Ticket #23405: ticket_23405_for_1_7.patch

django/db/migrations/autodetector.py

@@ -794 +794 @@
                         None,
                         True
                     ))
-            # You can't just add NOT NULL fields with no default
-            if not field.null and not field.has_default() and not isinstance(field, models.ManyToManyField):
+            # You can't just add NOT NULL fields with no default or fields,
+            # which are not allowing empty strings as default.
+            if (not field.null and not field.has_default()
+               and not isinstance(field, models.ManyToManyField) and not
+               (field.blank and field.empty_strings_allowed)):
                 field = field.clone()
                 field.default = self.questioner.ask_not_null_addition(field_name, model_name)
                 self.add_operation(

docs/releases/1.7.2.txt

@@ -121 +121 @@
   model (:ticket:`23956`).
 
 * Fixed a crash when a ``MultiValueField`` has invalid data (:ticket:`23674`).
+
+* ``makemigrations`` no longer prompts for a default value when adding
+  ``TextField()`` or ``CharField()`` without a default (:ticket:`23405`).

tests/migrations/test_autodetector.py

@@ -62 +62 @@
         ("name", models.CharField(max_length=200, default=models.IntegerField())),
     ])
     author_custom_pk = ModelState("testapp", "Author", [("pk_field", models.IntegerField(primary_key=True))])
+    author_with_biography_non_blank = ModelState("testapp", "Author", [
+        ("id", models.AutoField(primary_key=True)),
+        ("name", models.CharField()),
+        ("biography", models.TextField()),
+    ])
+    author_with_biography_blank = ModelState("testapp", "Author", [
+        ("id", models.AutoField(primary_key=True)),
+        ("name", models.CharField(blank=True)),
+        ("biography", models.TextField(blank=True)),
+    ])
     author_with_book = ModelState("testapp", "Author", [
         ("id", models.AutoField(primary_key=True)),
         ("name", models.CharField(max_length=200)),
@@ -1682 +1692 @@
         self.assertNumberMigrations(changes, 'a', 1)
         self.assertOperationTypes(changes, 'a', 0, ["CreateModel"])
         self.assertMigrationDependencies(changes, 'a', 0, [])
+
+    def test_add_blank_textfield_and_charfield(self):
+        """
+        #23405 - Adding a NOT NULL and blank `CharField` or `TextField`
+        without default should not prompt for a default.
+        """
+        class CustomQuestioner(MigrationQuestioner):
+            def ask_not_null_addition(self, field_name, model_name):
+                raise Exception("Should not have prompted for not null addition")
+
+        before = self.make_project_state([self.author_empty])
+        after = self.make_project_state([self.author_with_biography_blank])
+        autodetector = MigrationAutodetector(before, after, CustomQuestioner())
+        changes = autodetector._detect_changes()
+        self.assertNumberMigrations(changes, 'testapp', 1)
+        self.assertOperationTypes(changes, 'testapp', 0, ["AddField", "AddField"])
+        self.assertOperationAttributes(changes, 'testapp', 0, 0)
+
+    def test_add_non_blank_textfield_and_charfield(self):
+        """
+        #23405 - Adding a NOT NULL and non-blank `CharField` or `TextField`
+        without default should prompt for a default.
+        """
+        class CustomQuestioner(MigrationQuestioner):
+            def __init__(self):
+                super(CustomQuestioner, self).__init__()
+                self.ask_method_call_count = 0
+
+            def ask_not_null_addition(self, field_name, model_name):
+                self.ask_method_call_count += 1
+
+        before = self.make_project_state([self.author_empty])
+        after = self.make_project_state([self.author_with_biography_non_blank])
+        questioner_instance = CustomQuestioner()
+        autodetector = MigrationAutodetector(before, after, questioner_instance)
+        changes = autodetector._detect_changes()
+        # need to check for questioner call count
+        self.assertEqual(questioner_instance.ask_method_call_count, 2)
+        self.assertNumberMigrations(changes, 'testapp', 1)
+        self.assertOperationTypes(changes, 'testapp', 0, ["AddField", "AddField"])
+        self.assertOperationAttributes(changes, 'testapp', 0, 0)