May 2025
Intermediate to advanced
208 pages
2h 55m
Japanese
Content preview from Essential SQLAlchemy， 2nd Edition
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第12章. マイグレーションを構築する
この作品はAIを使って翻訳されている。ご意見、ご感想をお待ちしている：translation-feedback@oreilly.com
第11章では、Alembicマイグレーション環境を初期化して設定し、アプリケーションにデータクラスを追加する準備と、それらをデータベースに追加するためのマイグレーションを作成した。テーブルを追加するためにautogenerateを使う方法と、autogenerateではできないことを実現するためにマイグレーションを手作りする方法について検討する。空のマイグレーションから始めるのは常に良いアイデアである。
ベースとなる空のマイグレーションを生成する
ベースとなる空のマイグレーションを作成するには、本書のサンプルコードのCH12/フォルダにいることを確認する。このコマンドを使って空のマイグレーションを作成する：
# alembic revision -m "Empty Init"Generatingch12/alembic/versions/8a8a9d067_empty_init.py...done
alembic revisionコマンドを実行し、マイグレーションにメッセージ (-m)"Empty Init"を追加する。
これでalembic/versions/サブフォルダーにマイグレーションファイルが作成される。ファイル名は常にリビジョンIDを表すハッシュで始まり、次にあなたが指定したメッセージが続く。 このファイルの中を見てみよう：
"""Empty InitRevision ID: 8a8a9d067 Revises: Create Date: 2015-09-13 20:10:05.486995 """# revision identifiers, used by Alembic.revision='8a8a9d067'down_revision=Nonebranch_labels=Nonedepends_on=Nonefrom ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.