kotlin 中的 JPA 错误：“学生”类应该具有 [public，protected] 无参数构造函数

Question

有谁知道我如何解决这个问题：“类‘学生’应该有[公共，受保护]无参数构造函数”？

它在抱怨与SchoolLesson

import javax.persistence.Entity
import javax.persistence.GeneratedValue
import javax.persistence.GenerationType
import javax.persistence.Id
import javax.persistence.JoinColumn
import javax.persistence.ManyToOne


@Entity
data class Student(
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    val id: Long = -1,

    @ManyToOne
    @NotNull
    @JoinColumn(name = "school_lesson_id", referencedColumnName = "id")
    val report: SchoolLesson,

)

#EDIT 根据要求添加了 SchoolLesson

    import javax.persistence.*
    import javax.validation.constraints.NotNull

    @Entity
    data class SchoolLesson(
      @Id
      @GeneratedValue(strategy = GenerationType.IDENTITY)
      @Column(nullable = false)
      val id: Long = -1,
    
      @NotNull
      val name: String = "",
    )

Answer 1

切勿将数据类用于@Entities。会导致以后出现一系列的问题。遵循此处列出的最佳实践：https://www.jpa-buddy.com/blog/best-practices-and-common-pitfalls/。