[BUG] Sort m2m fields before comparing them with diff(...) (#271)

* 🐛 Sort m2m fields before comparing them with `diff(...)`

* Add test case and upgrade changelog

---------

Co-authored-by: Waket Zheng <waketzheng@gmail.com>

CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## 0.8
 
+### [0.8.1](Unreleased)
+
+#### Fixed
+- Sort m2m fields before comparing them with diff. (#271)
+
 ### [0.8.0](../../releases/tag/v0.8.0) - 2024-12-04
 
 - Fix the issue of parameter concatenation when generating ORM with inspectdb (#331)

aerich/migrate.py

@@ -271,6 +271,10 @@ class Migrate:
                 # m2m fields
                 old_m2m_fields = cast(List[dict], old_model_describe.get("m2m_fields"))
                 new_m2m_fields = cast(List[dict], new_model_describe.get("m2m_fields"))
+                if old_m2m_fields and len(new_m2m_fields) >= 2:
+                    length = len(old_m2m_fields)
+                    field_index = {f["name"]: i for i, f in enumerate(new_m2m_fields)}
+                    new_m2m_fields.sort(key=lambda field: field_index.get(field["name"], length))
                 for action, _, change in diff(old_m2m_fields, new_m2m_fields):
                     if change[0][0] == "db_constraint":
                         continue

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "aerich"
-version = "0.8.0"
+version = "0.8.1"
 description = "A database migrations tool for Tortoise ORM."
 authors = ["long2ice <long2ice@gmail.com>"]
 license = "Apache-2.0"

tests/models.py

@@ -31,6 +31,8 @@ class User(Model):
     intro = fields.TextField(default="")
     longitude = fields.DecimalField(max_digits=10, decimal_places=8)
 
+    products: fields.ManyToManyRelation["Product"]
+
 
 class Email(Model):
     email_id = fields.IntField(primary_key=True)
@@ -56,6 +58,9 @@ class Category(Model):
 
 class Product(Model):
     categories: fields.ManyToManyRelation[Category] = fields.ManyToManyField("models.Category")
+    users: fields.ManyToManyRelation[User] = fields.ManyToManyField(
+        "models.User", related_name="products"
+    )
     name = fields.CharField(max_length=50)
     view_num = fields.IntField(description="View Num", default=0)
     sort = fields.IntField()

tests/test_migrate.py

@@ -846,6 +846,7 @@ def test_migrate(mocker: MockerFixture):
     - add unique: User.username
     - change column: length User.password
     - add unique_together: (name,type) of Product
+    - add one more many to many field: Product.users
     - drop unique field: Config.name
     - alter default: Config.status
     - rename column: Product.image -> Product.pic
@@ -902,6 +903,7 @@ def test_migrate(mocker: MockerFixture):
             "ALTER TABLE `category` MODIFY COLUMN `created_at` DATETIME(6) NOT NULL  DEFAULT CURRENT_TIMESTAMP(6)",
             "ALTER TABLE `product` MODIFY COLUMN `body` LONGTEXT NOT NULL",
             "ALTER TABLE `email` MODIFY COLUMN `is_primary` BOOL NOT NULL  DEFAULT 0",
+            "CREATE TABLE `product_user` (\n    `product_id` INT NOT NULL REFERENCES `product` (`id`) ON DELETE CASCADE,\n    `user_id` INT NOT NULL REFERENCES `user` (`id`) ON DELETE CASCADE\n) CHARACTER SET utf8mb4",
         }
         expected_downgrade_operators = {
             "ALTER TABLE `category` MODIFY COLUMN `name` VARCHAR(200) NOT NULL",
@@ -928,6 +930,7 @@ def test_migrate(mocker: MockerFixture):
             "ALTER TABLE `user` MODIFY COLUMN `password` VARCHAR(200) NOT NULL",
             "DROP TABLE IF EXISTS `email_user`",
             "DROP TABLE IF EXISTS `newmodel`",
+            "DROP TABLE IF EXISTS `product_user`",
             "ALTER TABLE `user` MODIFY COLUMN `intro` LONGTEXT NOT NULL",
             "ALTER TABLE `config` MODIFY COLUMN `value` TEXT NOT NULL",
             "ALTER TABLE `category` MODIFY COLUMN `created_at` DATETIME(6) NOT NULL  DEFAULT CURRENT_TIMESTAMP(6)",
@@ -987,6 +990,7 @@ def test_migrate(mocker: MockerFixture):
             'CREATE TABLE IF NOT EXISTS "newmodel" (\n    "id" SERIAL NOT NULL PRIMARY KEY,\n    "name" VARCHAR(50) NOT NULL\n);\nCOMMENT ON COLUMN "config"."user_id" IS \'User\'',
             'CREATE UNIQUE INDEX "uid_product_name_869427" ON "product" ("name", "type_db_alias")',
             'CREATE UNIQUE INDEX "uid_user_usernam_9987ab" ON "user" ("username")',
+            'CREATE TABLE "product_user" (\n    "product_id" INT NOT NULL REFERENCES "product" ("id") ON DELETE CASCADE,\n    "user_id" INT NOT NULL REFERENCES "user" ("id") ON DELETE CASCADE\n)',
         }
         expected_downgrade_operators = {
             'CREATE UNIQUE INDEX "uid_category_title_f7fc03" ON "category" ("title")',
@@ -1018,6 +1022,7 @@ def test_migrate(mocker: MockerFixture):
             'ALTER TABLE "product" ALTER COLUMN "created_at" TYPE TIMESTAMPTZ USING "created_at"::TIMESTAMPTZ',
             'ALTER TABLE "product" ALTER COLUMN "is_reviewed" TYPE BOOL USING "is_reviewed"::BOOL',
             'ALTER TABLE "product" ALTER COLUMN "body" TYPE TEXT USING "body"::TEXT',
+            'DROP TABLE IF EXISTS "product_user"',
             'DROP INDEX "idx_product_name_869427"',
             'DROP INDEX "idx_email_email_4a1a33"',
             'DROP INDEX "uid_user_usernam_9987ab"',