错误：查询返回的列没有

Question

我正在实现房间数据库。这是我的POJO类

public class Task implements Serializable {

    @PrimaryKey(autoGenerate = true)
    private int id;

    @ColumnInfo(name = "task_name")
    private String task;

    @ColumnInfo(name = "description")
    private String desc;

    @ColumnInfo(name = "finish_by")
    private String finishBy;

    @ColumnInfo(name = "finished")
    private boolean finished;

    @ColumnInfo(name="no_of_days")
    private String no_of_days;

    public String getNo_of_days() {
        return no_of_days;
    }

    public void setNo_of_days(String no_of_days) {
        this.no_of_days = no_of_days;
    }

}

这是DAO类

@Dao
public interface TaskDao {

    @Update
    void update(Task task);
    @Query("SELECT task_name,description,no_of_days FROM task")
    List<Task> getTasksandDescription();
}

在运行我的代码时，我收到以下错误

com.example.myapplication1.model.Task has some fields [id, finish_by, finished] which are not returned by the query. If they are not supposed to be read from the result, you can mark them with @Ignore annotation. You can suppress this warning by annotating the method with @SuppressWarnings(RoomWarnings.CURSOR_MISMATCH). 
Columns returned by the query: task_name, description, no_of_days. Fields in com.example.myapplication1.model.Task: id, task_name, description, finish_by, finished, no_of_days.

Answer 1

这不是一个错误，而是一个警告，它告诉您正在将SQL映射到Pojo，但没有返回设置Pojo所需的所有字段。因此类的字段比查询返回的字段多,您可以通过执行以下操作来解决这一问题。

I.执行select*以返回所有字段

@Query("SELECT * FROM task")

ii.在不感兴趣的字段中添加@Ignore注释

iii.创建另一个Java类，它只包含您感兴趣的字段，并从查询返回。