显示错误 HTTP 状态 500 - 请求处理失败； 嵌套异常是 org.hibernate.exception.ConstraintViolationException：

Question

我对 Spring MVC 项目有疑问。 我想将值插入到数据库中，但是当我单击提交按钮时显示错误 HTTP 状态 500 - 请求处理失败； 嵌套异常是 org.hibernate.exception.ConstraintViolationException：无法插入：[sample.entity.Details]

我不知道有什么问题。 请帮我？ 下面给出的程序

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
    <head>
        <title>Student Event Co-Ordinators/Organizer Details</title>
        <meta charset="UTF-8">
        <meta name="viewport" content="width=device-width, initial-scale=1.0">
               <link rel="stylesheet" href="//cdn.datatables.net/1.12.1/css/jquery.dataTables.min.css">
                      
<style>
body{
display: flex;
}
#submit
{
    background-color: orange;
    color:white;
    height: 30px;
        width:200px;
        border: none;
}
input[type=text] input[type=email] input[type=number]{
     transition: width 0.4s ease-in-out;
}
table {
  border-collapse: collapse;
  border: 1px solid black;
   table-layout: auto;
  width: 100%;  
} 

th,td {
  border: 1px solid black;
  width:16%
}
.btn {
  border: none;
  background-color: inherit;
  padding: 14px 28px;
  font-size: 16px;
  cursor: pointer;
  display: inline-block;
}
.btn-add
{
    background-color: orange;
    color:white;
    height: 40px;
        width:200px;
        border: none;
        font-size: 12px;
}
/* On mouse-over */
.btn:hover {background: #eee;}

.btn-warning {color: orange;}
.btn-danger {color: red;}
.btn-info{
    color:blue;
}

         </style>

    </head>
    <body>
        <div class="container">
        <h3>Student Event Co-Ordinators/Organizer Details</h3>
       
        <form id="studentevent" name="studentevent" action="/index.htm" method="post">     
                <input type="hidden" id="id" name="id" >
                         <div> 
                    <div>
                          <input type="text"  placeholder="Event name"  name="name" required="" id="name">                    
                          <input type="email"  placeholder="Event email id"  name="email" required="" id="email"> 
                          <input type="number"  placeholder="Registration fee"  name="fee" required="" id="fee">  
                          <input type="text"  placeholder="Student name"  name="sname" required="" id="sname">  
                          <input type="number"  placeholder="Student contact no"  name="contactno" required="" id="contactno">  
                   </div>
        <br>
        <div>
            <input type="button" id="submit" value="submit" onclick="return addstudentevent();">
                   </form>
        <br>
        <br>
                 <table class="data-table" id="data-table">
                <thead>
                    <th>Event Name</th>
                    <th>Email Id</th>
                    <th>Registration Fee</th>
                    <th>Student Name</th>
                    <th>Contact No</th>
                    <th> </th>
                </thead>
                <tbody id="displayBody">
                    
</tbody>
            </table>
        </div>
        </div>

         
          <script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>
        <script src="https://cdn.datatables.net/1.10.24/js/jquery.dataTables.min.js" type="text/javascript"></script>
        
        <script>
        
                     getall();
                        var isNew = true;
                    var    studentid= null;
                
                        function addstudentevent()
                        {
                                var addId = $("#id").val();
                                 var url = "";
                                var data = "";
                                var method;
                                if (isNew===true)
                                    {
                                        url = 'insert.htm';
                                        data = $("#studentevent").serialize()+ "&Id=" + addId;
                                        method = 'POST';
                                    }
                               else
                                    {
                                        url = 'update.htm';
                                        data = $("#studentevent").serialize()  + "&Id=" + addId;
                                        method = 'POST';
                                    }
                                    $.ajax({
                                        type: method,
                                        url : url,
                                       dataType: 'JSON',
                                        data : data,
                                        
                                        success:function(data)
                                        {
                                         getall();
                                           // $('id').val("");
                                           $('#name').val("");
                                            $('#email').val("");
                                            $('#fee').val("");
                                            $('#sname').val("");
                                            $('#contactno').val("");
                                            
                                                if(isNew === true)
                                                    {
                                                        alert("Data Inserted");
                                                    }
                                 else
                                                    {
                                                        alert("Data Updated");
                                                    }
                                            }
                                    });
                            }
                        
                        

function getall()
{
    $('#data-table').dataTable().fnDestroy();
                            $.ajax ({
                                url: "fetch.htm",
                                type: "GET",
                                dataType:"JSON",
                                
                                success: function(data)
                                {
                                    $("#data-table").dataTable({
                                        "aaData":data,
                           "scrollX": true,
                           "aoColumns":
                                   [
                     
                                 {"mData": "name"},
                                    {"mData": "email"},
                                    {"mData": "fee"},
                                    {"mData": "sname"},    
                                     {"mData": "contactno"}   ,                                                      
                                     {               //   " mData": "id",  
                                                  mData:"id",
                                                        "render" : function(mData,type,row,meta)
                                                        {
                                                            return '<button class="btn btn-warning" onclick="get_details('+ mData +')">Edit</button><button class="btn btn-danger" onclick="get_delete('+ mData +')">Delete</button>';
                                                        }}                                                
                                   ]   
                               });     }   
                                });
                            }
   
                        
                        function get_details(id)
                        {
                            $.ajax({
                                type: "POST",
                                url: "edit.htm",
                                data: {"id": id},
                                
                                success: function(data)
                                {
                                    isNew = false;
                                    var obj = JSON.parse(data);
                                      studentid = obj[0].id;
                                    $('#name').val(obj[0].name);
                                    $('#email').val(obj[0].email);
                                    $('#fee').val(obj[0].fee);
                                        $('#sname').val(obj[0].sname);
                                            $('#contactno').val(obj[0].contactno);
                                                                   }
                            });
                        }
                 
                        function get_delete(id)
                        {
                            $.ajax({
                                type:'POST',
                                url: 'delete.htm',
                                dataType: 'JSON',
                                data:{'id':id},
                                
                                success:function (data)
                                {
                                    alert("Data deleted");
                                   getall();
                                }
                            });
                        }

    </script>

    </body>
</html>

学生控制器.java

package sample.controller;

import com.google.gson.Gson;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.ResponseBody;
import sample.dao.studentDao;
import sample.entity.Details;


/**
 *
 * @author admin
 */

@Controller
public class studentController {
      @Autowired
    studentDao stDao;
     @RequestMapping(value ="index.htm", method = RequestMethod.GET)
    public String index()
    {
        System.out.println("at index");
        return "index";
    }
    
    @RequestMapping(value ="insert.htm", method = RequestMethod.POST)
    public @ResponseBody String insert
        (
            @RequestParam("id") Integer id,
            @RequestParam("name") String name,
            @RequestParam("email") String email,
            @RequestParam("fee") String fee,
              @RequestParam("sname") String sname,
              @RequestParam("contactno") String contactno
        )
  
        {

        Details ei= new Details();
        ei.setName(name);
        ei.setEmail(email);
        ei.setFee(fee);
        ei.setSname(sname);
        ei.setContactno(contactno);
        
        stDao.save(ei);
        
        Gson ob = new Gson();
        return "success";
   }
    
 @RequestMapping(value="fetch.htm", method = RequestMethod.GET)
    public @ResponseBody String display() 
    {
        List<Details> listdetails = (List<Details>) stDao.display();
        return new Gson().toJson(listdetails);
    }

    
    @RequestMapping(value = "delete.htm")
    public @ResponseBody  String delete(@RequestParam("id") Integer id)
    {
        stDao.delete(id);
        return "successful";
    }
    
    @RequestMapping(value = "edit.htm")
    public @ResponseBody  String edit(@RequestParam("id") Integer id)
    {
        List editlist;
        editlist = stDao.getDetailsForEdit(id);
        return new Gson().toJson(editlist);
    }
    
    
    @RequestMapping(value = "update.htm", method = RequestMethod.POST)
    public @ResponseBody String update
        (
            @RequestParam(value="id",required=false) Integer id,
            @RequestParam("name") String name,
            @RequestParam("email") String email,
            @RequestParam("fee") String fee,
            @RequestParam("sname") String sname,
            @RequestParam("contactno") String contactno
       )
        {
            
        Details st = new Details();
        st.setName(name);
        st.setEmail(email);
        st.setFee(fee);
        st.setSname(sname);
        st.setContactno(contactno);
        System.out.println("st");
        stDao.update(st);
        Gson ob = new Gson();
        return "success";
    }

}

学生道.java

package sample.dao;

import java.util.List;
import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.criterion.Projections;
import org.hibernate.criterion.Restrictions;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;
import org.springframework.transaction.annotation.Transactional;
import sample.entity.Details;


/**
 *
 * @author admin
 */
@Transactional
@Repository
public class studentDao {

   @Autowired
    private SessionFactory sessionFactory;


    public void save(Details stdinfo) {
        Session session = sessionFactory.openSession();
        session.save(stdinfo);
        session.close();
    }
public List display() {
        Session session = sessionFactory.openSession();
        Criteria criteria = session.createCriteria(Details.class);
        criteria.setProjection(Projections.projectionList().add(Projections.property("id"), "id")
                .add(Projections.property("name"), "name")
                .add(Projections.property("email"), "email")
                .add(Projections.property("fee"), "fee") 
                .add(Projections.property("sname"), "sname") 
                .add(Projections.property("contactno"), "contactno"));
        criteria.setResultTransformer(Criteria.ALIAS_TO_ENTITY_MAP);
        List list = criteria.list();
        session.close();
        return list;
    }

    
     public void delete(Integer id){
        Session session = sessionFactory.openSession();
        Transaction trx = session.beginTransaction();
        Details stdtl = new Details(id);
        session.delete(stdtl);
        trx.commit();
        session.close();
    }
  
     
     
     public List getDetailsForEdit(Integer id) {
        Session session = sessionFactory.openSession();
        Criteria criteria = session.createCriteria(Details.class);
        criteria.setProjection(Projections.projectionList()
                .add(Projections.property("id"), "id")
                .add(Projections.property("name"), "name")
                .add(Projections.property("email"), "email")
                       .add(Projections.property("fee"), "fee")
                       .add(Projections.property("sname"), "sname")
                .add(Projections.property("contactno"), "contactno")
        );
        criteria.add(Restrictions.eq("id", id));
        criteria.setResultTransformer(Criteria.ALIAS_TO_ENTITY_MAP);
        List list = criteria.list();
        session.close();
        return list;
    }

    public void update(Details Stdinfo){
        Session session = sessionFactory.openSession();
        Transaction trx = session.beginTransaction();
        
        session.update(Stdinfo);
        trx.commit();
        session.close();
    }
   
   
}

详情.java

package sample.entity;

import java.io.Serializable;
import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;
import org.hibernate.annotations.NamedQueries;
import org.hibernate.annotations.NamedQuery;

/**
 *
 * @author admin
 */
@Entity
@Table(name = "studentevent")
@NamedQueries({
    @NamedQuery(name = "studentevent.findAll", query = "SELECT d FROM studentevent d")})
public class Details implements Serializable {

    private static final long serialVersionUID = 1L;
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Basic(optional = false)
    @Column(name = "id")
    private Integer id;
    @Column(name = "name")
    private String[] name;
    @Column(name = "email")
    private String mail;
       @Column(name = "fee")
    private String fee;
   @Column(name = "sname")
    private String sname;
    @Column(name = "contactno")
 private String contactno;
   
   
   
   
    public Details() {
    }

    public Details(Integer id) {
        this.id = id;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String[] getName() {
        return name;
    }

    public void setName(String stdname) {
        this.name = name;
    }

    public String getEmail() {
        String email = null;
        return email;
    }

    public void setEmail(String email) {
        this.mail = email;
    }

     public String getFee() {
        String fee = null;
        return fee;
    }

    public void setFee(String fee) {
        this.fee= fee;
    }
     public String getSname() {
        String sname = null;
        return sname;
    }

    public void setSname(String sname) {
        this.sname= sname;
    }
    public String getContactno() {
        return contactno;
    }

    public void setContactno(String contactno) {
        this.contactno = contactno;
    }

   }

Answer 1

正如@Lalit Mehra 在评论中提到的那样，HTML 正在发送 POST 请求，而 controller 正在等待 GET：

<form id="studentevent" name="studentevent" action="/index.htm" method="post">     

@RequestMapping(value ="index.htm", method = RequestMethod.GET)

使它们与相同的请求方法匹配，它将起作用。