff --git a/django/db/migrations/operations/fields.py b/django/db/migrations/operations/fields.py
index 9faeb81318..601f9ac43a 100644
--- a/django/db/migrations/operations/fields.py
+++ b/django/db/migrations/operations/fields.py
@@ -34,9 +34,7 @@ class FieldOperation(Operation):
             return True
         if self.field:
             return field_references_model(self.field, ModelTuple(app_label, name_lower))
-        # Refuse the temptation to guess. This operation could be performed on
-        # a field referencing the specified model.
-        return True
+        return False
 
     def references_field(self, model_name, name, app_label=None):
         model_name_lower = model_name.lower()
@@ -60,10 +58,7 @@ class FieldOperation(Operation):
                         (getattr(remote_field, 'through_fields', None) is None or
                             name in remote_field.through_fields)):
                     return True
-            return False
-        # Refuse the temptation to guess. This operation could be performed on
-        # a field referencing the specified model.
-        return True
+        return False
 
     def reduce(self, operation, in_between, app_label=None):
         return (
diff --git a/tests/migrations/test_autodetector.py b/tests/migrations/test_autodetector.py
index 34c9dac989..e3ce3a129a 100644
--- a/tests/migrations/test_autodetector.py
+++ b/tests/migrations/test_autodetector.py
@@ -1925,11 +1925,9 @@ class AutodetectorTests(TestCase):
         # Remove both the through model and ManyToMany
         # Right number/type of migrations?
         self.assertNumberMigrations(changes, "otherapp", 1)
-        self.assertOperationTypes(changes, "otherapp", 0, ["RemoveField", "RemoveField", "RemoveField", "DeleteModel"])
-        self.assertOperationAttributes(changes, 'otherapp', 0, 0, name="author", model_name='attribution')
-        self.assertOperationAttributes(changes, 'otherapp', 0, 1, name="book", model_name='attribution')
-        self.assertOperationAttributes(changes, 'otherapp', 0, 2, name="authors", model_name='book')
-        self.assertOperationAttributes(changes, 'otherapp', 0, 3, name='Attribution')
+        self.assertOperationTypes(changes, 'otherapp', 0, ['RemoveField', 'DeleteModel'])
+        self.assertOperationAttributes(changes, 'otherapp', 0, 0, name='authors', model_name='book')
+        self.assertOperationAttributes(changes, 'otherapp', 0, 1, name='Attribution')
 
     def test_many_to_many_removed_before_through_model_2(self):
         """
@@ -1944,14 +1942,10 @@ class AutodetectorTests(TestCase):
         # Remove both the through model and ManyToMany
         # Right number/type of migrations?
         self.assertNumberMigrations(changes, "otherapp", 1)
-        self.assertOperationTypes(changes, "otherapp", 0, [
-            "RemoveField", "RemoveField", "RemoveField", "DeleteModel", "DeleteModel"
-        ])
-        self.assertOperationAttributes(changes, 'otherapp', 0, 0, name="author", model_name='attribution')
-        self.assertOperationAttributes(changes, 'otherapp', 0, 1, name="book", model_name='attribution')
-        self.assertOperationAttributes(changes, 'otherapp', 0, 2, name="authors", model_name='book')
-        self.assertOperationAttributes(changes, 'otherapp', 0, 3, name='Attribution')
-        self.assertOperationAttributes(changes, 'otherapp', 0, 4, name='Book')
+        self.assertOperationTypes(changes, 'otherapp', 0, ['RemoveField', 'DeleteModel', 'DeleteModel'])
+        self.assertOperationAttributes(changes, 'otherapp', 0, 0, name='authors', model_name='book')
+        self.assertOperationAttributes(changes, 'otherapp', 0, 1, name='Attribution')
+        self.assertOperationAttributes(changes, 'otherapp', 0, 2, name='Book')
 
     def test_m2m_w_through_multistep_remove(self):
         """
@@ -1964,13 +1958,12 @@ class AutodetectorTests(TestCase):
         # Right number/type of migrations?
         self.assertNumberMigrations(changes, "testapp", 1)
         self.assertOperationTypes(changes, "testapp", 0, [
-            "RemoveField", "RemoveField", "RemoveField", "DeleteModel", "DeleteModel"
+            "RemoveField", "RemoveField", "DeleteModel", "DeleteModel"
         ])
-        self.assertOperationAttributes(changes, "testapp", 0, 0, name="publishers", model_name='author')
-        self.assertOperationAttributes(changes, "testapp", 0, 1, name="author", model_name='contract')
-        self.assertOperationAttributes(changes, "testapp", 0, 2, name="publisher", model_name='contract')
-        self.assertOperationAttributes(changes, "testapp", 0, 3, name="Author")
-        self.assertOperationAttributes(changes, "testapp", 0, 4, name="Contract")
+        self.assertOperationAttributes(changes, "testapp", 0, 0, name="author", model_name='contract')
+        self.assertOperationAttributes(changes, "testapp", 0, 1, name="publisher", model_name='contract')
+        self.assertOperationAttributes(changes, "testapp", 0, 2, name="Author")
+        self.assertOperationAttributes(changes, "testapp", 0, 3, name="Contract")
 
     def test_concrete_field_changed_to_many_to_many(self):
         """
@@ -2007,11 +2000,10 @@ class AutodetectorTests(TestCase):
         changes = self.get_changes([self.author_with_publisher, self.publisher_with_author], [])
         # Right number/type of migrations?
         self.assertNumberMigrations(changes, "testapp", 1)
-        self.assertOperationTypes(changes, "testapp", 0, ["RemoveField", "RemoveField", "DeleteModel", "DeleteModel"])
-        self.assertOperationAttributes(changes, "testapp", 0, 0, name="publisher", model_name='author')
-        self.assertOperationAttributes(changes, "testapp", 0, 1, name="author", model_name='publisher')
-        self.assertOperationAttributes(changes, "testapp", 0, 2, name="Author")
-        self.assertOperationAttributes(changes, "testapp", 0, 3, name="Publisher")
+        self.assertOperationTypes(changes, "testapp", 0, ["RemoveField", "DeleteModel", "DeleteModel"])
+        self.assertOperationAttributes(changes, "testapp", 0, 0, name="author", model_name='publisher')
+        self.assertOperationAttributes(changes, "testapp", 0, 1, name="Author")
+        self.assertOperationAttributes(changes, "testapp", 0, 2, name="Publisher")
 
     def test_alter_model_options(self):
         """Changing a model's options should make a change."""
diff --git a/tests/migrations/test_operations.py b/tests/migrations/test_operations.py
index 5dfe4acb4d..142330127b 100644
--- a/tests/migrations/test_operations.py
+++ b/tests/migrations/test_operations.py
@@ -2758,10 +2758,7 @@ class TestCreateModel(SimpleTestCase):
 
 class FieldOperationTests(SimpleTestCase):
     def test_references_model(self):
-        operation = FieldOperation('MoDel', 'field')
-        # When missing a field declaration always assume it's referencing.
-        self.assertIs(operation.references_model('Whatever'), True)
-        operation.field = models.ForeignKey('Other', models.CASCADE)
+        operation = FieldOperation('MoDel', 'field', models.ForeignKey('Other', models.CASCADE))
         # Model name match.
         self.assertIs(operation.references_model('mOdEl'), True)
         # Referenced field.
@@ -2769,10 +2766,6 @@ class FieldOperationTests(SimpleTestCase):
         # Doesn't reference.
         self.assertIs(operation.references_model('Whatever'), False)
 
-    def test_references_field_missing_field(self):
-        operation = FieldOperation('MoDel', 'field')
-        self.assertIs(operation.references_field('Whatever', 'missing'), True)
-
     def test_references_field_by_name(self):
         operation = FieldOperation('MoDel', 'field', models.BooleanField(default=False))
         self.assertIs(operation.references_field('model', 'field'), True)