Merge pull request #327 from ar0ne/dev

Added an option to generate empty migration file

README.md

@@ -113,6 +113,14 @@ If `aerich` guesses you are renaming a column, it will ask `Rename {old_column}
 `True` to rename column without column drop, or choose `False` to drop the column then create. Note that the latter may
 lose data.
 
+If you need to manually write migration, you could generate empty file:
+
+```shell
+> aerich migrate --name add_index --empty
+
+Success migrate 1_202326122220101229_add_index.py
+```
+
 ### Upgrade to latest version
 
 ```shell

aerich/__init__.py

@@ -123,8 +123,8 @@ class Command:
         inspect = cls(connection, tables)
         return await inspect.inspect()
 
-    async def migrate(self, name: str = "update"):
+    async def migrate(self, name: str = "update", empty: bool = False) -> str:
-        return await Migrate.migrate(name)
+        return await Migrate.migrate(name, empty)
 
     async def init_db(self, safe: bool):
         location = self.location

aerich/cli.py

@@ -79,6 +79,7 @@ async def cli(ctx: Context, config, app):
 
 @cli.command(help="Generate migrate changes file.")
 @click.option("--name", default="update", show_default=True, help="Migrate name.")
+@click.option("--empty", default=False, is_flag=True, help="Generate empty migration file.")
 @click.pass_context
 @coro
 async def migrate(ctx: Context, name):

aerich/migrate.py

@@ -120,22 +120,23 @@ class Migrate:
                 os.unlink(Path(cls.migrate_location, version_file))
 
         version_file = Path(cls.migrate_location, version)
-        content = MIGRATE_TEMPLATE.format(
+        content = cls._get_diff_file_content()
-            upgrade_sql=";\n        ".join(cls.upgrade_operators) + ";",
-            downgrade_sql=";\n        ".join(cls.downgrade_operators) + ";",
-        )
 
         with open(version_file, "w", encoding="utf-8") as f:
             f.write(content)
         return version
 
     @classmethod
-    async def migrate(cls, name) -> str:
+    async def migrate(cls, name: str, empty: bool) -> str:
         """
         diff old models and new models to generate diff content
-        :param name:
+        :param name: str name for migration
+        :param empty: bool if True generates empty migration
         :return:
         """
+        if empty:
+            return await cls._generate_diff_py(name)
+
         new_version_content = get_models_describe(cls.app)
         cls.diff_models(cls._last_version_content, new_version_content)
         cls.diff_models(new_version_content, cls._last_version_content, False)
@@ -147,6 +148,21 @@ class Migrate:
 
         return await cls._generate_diff_py(name)
 
+    @classmethod
+    def _get_diff_file_content(cls) -> str:
+        """
+        builds content for diff file from template
+        """
+        def join_lines(lines: List[str]) -> str:
+            if not lines:
+                return ""
+            return ";\n        ".join(lines) + ";"
+            
+        return MIGRATE_TEMPLATE.format(
+            upgrade_sql=join_lines(cls.upgrade_operators), 
+            downgrade_sql=join_lines(cls.downgrade_operators)
+        )
+
     @classmethod
     def _add_operator(cls, operator: str, upgrade=True, fk_m2m_index=False):
         """

tests/test_migrate.py

@@ -1,3 +1,6 @@
+import tempfile
+from pathlib import Path
+
 import pytest
 from pytest_mock import MockerFixture
 
@@ -5,7 +8,7 @@ from aerich.ddl.mysql import MysqlDDL
 from aerich.ddl.postgres import PostgresDDL
 from aerich.ddl.sqlite import SqliteDDL
 from aerich.exceptions import NotSupportError
-from aerich.migrate import Migrate
+from aerich.migrate import MIGRATE_TEMPLATE, Migrate
 from aerich.utils import get_models_describe
 
 old_models_describe = {
@@ -966,3 +969,15 @@ def test_sort_all_version_files(mocker):
         "10_datetime_update.py",
         "11_datetime_update.py",
     ]
+
+async def test_empty_migration(mocker) -> None:
+    mocker.patch("os.listdir", return_value=[])
+    Migrate.app = "foo"
+    expected_content = MIGRATE_TEMPLATE.format(upgrade_sql="", downgrade_sql="")
+    with tempfile.TemporaryDirectory() as temp_dir:
+        Migrate.migrate_location = temp_dir
+
+        migration_file = await Migrate.migrate("update", True)
+
+        with open(Path(temp_dir, migration_file), "r") as f:
+            assert f.read() == expected_content