Populate form using values getting from Spring Controller

Question

I am simply creating a CRUD Application in Spring MVC. I want to edit Student Details. I have created one form which is used to add student. How can I use the same form to populate the student details for editing it ?

Controller

@RequestMapping(value="/add", method = RequestMethod.GET)
public String addStudent(@RequestParam("studentName") String name,@RequestParam("studentId") String studId){
    System.out.println("Student Id : "+ studId);
    System.out.println("Student "+name+" added");
    list.add(name);
    return "redirect:get";
}

@RequestMapping(value="/edit/${index}", method = RequestMethod.GET)
public String editStudent(@PathVariable("index") int index, Model model){
    System.out.println("Edit Student with Index " + index);
    model.addAttribute("studentId",index);
    model.addAttribute("studentName",list.get(index));
    return "student";
}

Form

<c:url value="/students/add" var="addStudentAction"></c:url>
<form action="${addStudentAction}" method="get">
    <input type="hidden" name="studentId">
    <input type="text" name="studentName"></input>
    <input type="submit" name="submit" value="Add Student" />
</form>

I want to set studentId and studentName in form fields which are set in model in editStudent method.

Just for your information: for creating and editing it's much better to use POST method instead of GET. — Slava Semushin, Jan 18 '17 at 11:26
The key is the usage of modelAttribute. Have a look here for instance http://www.arquitecturajava.com/spring-mvc-modelattribute/ — kimy82, Jan 18 '17 at 11:30

score 1 · Accepted Answer · answered Jan 18 '17 at 11:36

1

What you're asking is a very basic question that ideally should be learned from the tutorials and documentation.

Here is a short list of the steps:

use Spring tags for rendering form (<form:form>, <form:input>, etc)
create an object that will represent form values and export it from the controller to the view
take this object as an argument in the controller's method that is handling form submission

answered Jan 18 '17 at 11:36

Slava Semushin

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using spring form it is mandatory to speicfy model in the modelAttribute. I don't want to create my custom model class. – Harsh Kanakhara Jan 18 '17 at 12:00
In this case you have to fill `value` attributes manually: `` – Slava Semushin Jan 18 '17 at 12:12

score 0 · Answer 2 · edited Jan 18 '17 at 16:52

I think you need two pages and one controller.
1. for list all students : index.jsp

    <%@ page contentType="text/html;charset=UTF-8" language="java" %>
    <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
    <html>
    <head>
        <title>Title</title>
    </head>
    <body>
    <h3>Student List</h3>
    <div>
        <p>
        <ul>
            <c:forEach items="${requestScope.students}" var="student">
                <li>
                    <c:out value="${student.id}"></c:out> |
                    <c:out value="${student.name}"></c:out> |
                    <a href="${pageContext.request.contextPath}/student/<c:out value='${student.id}'/>">edit</a>
                </li>
            </c:forEach>
        </ul>
        </p>
        <p><a href="${pageContext.request.contextPath}/student/new">Create Student</a></p>
    </div>
    </body>
    </html>

for show or edit or create student: edit.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<c:if test="${student.id == null}">
    <h3>Student Create</h3>
</c:if>
<c:if test="${student.id != null}">
    <h3>Student Edit</h3>
</c:if>
<div>
    <form action="${pageContext.request.contextPath}/student/" method="post">
        <input type="hidden" name="id" value="<c:out value='${student.id}'/>"/>
        <p>Student Name: <input type="text" name="name" value="<c:out value='${student.name}'/>"></p>
        <p><input type="submit" value="submit"/></p>
    </form>
</div>
</body>
</html>

student controller

package cn.kolbe.student;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;
import org.springframework.web.servlet.ModelAndView;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.ConcurrentHashMap;
@Controller
@RequestMapping("/student")
public class StudentController {
    @GetMapping("")
    public ModelAndView index() {
        List<Student> students = new ArrayList<Student>();
        studentCache.keySet().forEach(id -> {
            students.add(studentCache.get(id));
        });
        return new ModelAndView("student/index", "students", students);
    }
    @GetMapping("/{id}")
    public ModelAndView show(@PathVariable("id")String id) {
        if (id.equals("new")) {
            return new ModelAndView("student/edit");
        } else {
            Student student = studentCache.get(Long.valueOf(id));
            return new ModelAndView("student/edit", "student", student);
        }
    }
    @PostMapping("")
    public String createOrEdit(String name, Long id) {
        Student student;
        if (id == null) {
            id = cacheId++;
            student = new Student(id, name);
            studentCache.put(id, student);
        } else {
            student = studentCache.get(id);
            student.setName(name);
        }
        return "redirect:/student";
    }
    private static ConcurrentHashMap<Long, Student> studentCache = new ConcurrentHashMap<>();
    private static Long cacheId = 1L;
}

I believe that using scriptlets is a bad style and I would rather use `` instead. — Slava Semushin, Jan 18 '17 at 14:28
Another possible issue here related to concurrency: because controller is a bean and by default it has `singleton` scope then it's possible that 2 and more threads will execute methods on the controller. Consider using `ConcurrentHashMap` instead of `HashMap`. — Slava Semushin, Jan 18 '17 at 14:31
Another possible problem: using `${student.id}` in the HTML code is prone to XSS attacks. Consider using `` which escapes data before printing. — Slava Semushin, Jan 18 '17 at 14:35
Hi Slava Semushin ,I agree with you. And edit the code already. Thank you! — Kolbe, Jan 18 '17 at 16:03
Yet another issue is to replace `Long` by `AtomicLong` (http://stackoverflow.com/questions/35546956/what-is-atomiclong-in-java-used-for). — Slava Semushin, Jan 18 '17 at 16:54

score 0 · Answer 3 · edited Feb 09 '19 at 19:23

0

Don't use html <form> tag.

Use Spring tags for rendering form that is <form:form> ,<form:input>

edited Feb 09 '19 at 19:23

Oliver

1,218
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answered Feb 09 '19 at 13:56

Sid

1
1

Welcome to Stack Overflow! Next time, please leave the unnecessarily formatting out of your answer, such as using capital and/or bold letters excessively. Highlight only your single most important sentence or points. – Oliver Feb 09 '19 at 19:36

Populate form using values getting from Spring Controller

3 Answers3