Java 通过Spring Boot中的POST创建对父实体的引用

我目前正在尝试用Spring Boot构建一个RESTAPI，它支持客户端和作业。客户机可以有许多作业，而作业属于客户机。但是，当我通过客户端id或试图查找客户端对象保存引用客户端的作业时，会出现以下错误：

{
  "timestamp" : 1479163164739,
  "status" : 400,
  "error" : "Bad Request",
  "exception" : "org.springframework.http.converter.HttpMessageNotReadableException",
  "message" : "Could not read document: Can not construct instance of com.core.model.Client: no String-argument constructor/factory method to deserialize from String value ('3')\n at [Source: java.io.PushbackInputStream@5138cca1; line: 1, column: 12] (through reference chain: com.core.model.Job[\"client\"]); nested exception is com.fasterxml.jackson.databind.JsonMappingException: Can not construct instance of com.core.model.Client: no String-argument constructor/factory method to deserialize from String value ('3')\n at [Source: java.io.PushbackInputStream@5138cca1; line: 1, column: 12] (through reference chain: com.core.model.Job[\"client\"])",
  "path" : "/api/v1/jobs"
}

包括我的作业和客户端模型和控制器：

我的工作模式：

package com.core.model;

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.CascadeType;
import javax.persistence.Table;
import javax.persistence.Column;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Id;

@Entity
@Table(name="`job`")
public class Job {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name="job_id")
    private Long jobId;

    @ManyToOne(cascade=CascadeType.ALL, targetEntity = Client.class)
    @JoinColumn(name = "client_id", nullable = false)
    private Client client;

    private String address1;
    private String address2;
    private String city;
    private String county;
    private String state;
    private String zip;
    private String country;
    private String description;

    //Note: I tried Long client_id instead of using the Client object here and same thing
    public Job(String description, String address1, String address2, String city, String county,
               String state, String zip, String country, Client client) {
        this.setDescription(description);
        this.setAddress1(address1);
        this.setAddress2(address2);
        ...
        this.setClient(client);
    }

    public Job() {}

    public Long getId() { return jobId; }
    public void setId(Long id) { this.jobId = id; }
    ...
    public Client getClient() { return client; }
    public void setClient(Client client) { this.client = client; }

}

作业的控制器：

package com.core.controller;

import com.core.model.Job;
import com.core.repository.JobRepository;
import org.apache.catalina.connector.Response;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;
import com.core.repository.JobRepository;
import org.springframework.hateoas.Resource;

import java.util.Collection;
import java.util.List;

@RestController
@RequestMapping("/api/v1/jobs")
public class JobController {

    @Autowired
    private JobRepository repository;

    @RequestMapping(method = RequestMethod.GET)
    public ResponseEntity<Collection<Job>> getAllJob(){
        return new ResponseEntity<>((Collection<Job>) repository.findAll(), HttpStatus.OK);
    }
    @RequestMapping(method = RequestMethod.GET, value = "/{id}")
    public ResponseEntity<Job> getEquipmentWithId(@PathVariable Long id) {
        return new ResponseEntity<>(repository.findOne(id),HttpStatus.OK);
    }

    @RequestMapping(value="", method=RequestMethod.POST)
    public ResponseEntity createNew(@RequestBody Job job) {
        repository.save(job);
        return new ResponseEntity(job, HttpStatus.CREATED);
    }
}

---

我只想将客户id保存到作业中，这里的正确方法是什么

我猜您正在尝试使用REST调用此方法：

@RequestMapping(value="", method=RequestMethod.POST)
public ResponseEntity createNew(@RequestBody Job job) {
        repository.save(job);
        return new ResponseEntity(job, HttpStatus.CREATED);
}

这个例外非常清楚，它谈到：

com.fasterxml.jackson.databind.JsonMappingException

这意味着，每当您试图在请求主体内传递作业实体时，Jackson都无法将其绑定到方法控制器上的

作业

参数

我的建议是尝试编写Jackson反序列化器类，它将告诉Jackson如何进行反序列化

下面是一个如何执行此操作的示例：

---

你能展示一下你的要求吗。因此，我为作业实体创建了一个反序列化器和序列化器，我能够获取客户机id的值，就像该示例所做的那样。我想我的问题是：从这里开始，我应该用一个（长的）client_id实例化一个新的作业对象并尝试以这种方式保存它（并且只使用client_id作为成员而不是client对象），还是应该实例化一个client对象，尝试找到传递了id的对象，然后做点什么，给客户增加一份新的工作？我选择了后者，效果不错！刚到春天，来自一个不同的世界，非常感谢你的帮助！干杯；-）没问题

com.fasterxml.jackson.databind.JsonMappingException