java - Hibernate @OneToMany 关联尝试设置 null FK 值

Question

我有以下简单的例子。当它运行时，我看到使用自动生成的 id 生成了 QuoteRequest 对象。接下来，我看到正在生成 Accidents 对象，但插入的 quote_request_id 为 null，因此出现错误:

“quote_request_id”列不能为空

@Entity
@Table(name = "Quotes")
public class QuoteRequest
{
    public QuoteRequest(){}

    @Id
    @Column(name = "quote_request_id")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long QuoteRequestId;


    @OneToMany(mappedBy = "quoteRequest", cascade = CascadeType.ALL)
    @OrderColumn(name = "accidents_id")
    private Accidents[] accidents;

    // Getters and setters
}

@Entity
@Table(name = "Accidents")
public class Accidents
{
    public Accidents()
    {
    }

    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "accidents_id")
    private long AccidentId;


    @Column(name = "amount", nullable = false)
    private Float amount;

    @ManyToOne(optional = false, cascade = CascadeType.ALL)
    @JoinColumn(name = "quote_request_id", nullable = false)
    private QuoteRequest quoteRequest;

    // Getters and setters
}

为什么不将新生成的 ID 插入事故列中？

Answer 1

首先，将 @OneToMany 从使用数组更改为使用 List:

@OneToMany(mappedBy = "quoteRequest", cascade = CascadeType.ALL)
@OrderColumn(name = "accidents_id")
private List<Accidents> accidents = new ArrayList()<>;

确保您设置了关联的双方:

QuoteRequest quoteRequest = ...
Accidents accidents = ...

quoteRequest.getAccidents().add(accident);
accident.setQuoteRequest(quoteRequest);