List<Foo> as form backing object using Spring 3 MVC, correct syntax?

Question

I want to do something like this, where Foo is a class with one String field name, and getter/setter:

<form:form id="frmFoo" modelAttribute="foos">
   <c:forEach items="${foos}" var="foo">
     <form:input path="${foo.name}" type="text"/>

And then submit the complete list of Foos with updated names?

My controller looks like this:

@RequestMapping(value = "/FOO", method = RequestMethod.POST)
public String getSendEmail(List<Foo> foos, Model model) {
    // ...
}

Solution

Maybe this answersyour question:

CONTROLLER :

@Controller("/")
public class FooController{

    //returns the ModelAttribute fooListWrapper with the view fooForm
    @RequestMapping(value = "/FOO", method = RequestMethod.GET)
    public String getFooForm(Model model) {
        FooListWrapper fooListWrapper = new FooListWrapper();
        fooListWrapper.add(new Foo());
        fooListWrapper.add(new Foo());

        //add as many FOO you need

        model.addAttribute("fooListWrapper", fooListWrapper);

        return "fooForm";
    }

    @RequestMapping(value = "/FOO", method = RequestMethod.POST)
    public String postFooList(@ModelAttribute("fooListWrapper")FooListWrapper fooListWrapper, Model model) {

        //...........
    }

}

FOO LIST WRAPPER :

public class FooListWrapper {
    private List<Foo> fooList;

    public FooListWrapper() {
         this.fooList = new ArrayList<Foo>();
    }

    public List<Foo> getFooList() {
        return fooList;
    }

    public void setFooList(List<Foo> fooList) {
        this.fooList = fooList;
    }

    public void add(Foo foo) {
        this.fooList.add(foo);
    }
}

FOO CLASS :

public class Foo {
    private String name;

    public Foo() {
    }

    public String getName() {
        return name;
    }

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

JSP VIEW (name = fooForm):

<c:url var="fooUrl" value="/FOO"/>
<form:form id="frmFoo" action="${fooUrl}" method="POST" modelAttribute="fooListWrapper">


    <c:forEach items="${fooListWrapper.fooList}" varStatus="i">
           <form:input path="fooList[${i.index}].name" type="text"/>
    </c:forEach>


    <button>submit</button>
</form:form>

Comments

[littleK]

I assume that this solution requires having a fixed amount of input fields, is that correct? What if you have a dynamic number of input fields? For example, I have a requirement to let my users dynamically generate new input fields. Do you know how to handle that situation?

[w3bshark]

Faton, you're a life saver. Thanks a lot.

[newbie]

Faton, can you explain a bit why do you need to write a wrapper class?

[newbie]

I tried to follow this code but I'm getting Neither BindingResult nor plain target object for bean name 'com' available as request attribute error

[cmaduro]

How would you do this in Thymeleaf?

[Clemzd]

Is there a new solution with Spring 4? Because in this example it is needed to write "listwrapper" which is quite boring ^^

[Joel Peltonen]

Hey. What does <form:input path="fooList[${i.index}].name" type="text"/> look like rendered? I need to re-create it with javascript :)

[Joel Peltonen]

Oh, and by the way, see public String getFooList() { and public void setFooList(String fooList) { datatypes, they look very wrong, are they?

[sbsatter]

@Nenotlep, I don't understand what you meant with your first comment. Could you be more clear? And thank you for pointing that out, the answer has been edited. Btw. if you are asking what it looks like when viewed in a browser, it's simply the java way (correct me if I'm wrong) of the following: <input name="" type=""/>.

[Joel Peltonen]

Yes, that is what I meant; what does it look like to the browser. So the browser sees <input name="" type=""/>? Are the name and type empty?

[sbsatter]

Sorry for such a late reply, no they are not empty. type is text but the name and id both is the same as the value stored in fooList[0].name...fooList[n].name.