Question

I have a form that gets populated with data from the database.
Before is start describing my problem, some snippets:

One class:

// @Entity for areas
public class Area {
@Id
@Column(name = "area")
private String area;

@Column(name = "deleted")
private boolean deleted;

getter/setter
}

Second class

// @Entity for employees
public class Employee {
@Id
@GeneratedValue
@Column(name = "ID")
private long id;

@ManyToOne
@JoinColumn(name = "area")
private Area area;

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

getter/setter

The method in EmployeeController called to return data to the jsp

protected String createDialog( @PathVariable("id") Long id, Model model ){
    Employee employee = id == 0 ? new Employee() : employeeService.findById(id);
    //return employee
    model.addAttribute("employeeModel", employee );
 //add data needed to create dropdown holding areas
    //areaService.findAll returns a List<Area>
    model.addAttribute("areas", areaService.findAll( 
                new Sort( 
                    Sort.Direction.ASC,
                    "area"
                    )
                ));
    return "employees/dialogUpdateEdit";
}

The jsp, showing the dropdown for the areas and, if no new employee is returned, the known data

<form:form action="employees/ajax" commandName="employeeModel" method="POST" id="createForm">
    <table class="fullWidth">
        <tr>
            <td>Area</td>
            <td>
                <form:select path="area" items="${areas}" class="fullWidth">
                </form:select>
            </td>
        </tr>
        <tr>
            <td>Employee Name</td>
            <td><form:input path="name" class="fullWidth"/></td>
        </tr>
        <tr>
            <td colspan="2">
                <input type="submit" value="Save Changes" id="btnSaveEmployee" class="fullWidth" />
            </td>
        </tr>
    </table>

    <!-- adding hidden field to hold id on update -->
<form:hidden path="id" />   

</form:form>

The controller method doing validation and either returning some errors or not

@RequestMapping(value = "/ajax", method = RequestMethod.POST)
protected @ResponseBody ValidationResponse createOrUpdate(
        @Validated @ModelAttribute("employeeModel") Employee employee,
        BindingResult bindingResult) {

    if (!bindingResult.hasErrors()) {
        employeeService.createOrUpdate(employee);
    }

    return validate(employee, null, bindingResult);
}

For the problem:
This all works fine, dropdown is populated, data gets filled into the inputs.
But when I click the submit, I get the following error:

java.lang.IllegalStateException: Cannot convert value of type
[java.lang.String] to required type [com.whatever.Area] for property
‘area’: no matching editors or conversion strategy found

As far as I understand it, the form just submits the plain string for ‘area’ instead of binding the objects from the List.

How can I get the form to submit the object and not the string? is something wrong with my binding?

Thanks for your help!

Answer 1

To answer my own question and in the hope that the guy gets lot of credits who helped me without knowing 😉

I had to add a custom binder… Never heard of that before so I asked the long way first.

This link has the best and shortest tutorial on that subject I found since I knew what I was looking for:
http://empire5.com/development/binding-a-custom-object-in-spring-3/