Question

我在连接工作时遇到问题，两个表定义如下：

public class Student { 
    @ForeignCollectionField(eager = true, columnName = STUDENT_INSTANCE_COLLECTION_NAME)
    private ForeignCollection<StudentInstance> studentInstances;

    ...
}

public class StudentInstance {
    public static final String STUDENT_ID_COLUMN = "student_id";
    public static final String REGISTER_ID_COLUMN = "register_id";

    @DatabaseField(generatedId = true)
    private int id;

    @DatabaseField(canBeNull = false, foreign = true)
    private Student student;

    @DatabaseField(canBeNull = false, foreign = true)
    private Register register;

   ...

}

活动代码：

public List<Student> getStudents( int registerId ) {
    QueryBuilder<StudentInstance, Integer> studentInstanceQb =  studentInstanceDao.getDAO().queryBuilder();
    studentInstanceQb.where().eq(StudentInstance.REGISTER_ID_COLUMN, registerId);
    QueryBuilder<Student, Integer> studentQb =  getDAO().queryBuilder();    
    studentQb.join(studentInstanceQb).query();
}

当我运行代码时，我得到了异常：

getStudents出错：java.sql.SQLException：找不到外来的 class com.beardedhen.roster.db.entity.Student in class in class com.beardedhen.roster.db.entity.StudentInstance，反之亦然

这可能是一个愚蠢的错误，但我用它打了一堵完整的砖墙。

感谢您的帮助，

安迪

Answer 1

看一下QueryBuilder。 matchJoinedFields（），异常来自。您将看到当前（4.42）实现如何检查表并查找连接的连接列。

Ormlite Join没有外键异常

1 个答案: