Annotation参数必须是一个编译时间常数 [英] An Annotation argument must be a compile time constant

问题描述

我看到了这个问题.类似的错误.但就我而言，情况有所不同.

i have seen this question. Similar error.But in my case it is different.

与Room I一起工作时，正在创建桌子.工作正常.

While working with Room i was creating table. it was working fine.

@Daointerface 
UserDao {
@Query("SELECT * FROM user")
fun getAll(): List<User>

@Insert(onConflict = OnConflictStrategy.REPLACE)
fun insert(user: User)

@Delete
fun delete(user: User)}

但是后来我发现所有表名都必须存储在不同的类中.像表名用户"一样->存储在不同的类中.

but then i found all table Names must be stored in a different class. like table name "user" - > Stored in different class.

例如.

class Table {
companion object {
    const val USER_TABLE = "user"
}}

但是下面的代码不起作用. 它没有从Table类中获取表名.出现编译时错误. "Annotation参数必须是一个编译时间常数"，请帮帮我.里面有什么问题

But below code is not working . it is not picking up table name from Table class. Giving compile time error . "An Annotation argument must be a compile time constant" please help me out.What wrong in it

@Query("SELECT * FROM $Table.USER_TABLE")
fun getAll(): List<User>

推荐答案

问题是错误中指出的问题，您无法为@Query批注动态定义参数.如果要在其他地方定义表的名称，请使用字符串连接.您可以这样做:

The problem is the one stated in the error, you can't have dynamically defined arguments for your @Query annotation. If you want to define the name of the table somewhere else, use string concatenation. You can do it like this:

@Query("SELECT * FROM " + Table.USER_TABLE)
fun getAll(): List<User>

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