续集多对多连接的位置

2022-01-19 00:00:00 postgresql orm express javascript sequelize.js

我希望有人可以帮助我.我正在为 express.js 使用 Sequelize ORM，并且我在 2 个表之间有一个有效的多对多关系.

I am hoping somebody can help me. I am using the Sequelize ORM for express.js and I have a working many-to-many relationship between 2 tables.

为了简化我的查询，假设我的表是用户、书籍和用户书籍，其中用户书籍有用户 ID、书籍 ID 和一个附加列(假设它的 NoOfTimesRead).

For the sake of simplifying my query lets pretend my tables are Users, Books and UserBooks where UserBooks has UserId, BookId and an additional column (Lets say its NoOfTimesRead).

我想做的是这样的:

user.getBooks({
  where: {
    "userBooks.NoOfTimesRead": 0
  }
});

如果我输入:

user.getBooks();

这有效并返回所有书籍，我只是无法弄清楚如何通过连接表上的附加列来查询它.

This works and returns all books, I just haven't been able to figure out how to query this by the additional column on the joining table.

我希望这是有道理的，

感谢观看！

推荐答案

使用 Belongs-To-Many，您可以基于直通关系和选择特定属性.例如将 findAll 与 through 一起使用

With Belongs-To-Many you can query based on through relation and select specific attributes. For example using findAll with through

User.findAll({
  include: [{
    model: Project,
      through: {
        attributes: ['createdAt', 'startedAt', 'finishedAt']
          where: {completed: true}
      }
   }] 
 });

基本上你可以使用 through 选项和 include 你链接的关系.更多信息请参见这里

Basically you can use through option and include the relationship that you linked. More can be found here

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