Question

我在弹簧输入表单中传递对象（CarType）有问题。

我的车型：

@Entity
@Table(name="CAR")
public class Car implements Serializable{

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    @Column(name = "CAR_ID", unique=true, nullable=false)
    private long id;

    @NotEmpty
    @Column(name = "REG_NO", nullable=false)
    private String regNo;

    @NotEmpty
    @Column(name = "YEAR", nullable=false, length = 4)
    private String year;

    @Column(name = "AVAILABLE", nullable=false)
    private boolean available = true;

    @Column(name = "START_DATE")
    private String startDate;

    @Column(name = "RETURN_DATE")
    private String returnDate;

    @OneToOne
    @JoinColumn(name="CAR_TYPE_ID")
    private CarType carType;

//getters and setters

车型型号：

 @Entity
    @Table(name = "CAR_TYPE")
    public class CarType {

        @Id
        @GeneratedValue(strategy=GenerationType.IDENTITY)
        @Column(name = "CAR_TYPE_ID", unique=true, nullable=false)
        private int id;

        @NotEmpty
        @Column(name = "MARK", nullable=false)
        private String mark;

        @NotEmpty
        @Column(name = "MODEL", nullable=false)
        private String model;

//getters and setters

控制器：

@RequestMapping(value = { "/rent-car-{regNo}" }, method = RequestMethod.GET)
    public String rentCar(@PathVariable String regNo, ModelMap model) {
        Car car = carService.findCarByRegNo(regNo);
        model.addAttribute("car", car);
        return "rentcar";
    }

    @RequestMapping(value = { "/rent-car-{regNo}" }, method = RequestMethod.POST)
    public String saveRentCar(@Valid Car car,  BindingResult result, ModelMap model) {
        carService.updateCar(car);
        model.addAttribute("success", "Car " + car.getRegNo() + " rented successfully");
        return "registrationsuccess";
    }

JSP文件

<form:form method="POST" modelAttribute="car" class="form-horizontal">
                <form:input type="hidden" path="id" id="id"/>
                <form:input type="hidden" path="year" id="year"/>
                <form:input type="hidden" path="regNo" id="regNo"/>
                <form:input type="hidden" path="available" id="available"/>
                <form:input type="hidden" path="carType" id="carType"/>
 <form:input type="text" path="startDate" id="startDate"/>
<form:input type="text" path="returnDate" id="returnDate"/>

我的代码有问题

<form:input type="hidden" path="carType" id="carType"/>

如何将对象CarType传递给Car表单？我总是有同样的错误：列＆＃39; CAR_TYPE_ID＆＃39;不能为空。看起来我将空CarType转移到Car。我不知道为什么？有人可以帮帮我吗？在registercar.jsp中，我使用了转换器（将regNo转换为类CarType）及其工作原理。

Answer 1

您需要知道Car对象如何从来自客户端的http请求绑定到Controller处理程序方法中。 Spring MVC映射请求参数以构造Car对象。因此CarType是一个关联的对象。你需要为Spring MVC提供一个最小的线索，为你构建它。

  <form:form method="POST" action="/rent-car${regNo}" modelAttribute="car">
       ......
       <form:input type="hidden" path="carType.id"/>
       <form:input type="hidden" path="carType.model"/>
       <form:input type="hidden" path="carType.mark"/>

       <input type="submit" value="Submit"/>
  </form:form>

你会在这篇文章Spring MVC - Binding Request Parameters and Path Variables to Java Backing Objects

中找到一个补充例子

以弹簧形式传递对象输入隐藏的SpringMVC

1 个答案: