Question

My command object have a list of objects. I want to bind a text field to the attribute of the object inside that list. Is it possible to do in Spring MVC?

Command object class

public class SubDevisonDto {

private String devId;
private List subDevisions;

Subdevision object class mentioned in the list

public class SubDivison implements Serializable{

private String subDivisonName;
private String createdBy;
private String createdDate;
private String developerID;
private List users;

I want text box to set the value for subDivisonName field.

I have written the Spring MVC tags like this.

<spring:bind path="subdivisondto.subDevisions[0].subDivisonName">
    <span class="formw">
        <input name="subDivisonName" type="text" style="width:350px;" />
    </span>
</spring:bind>

Just for test purpose I have given it as 0. If it’s working I can make it to a variable. my requirement is, I should let the user to dynamically add subdevision objects. So, initially when page is loading I will just show one text box. I will give a button for him to add if he want to add more. I will dynamically generate text boxes when he clicks the add button. After that I have to submit the form with the list.

This jsp code gives me an error. It says:

org.springframework.beans.NullValueInNestedPathException

Is there anyway for me to do this in jsp code?

Answer 1

I found the answer for my question. But, it’s not the solution for my requirement as I need to implement a dynamic list. but I found a solution for this question.

As I understood, first time we have to send data from back end to bind input elements. I didn’t find a way to bind form elements which takes input without sending a list data from beck end. But when we send data and bind the elements, we can take input from those elements. So, I think to bind the element in a situation like this we need to send data first time. Correct me if this statement is wrong. Because, that would be a more good solution for me.

We need to use the lazy list and jsp code is bit modified.

Your command class object should be created as below mentioned.

import org.apache.commons.collections.list.LazyList;
import org.apache.commons.collections.FactoryUtils;



public class SubDevisonDto {

    private String devId;

    private List subDevisions = 
        LazyList.decorate(
          new ArrayList(),
          FactoryUtils.instantiateFactory(SubDivison.class));

JSP code should look like below.

<c:forEach items="${subs.subDevisions}" var="obj" varStatus="gridRow"> 

Binding an input element text box

<spring:bind path="subdivisondto.subDevisions[${gridRow.index}].subDivisonName">
      <span class="formw"><input name="<c:out value="${status.expression}"/>" type="text"  style="width:350px;" />

binding an input element check box. This input element makes a list.

<spring:bind path="subs.subDevisions[${gridRow.index}].users">
              <c:forEach items="${obj.users}" var="dependenttwo" varStatus="dependentRowtwo">
                <li>
                  <input name="<c:out value="${status.expression}"/>" type="checkbox" class="users" value="<c:out value="${dependenttwo}"/>"/>
                  <c:out value="${dependenttwo}"/>
                </li>
                </c:forEach>
                </spring:bind>

`subs` is a map key name. the value for this key `subs` is a list of my DTO objects which named as `SubDevisonDto `

This code works fine for me.

Thanks the support given.