Refs #35704 -- Used copy.replace() in Operation.reduce() methods.

django/db/migrations/operations/base.py

@@ -1,6 +1,7 @@
 import enum
 
 from django.db import router
+from django.utils.inspect import get_func_args
 
 
 class OperationCategory(str, enum.Enum):
@@ -52,6 +53,16 @@ class Operation:
         self._constructor_args = (args, kwargs)
         return self
 
+    def __replace__(self, /, **changes):
+        args = [
+            changes.pop(name, value)
+            for name, value in zip(
+                get_func_args(self.__class__),
+                self._constructor_args[0],
+            )
+        ]
+        return self.__class__(*args, **(self._constructor_args[1] | changes))
+
     def deconstruct(self):
         """
         Return a 3-tuple of class import path (or just name if it lives

django/db/migrations/operations/fields.py

@@ -1,5 +1,6 @@
 from django.db.migrations.utils import field_references
 from django.db.models import NOT_PROVIDED
+from django.utils.copy import replace
 from django.utils.functional import cached_property
 
 from .base import Operation, OperationCategory
@@ -134,8 +135,8 @@ class AddField(FieldOperation):
         ):
             if isinstance(operation, AlterField):
                 return [
-                    AddField(
-                        model_name=self.model_name,
+                    replace(
+                        self,
                         name=operation.name,
                         field=operation.field,
                     ),
@@ -143,13 +144,7 @@ class AddField(FieldOperation):
             elif isinstance(operation, RemoveField):
                 return []
             elif isinstance(operation, RenameField):
-                return [
-                    AddField(
-                        model_name=self.model_name,
-                        name=operation.new_name,
-                        field=self.field,
-                    ),
-                ]
+                return [replace(self, name=operation.new_name)]
         return super().reduce(operation, app_label)
 
 
@@ -264,11 +259,7 @@ class AlterField(FieldOperation):
         ):
             return [
                 operation,
-                AlterField(
-                    model_name=self.model_name,
-                    name=operation.new_name,
-                    field=self.field,
-                ),
+                replace(self, name=operation.new_name),
             ]
         return super().reduce(operation, app_label)
 
@@ -350,13 +341,7 @@ class RenameField(FieldOperation):
             and self.is_same_model_operation(operation)
             and self.new_name_lower == operation.old_name_lower
         ):
-            return [
-                RenameField(
-                    self.model_name,
-                    self.old_name,
-                    operation.new_name,
-                ),
-            ]
+            return [replace(self, new_name=operation.new_name)]
         # Skip `FieldOperation.reduce` as we want to run `references_field`
         # against self.old_name and self.new_name.
         return super(FieldOperation, self).reduce(operation, app_label) or not (

django/db/migrations/operations/models.py

@@ -1,8 +1,11 @@
+from copy import copy
+
 from django.db import models
 from django.db.migrations.operations.base import Operation, OperationCategory
 from django.db.migrations.state import ModelState
 from django.db.migrations.utils import field_references, resolve_relation
 from django.db.models.options import normalize_together
+from django.utils.copy import replace
 from django.utils.functional import cached_property
 
 from .fields import AddField, AlterField, FieldOperation, RemoveField, RenameField
@@ -156,15 +159,7 @@ class CreateModel(ModelOperation):
             isinstance(operation, RenameModel)
             and self.name_lower == operation.old_name_lower
         ):
-            return [
-                CreateModel(
-                    operation.new_name,
-                    fields=self.fields,
-                    options=self.options,
-                    bases=self.bases,
-                    managers=self.managers,
-                ),
-            ]
+            return [replace(self, name=operation.new_name)]
         elif (
             isinstance(operation, AlterModelOptions)
             and self.name_lower == operation.name_lower
@@ -173,42 +168,20 @@ class CreateModel(ModelOperation):
             for key in operation.ALTER_OPTION_KEYS:
                 if key not in operation.options:
                     options.pop(key, None)
-            return [
-                CreateModel(
-                    self.name,
-                    fields=self.fields,
-                    options=options,
-                    bases=self.bases,
-                    managers=self.managers,
-                ),
-            ]
+            return [replace(self, options=options)]
         elif (
             isinstance(operation, AlterModelManagers)
             and self.name_lower == operation.name_lower
         ):
-            return [
-                CreateModel(
-                    self.name,
-                    fields=self.fields,
-                    options=self.options,
-                    bases=self.bases,
-                    managers=operation.managers,
-                ),
-            ]
+            return [replace(self, managers=operation.managers)]
         elif (
             isinstance(operation, AlterModelTable)
             and self.name_lower == operation.name_lower
         ):
             return [
-                CreateModel(
-                    self.name,
-                    fields=self.fields,
-                    options={
-                        **self.options,
-                        "db_table": operation.table,
-                    },
-                    bases=self.bases,
-                    managers=self.managers,
+                replace(
+                    self,
+                    options={**self.options, "db_table": operation.table},
                 ),
             ]
         elif (
@@ -216,15 +189,12 @@ class CreateModel(ModelOperation):
             and self.name_lower == operation.name_lower
         ):
             return [
-                CreateModel(
-                    self.name,
-                    fields=self.fields,
+                replace(
+                    self,
                     options={
                         **self.options,
                         "db_table_comment": operation.table_comment,
                     },
-                    bases=self.bases,
-                    managers=self.managers,
                 ),
             ]
         elif (
@@ -232,15 +202,12 @@ class CreateModel(ModelOperation):
             and self.name_lower == operation.name_lower
         ):
             return [
-                CreateModel(
-                    self.name,
-                    fields=self.fields,
+                replace(
+                    self,
                     options={
                         **self.options,
                         **{operation.option_name: operation.option_value},
                     },
-                    bases=self.bases,
-                    managers=self.managers,
                 ),
             ]
         elif (
@@ -248,15 +215,12 @@ class CreateModel(ModelOperation):
             and self.name_lower == operation.name_lower
         ):
             return [
-                CreateModel(
-                    self.name,
-                    fields=self.fields,
+                replace(
+                    self,
                     options={
                         **self.options,
                         "order_with_respect_to": operation.order_with_respect_to,
                     },
-                    bases=self.bases,
-                    managers=self.managers,
                 ),
             ]
         elif (
@@ -265,25 +229,19 @@ class CreateModel(ModelOperation):
         ):
             if isinstance(operation, AddField):
                 return [
-                    CreateModel(
-                        self.name,
+                    replace(
+                        self,
                         fields=self.fields + [(operation.name, operation.field)],
-                        options=self.options,
-                        bases=self.bases,
-                        managers=self.managers,
                     ),
                 ]
             elif isinstance(operation, AlterField):
                 return [
-                    CreateModel(
-                        self.name,
+                    replace(
+                        self,
                         fields=[
                             (n, operation.field if n == operation.name else v)
                             for n, v in self.fields
                         ],
-                        options=self.options,
-                        bases=self.bases,
-                        managers=self.managers,
                     ),
                 ]
             elif isinstance(operation, RemoveField):
@@ -308,16 +266,14 @@ class CreateModel(ModelOperation):
                 if order_with_respect_to == operation.name_lower:
                     del options["order_with_respect_to"]
                 return [
-                    CreateModel(
-                        self.name,
+                    replace(
+                        self,
                         fields=[
                             (n, v)
                             for n, v in self.fields
                             if n.lower() != operation.name_lower
                         ],
                         options=options,
-                        bases=self.bases,
-                        managers=self.managers,
                     ),
                 ]
             elif isinstance(operation, RenameField):
@@ -336,15 +292,13 @@ class CreateModel(ModelOperation):
                 if order_with_respect_to == operation.old_name:
                     options["order_with_respect_to"] = operation.new_name
                 return [
-                    CreateModel(
-                        self.name,
+                    replace(
+                        self,
                         fields=[
                             (operation.new_name if n == operation.old_name else n, v)
                             for n, v in self.fields
                         ],
                         options=options,
-                        bases=self.bases,
-                        managers=self.managers,
                     ),
                 ]
         elif (
@@ -353,9 +307,8 @@ class CreateModel(ModelOperation):
         ):
             if isinstance(operation, AddIndex):
                 return [
-                    CreateModel(
-                        self.name,
-                        fields=self.fields,
+                    replace(
+                        self,
                         options={
                             **self.options,
                             "indexes": [
@@ -363,8 +316,6 @@ class CreateModel(ModelOperation):
                                 operation.index,
                             ],
                         },
-                        bases=self.bases,
-                        managers=self.managers,
                     ),
                 ]
             elif isinstance(operation, RemoveIndex):
@@ -374,22 +325,18 @@ class CreateModel(ModelOperation):
                     if index.name != operation.name
                 ]
                 return [
-                    CreateModel(
-                        self.name,
-                        fields=self.fields,
+                    replace(
+                        self,
                         options={
                             **self.options,
                             "indexes": options_indexes,
                         },
-                        bases=self.bases,
-                        managers=self.managers,
                     ),
                 ]
             elif isinstance(operation, AddConstraint):
                 return [
-                    CreateModel(
-                        self.name,
-                        fields=self.fields,
+                    replace(
+                        self,
                         options={
                             **self.options,
                             "constraints": [
@@ -397,8 +344,6 @@ class CreateModel(ModelOperation):
                                 operation.constraint,
                             ],
                         },
-                        bases=self.bases,
-                        managers=self.managers,
                     ),
                 ]
             elif isinstance(operation, RemoveConstraint):
@@ -408,15 +353,12 @@ class CreateModel(ModelOperation):
                     if constraint.name != operation.name
                 ]
                 return [
-                    CreateModel(
-                        self.name,
-                        fields=self.fields,
+                    replace(
+                        self,
                         options={
                             **self.options,
                             "constraints": options_constraints,
                         },
-                        bases=self.bases,
-                        managers=self.managers,
                     ),
                 ]
         return super().reduce(operation, app_label)
@@ -567,12 +509,7 @@ class RenameModel(ModelOperation):
             isinstance(operation, RenameModel)
             and self.new_name_lower == operation.old_name_lower
         ):
-            return [
-                RenameModel(
-                    self.old_name,
-                    operation.new_name,
-                ),
-            ]
+            return [replace(self, new_name=operation.new_name)]
         # Skip `ModelOperation.reduce` as we want to run `references_model`
         # against self.new_name.
         return super(ModelOperation, self).reduce(
@@ -990,8 +927,9 @@ class AddIndex(IndexOperation):
         if isinstance(operation, RemoveIndex) and self.index.name == operation.name:
             return []
         if isinstance(operation, RenameIndex) and self.index.name == operation.old_name:
-            self.index.name = operation.new_name
-            return [self.__class__(model_name=self.model_name, index=self.index)]
+            index = copy(self.index)
+            index.name = operation.new_name
+            return [replace(self, index=index)]
         return super().reduce(operation, app_label)
 
 
@@ -1183,14 +1121,7 @@ class RenameIndex(IndexOperation):
             and operation.old_name
             and self.new_name_lower == operation.old_name_lower
         ):
-            return [
-                RenameIndex(
-                    self.model_name,
-                    new_name=operation.new_name,
-                    old_name=self.old_name,
-                    old_fields=self.old_fields,
-                )
-            ]
+            return [replace(self, new_name=operation.new_name)]
         return super().reduce(operation, app_label)
 
 
@@ -1247,7 +1178,7 @@ class AddConstraint(IndexOperation):
             and self.model_name_lower == operation.model_name_lower
             and self.constraint.name == operation.name
         ):
-            return [AddConstraint(self.model_name, operation.constraint)]
+            return [replace(self, constraint=operation.constraint)]
         return super().reduce(operation, app_label)
 
 

django/utils/copy.py

@@ -0,0 +1,17 @@
+from django.utils.version import PY313
+
+if PY313:
+    from copy import replace
+else:
+    # Backport of copy.replace() from Python 3.13.
+    def replace(obj, /, **changes):
+        """Return a new object replacing specified fields with new values.
+
+        This is especially useful for immutable objects, like named tuples or
+        frozen dataclasses.
+        """
+        cls = obj.__class__
+        func = getattr(cls, "__replace__", None)
+        if func is None:
+            raise TypeError(f"replace() does not support {cls.__name__} objects")
+        return func(obj, **changes)