spring boot字段始终为空，即使在post-ing之后也是如此

Question

我有一个logincredential类：

public class LoginCredential {
    @Id @GeneratedValue Long userID;
    String eMail;
    String passwordHash;
    @OneToOne(mappedBy = "loginCredential", fetch = FetchType.LAZY)
    User user;
    LoginCredential(){}
    public LoginCredential(String eMail, String passwordHash, User user) 
    {
        this.eMail = eMail;
        this.passwordHash = passwordHash;
        this.user = user;
    }
}

那么我有user类：

public class User {
    @Id @GeneratedValue Long userID;
    @OneToOne(fetch = FetchType.LAZY,targetEntity = LoginCredential.class)
    @JoinColumn(name = "userID",referencedColumnName = "userID")
    @JsonIgnore
    private LoginCredential loginCredential;
    public User(){}
    public User(String eMail)
    {
          this.eMail=eMail;
    }
    public User(String eMail, LoginCredential loginCredential) {
        this.eMail = eMail;
        this.loginCredential = loginCredential;
    }
}

在我的系统中，首先创建logincredential的一个实例。

但对我来说，问题是在创建该实例之后，user字段仍然为null。

由于它们是一一对应的，有没有其他的方法做它？

我已经尝试了以下操作:{“email”：“[e-mail]”，“passwordhash”：“A665A45920422F9D417E4867EFDC4FB8A04A1F3FFF1FA07E998E86F7F7A27AE3”，“user”：{“userid”：801,“email”：“[e-mail]”}}

我在前端使用的方法，在我的react.js应用程序中：

createUserAndCredential = () => {

  var xhr = new XMLHttpRequest();
  xhr.open('POST', 'http://localhost:8080/login/');
  xhr.setRequestHeader("Content-Type", "application/json");
  xhr.send(JSON.stringify({
    email: this.state.email,
    passwordHash: this.state.passwordHash
  }));
  let that = this;
  xhr.onreadystatechange = function() {
    if (this.readyState === 4 && this.status === 200) {
      console.log(this.responseText);
      /*
      console.log(this.responseText);
      console.log(that.state.newLoginCredential);
      */

      that.state.newLoginCredential = this.responseText.toString();


      var xhr1 = new XMLHttpRequest();
      xhr1.open('POST', 'http://localhost:8080/user/');
      xhr1.setRequestHeader("Content-Type", "application/json");
      console.log(that.state.newLoginCredential);

      let user = JSON.stringify({
        email: that.state.email,
        loginCredential: JSON.parse(that.state.newLoginCredential)
      });

      //console.log(loginCredential);

      xhr1.send(user);

    } else if (this.readyState !== 4 && this.status !== 200) {
      console.log(this.status);
    }
  };
};

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>

这给了我一个警告：

已解决[org.springframework.http.converter.httpmessagenotreadableException：JSON分析错误：无法构造com.mua.cse616.model.logincredential的实例（尽管至少存在一个创建者）：没有可从字符串值反序列化的字符串参数构造函数/工厂方法（“{”email“：”[e-mail]“,”passwordhash“：”A665A45920422F9D417E4867EFDC4FB8A04A1F3FFF1FA07E998E86F7F7A27AE3“}”）；嵌套异常为

Answer 1

由于映射位于user的一侧(mappedby驻留在那里），您必须保存它才能看到填充到logincredential的更改。但您可以定义“父级”到“cascage”到“子级”中的更改：

@OneToOne(mappedBy = "loginCredential", fetch = FetchType.LAZY, cascade = CascadeType.ALL)

或者如果您不想将所有内容级联（例如删除）：

@OneToOne(mappedBy = "loginCredential", fetch = FetchType.LAZY, cascade = {CascadeType.PERSIST, CascadeType.MERGE})