如何在Room @Query中使用参数字段? [英] How to use parameter fields in Room @Query?

问题描述

我有一个User类，其字段为id，所以我想使用Room运行以下查询:

I have a User class with a field id, so I wanted to run the following query with Room:

@Query("SELECT * FROM ticket where user_id = :user.id")
LiveData<Ticket> loadFromUser(User user);

但是我在user.id的Android Studio上收到错误标记，并且我在网上找到的所有示例都仅使用@Query方法的直接参数，通常是String或int.

But I am getting error marks on Android Studio on user.id and all examples I find online only use the direct parameter of the @Query method, usually a String or an int.

是否可以在房间@Query中使用对象的字段?如果为正，那么引用它的正确方法是什么.

Is it possible to use an object's field in a Room @Query? If positive, so what's the proper way of referencing it.

推荐答案

您不能将类似的参数传递给房间.它不支持完整的表达语言.您必须使用基本类型来传递参数.像这样

You can't pass parameters like that to room. It does not support a full expression language. You have to use primitive types to pass parameters. Like this,

@Query("SELECT * FROM ticket where user_id = :user_id")
LiveData<Ticket> loadFromUser(String user_id);

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