Autodetect fields, have migrate actually work

django/core/management/commands/migrate.py

@@ -72,7 +72,7 @@ class Command(NoArgsCommand):
         plan = executor.migration_plan(targets)
 
         if self.verbosity >= 1:
-            self.stdout.write(self.style.MIGRATE_LABEL("  Apps with migrations:    ") + (", ".join(executor.loader.disk_migrations) or "(none)"))
+            self.stdout.write(self.style.MIGRATE_LABEL("  Apps with migrations:    ") + (", ".join(executor.loader.migrated_apps) or "(none)"))
 
         # Run the syncdb phase.
         # If you ever manage to get rid of this, I owe you many, many drinks.

django/db/migrations/autodetector.py

@@ -34,7 +34,7 @@ class MigrationAutodetector(object):
         """
         # We'll store migrations as lists by app names for now
         self.migrations = {}
-        # Stage one: Adding models.
+        # Adding models.
         added_models = set(self.to_state.models.keys()) - set(self.from_state.models.keys())
         for app_label, model_name in added_models:
             model_state = self.to_state.models[app_label, model_name]
@@ -57,6 +57,32 @@ class MigrationAutodetector(object):
                     model_state.name,
                 )
             )
+        # Changes within models
+        kept_models = set(self.from_state.models.keys()).intersection(self.to_state.models.keys())
+        for app_label, model_name in kept_models:
+            old_model_state = self.from_state.models[app_label, model_name]
+            new_model_state = self.to_state.models[app_label, model_name]
+            # New fields
+            old_field_names = set([x for x, y in old_model_state.fields])
+            new_field_names = set([x for x, y in new_model_state.fields])
+            for field_name in new_field_names - old_field_names:
+                self.add_to_migration(
+                    app_label,
+                    operations.AddField(
+                        model_name = model_name,
+                        name = field_name,
+                        field = [y for x, y in new_model_state.fields if x == field_name][0],
+                    )
+                )
+            # Old fields
+            for field_name in old_field_names - new_field_names:
+                self.add_to_migration(
+                    app_label,
+                    operations.RemoveField(
+                        model_name = model_name,
+                        name = field_name,
+                    )
+                )
         # Alright, now add internal dependencies
         for app_label, migrations in self.migrations.items():
             for m1, m2 in zip(migrations, migrations[1:]):

django/db/migrations/loader.py

@@ -50,6 +50,7 @@ class MigrationLoader(object):
         """
         self.disk_migrations = {}
         self.unmigrated_apps = set()
+        self.migrated_apps = set()
         for app in cache.get_apps():
             # Get the migrations module directory
             app_label = app.__name__.split(".")[-2]
@@ -62,6 +63,7 @@ class MigrationLoader(object):
                 if "No module named" in str(e) and "migrations" in str(e):
                     self.unmigrated_apps.add(app_label)
                     continue
+            self.migrated_apps.add(app_label)
             directory = os.path.dirname(module.__file__)
             # Scan for .py[c|o] files
             migration_names = set()

django/db/migrations/operations/fields.py

@@ -6,13 +6,13 @@ class AddField(Operation):
     Adds a field to a model.
     """
 
-    def __init__(self, model_name, name, instance):
+    def __init__(self, model_name, name, field):
         self.model_name = model_name
         self.name = name
-        self.instance = instance
+        self.field = field
 
     def state_forwards(self, app_label, state):
-        state.models[app_label, self.model_name.lower()].fields.append((self.name, self.instance))
+        state.models[app_label, self.model_name.lower()].fields.append((self.name, self.field))
 
     def database_forwards(self, app_label, schema_editor, from_state, to_state):
         from_model = from_state.render().get_model(app_label, self.model_name)