英文:
How to deal with metadata in a Many-To-Many relationship with Spring Data JDBC?
问题
我有一个项目，在这个项目中，bot_user 在 game_table 中进行游戏。因此，我有一个连接表。我还在该连接表中存储了 buy_in（玩家在桌子上可用的点数）。我的 SQL 代码如下：
CREATE TABLE bot_users (
user_id bigint PRIMARY KEY,
free_points bigint CHECK (free_points >= 0),
frozen_points bigint CHECK (frozen_points >= 0)
);
CREATE TABLE game_tables (
channel_id bigint PRIMARY KEY,
owner bigint REFERENCES bot_users(user_id),
in_game boolean NOT NULL
);
CREATE TABLE game_tables_participants (
game_table_id bigint REFERENCES game_tables(channel_id),
participant_id bigint REFERENCES bot_users(user_id),
buy_in bigint NOT NULL,
PRIMARY KEY (game_table_id, participant_id)
);
我的问题是：如何在 Java 实体中表示buy_in元数据？如果没有buy_in，我将简单地在GameTable实体中有一个ParticipantRef，然后有一些使用 ID 的方法。但我希望在代码中也能使用 buy_in，所以我应该创建一个类似于ParticipantRef的实体，其中包含buy_in吗？如果是的话，那么如何进行持久化？
(Note: The code you provided contains HTML-encoded characters for greater than and less than signs, which I've left as is in the translation.)
英文:
I have a project, where bot_users play in game_tables. So I have a join table. I also store the buy_in (points available to the player at the table) in that join table. My SQL:
CREATE TABLE bot_users (
user_id bigint PRIMARY KEY,
free_points bigint CHECK (free_points >= 0),
frozen_points bigint CHECK (frozen_points >= 0)
);
CREATE TABLE game_tables (
channel_id bigint PRIMARY KEY,
owner bigint REFERENCES bot_users(user_id),
in_game boolean NOT NULL
);
CREATE TABLE game_tables_participants (
game_table_id bigint REFERENCES game_tables(channel_id),
participant_id bigint REFERENCES bot_users(user_id),
buy_in bigint NOT NULL,
PRIMARY KEY (game_table_id, participant_id)
);
My question now is: how do I represent that buy_in metadata in entities in Java? If buy_in didn't exist, I would simply have a ParticipantRef of which I would have a Set in the GameTable entity, and then have methods that work on IDs there. But I want to have buy_in available in the code too, so should I create a ParticipantRef-like entity that contains the buy_in? If yes, then how would persisting it work?
答案1
得分: 0
你提出的解决方案基本上是完成此操作的方式。与其仅使用BotUsers的userId来拥有ParticipantRef，它还会获得一个buyIn属性。
由于您从GameTable通过Set对ParticipantRef进行了对象引用，它将被视为GameTable聚合的一部分，并且在持久化GameTable实例时也会被持久化。
英文:
Your proposed solution is pretty much the way to do this. Instead of having a ParticipantRef with just the userId of the BotUsers it also gets a buyIn attribute.
Since you have an object references from GameTable via a Set to the ParticipantRef it will be considered part of the GameTable-Aggregate and get persisted whenever you persist a GameTable instance.
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