Fixed #31468 -- Allowed specifying migration filename in Operation.

This adds also suggested filename for many built-in operations.

django/db/migrations/autodetector.py

@@ -1313,19 +1313,14 @@ class MigrationAutodetector:
         represent. Names are not guaranteed to be unique, but put some effort
         into the fallback name to avoid VCS conflicts if possible.
         """
+        name = None
         if len(ops) == 1:
-            if isinstance(ops[0], operations.CreateModel):
-                return ops[0].name_lower
-            elif isinstance(ops[0], operations.DeleteModel):
-                return "delete_%s" % ops[0].name_lower
-            elif isinstance(ops[0], operations.AddField):
-                return "%s_%s" % (ops[0].model_name_lower, ops[0].name_lower)
-            elif isinstance(ops[0], operations.RemoveField):
-                return "remove_%s_%s" % (ops[0].model_name_lower, ops[0].name_lower)
-        elif ops:
-            if all(isinstance(o, operations.CreateModel) for o in ops):
-                return "_".join(sorted(o.name_lower for o in ops))
-        return "auto_%s" % get_migration_name_timestamp()
+            name = ops[0].migration_name_fragment
+        elif len(ops) > 1 and all(isinstance(o, operations.CreateModel) for o in ops):
+            name = '_'.join(sorted(o.migration_name_fragment for o in ops))
+        if name is None:
+            name = 'auto_%s' % get_migration_name_timestamp()
+        return name
 
     @classmethod
     def parse_number(cls, name):

django/db/migrations/operations/base.py

@@ -79,6 +79,14 @@ class Operation:
         """
         return "%s: %s" % (self.__class__.__name__, self._constructor_args)
 
+    @property
+    def migration_name_fragment(self):
+        """
+        A filename part suitable for automatically naming a migration
+        containing this operation, or None if not applicable.
+        """
+        return None
+
     def references_model(self, name, app_label):
         """
         Return True if there is a chance this operation references the given

django/db/migrations/operations/fields.py

@@ -116,6 +116,10 @@ class AddField(FieldOperation):
     def describe(self):
         return "Add field %s to %s" % (self.name, self.model_name)
 
+    @property
+    def migration_name_fragment(self):
+        return '%s_%s' % (self.model_name_lower, self.name_lower)
+
     def reduce(self, operation, app_label):
         if isinstance(operation, FieldOperation) and self.is_same_field_operation(operation):
             if isinstance(operation, AlterField):
@@ -174,6 +178,10 @@ class RemoveField(FieldOperation):
     def describe(self):
         return "Remove field %s from %s" % (self.name, self.model_name)
 
+    @property
+    def migration_name_fragment(self):
+        return 'remove_%s_%s' % (self.model_name_lower, self.name_lower)
+
     def reduce(self, operation, app_label):
         from .models import DeleteModel
         if isinstance(operation, DeleteModel) and operation.name_lower == self.model_name_lower:
@@ -243,6 +251,10 @@ class AlterField(FieldOperation):
     def describe(self):
         return "Alter field %s on %s" % (self.name, self.model_name)
 
+    @property
+    def migration_name_fragment(self):
+        return 'alter_%s_%s' % (self.model_name_lower, self.name_lower)
+
     def reduce(self, operation, app_label):
         if isinstance(operation, RemoveField) and self.is_same_field_operation(operation):
             return [operation]
@@ -354,6 +366,14 @@ class RenameField(FieldOperation):
     def describe(self):
         return "Rename field %s on %s to %s" % (self.old_name, self.model_name, self.new_name)
 
+    @property
+    def migration_name_fragment(self):
+        return 'rename_%s_%s_%s' % (
+            self.old_name_lower,
+            self.model_name_lower,
+            self.new_name_lower,
+        )
+
     def references_field(self, model_name, name, app_label):
         return self.references_model(model_name, app_label) and (
             name.lower() == self.old_name_lower or

django/db/migrations/operations/models.py

@@ -99,6 +99,10 @@ class CreateModel(ModelOperation):
     def describe(self):
         return "Create %smodel %s" % ("proxy " if self.options.get("proxy", False) else "", self.name)
 
+    @property
+    def migration_name_fragment(self):
+        return self.name_lower
+
     def references_model(self, name, app_label):
         name_lower = name.lower()
         if name_lower == self.name_lower:
@@ -273,6 +277,10 @@ class DeleteModel(ModelOperation):
     def describe(self):
         return "Delete model %s" % self.name
 
+    @property
+    def migration_name_fragment(self):
+        return 'delete_%s' % self.name_lower
+
 
 class RenameModel(ModelOperation):
     """Rename a model."""
@@ -397,6 +405,10 @@ class RenameModel(ModelOperation):
     def describe(self):
         return "Rename model %s to %s" % (self.old_name, self.new_name)
 
+    @property
+    def migration_name_fragment(self):
+        return 'rename_%s_%s' % (self.old_name_lower, self.new_name_lower)
+
     def reduce(self, operation, app_label):
         if (isinstance(operation, RenameModel) and
                 self.new_name_lower == operation.old_name_lower):
@@ -470,6 +482,10 @@ class AlterModelTable(ModelOptionOperation):
             self.table if self.table is not None else "(default)"
         )
 
+    @property
+    def migration_name_fragment(self):
+        return 'alter_%s_table' % self.name_lower
+
 
 class AlterTogetherOptionOperation(ModelOptionOperation):
     option_name = None
@@ -526,6 +542,10 @@ class AlterTogetherOptionOperation(ModelOptionOperation):
     def describe(self):
         return "Alter %s for %s (%s constraint(s))" % (self.option_name, self.name, len(self.option_value or ''))
 
+    @property
+    def migration_name_fragment(self):
+        return 'alter_%s_%s' % (self.name_lower, self.option_name)
+
 
 class AlterUniqueTogether(AlterTogetherOptionOperation):
     """
@@ -607,6 +627,10 @@ class AlterOrderWithRespectTo(ModelOptionOperation):
     def describe(self):
         return "Set order_with_respect_to on %s to %s" % (self.name, self.order_with_respect_to)
 
+    @property
+    def migration_name_fragment(self):
+        return 'alter_%s_order_with_respect_to' % self.name_lower
+
 
 class AlterModelOptions(ModelOptionOperation):
     """
@@ -662,6 +686,10 @@ class AlterModelOptions(ModelOptionOperation):
     def describe(self):
         return "Change Meta options on %s" % self.name
 
+    @property
+    def migration_name_fragment(self):
+        return 'alter_%s_options' % self.name_lower
+
 
 class AlterModelManagers(ModelOptionOperation):
     """Alter the model's managers."""
@@ -693,6 +721,10 @@ class AlterModelManagers(ModelOptionOperation):
     def describe(self):
         return "Change managers on %s" % self.name
 
+    @property
+    def migration_name_fragment(self):
+        return 'alter_%s_managers' % self.name_lower
+
 
 class IndexOperation(Operation):
     option_name = 'indexes'
@@ -747,6 +779,10 @@ class AddIndex(IndexOperation):
             self.model_name,
         )
 
+    @property
+    def migration_name_fragment(self):
+        return '%s_%s' % (self.model_name_lower, self.index.name.lower())
+
 
 class RemoveIndex(IndexOperation):
     """Remove an index from a model."""
@@ -789,6 +825,10 @@ class RemoveIndex(IndexOperation):
     def describe(self):
         return 'Remove index %s from %s' % (self.name, self.model_name)
 
+    @property
+    def migration_name_fragment(self):
+        return 'remove_%s_%s' % (self.model_name_lower, self.name.lower())
+
 
 class AddConstraint(IndexOperation):
     option_name = 'constraints'
@@ -821,6 +861,10 @@ class AddConstraint(IndexOperation):
     def describe(self):
         return 'Create constraint %s on model %s' % (self.constraint.name, self.model_name)
 
+    @property
+    def migration_name_fragment(self):
+        return '%s_%s' % (self.model_name_lower, self.constraint.name.lower())
+
 
 class RemoveConstraint(IndexOperation):
     option_name = 'constraints'
@@ -857,3 +901,7 @@ class RemoveConstraint(IndexOperation):
 
     def describe(self):
         return 'Remove constraint %s from model %s' % (self.name, self.model_name)
+
+    @property
+    def migration_name_fragment(self):
+        return 'remove_%s_%s' % (self.model_name_lower, self.name.lower())