Spring form tags. Allow nulls in form:select (enum) - spring

Question

I'm using Spring form tags for filling form with values.
I have form backing object:
public class FormInfo {
public enum Status {ON, OFF}
private Satus status;
//getter setter
...
}
And in JSP Status enum presented like this:
<form:form commandObject="formInfo " ...>
<form:select path="status">
<form:option value="null" label="Please select"/>
<form:options/>
</form:select>
</form:form>
All works fine, i.e. default message and enum values are presented in <select>.
But the status field is not required, so I want allow user to leave Status field unselected. But if form submitted without selecting status field, then I get error:
error in object 'formInfo' on field 'status': rejected value [null];
How I can set enum to null when no values is selected?
Please note I'm using JSR 303 validation. And error described above is not happens automatically, I get this error message manually from following method BindingResult#getFieldErrors().
This is my controller code:
public void myMethod(#Valid #ModelAttribute("formInfo") FormInfo sourcingDetail, BindingResult bindingResult) {
if (bindingResult.hasErrors()) {
log.error("Error during validation is occurred." + bindingResult.getFieldErrors().toString()); // <-- this is error message
}
...
}
Also please note, I didn't set any JSR-303 annotation (like #NotNull) on status field.
UPDATE:
Almost full error message which I get from calling this method BindingResult#getFieldErrors() (explained above):
Error during validation is occurred.[Field error in object 'formInfo'
on field 'status': rejected value [null];
...
[Failed to convert property value of type 'java.lang.String' to
required type 'com.my.project.model.Status' for property 'status';
nested exception is java.lang.IllegalStateException: Cannot convert
value of type [java.lang.String] to required type
[com.my.project.model.Status] for property 'status': no matching
editors or conversion strategy found],

Answer 1

Looks like you have the same problem as i!.
There is a method in the controller that serves as a hook where you could specify how to transform the String values, that came from the HTTP request, to a concrete object!.
The method is called initBinder, and there you attach the right behavior to do the conversion properly. I am still researching, but so far, looks good.
Take a look at this :
Form Values to be Null instead of "" in Spring
http://kaushalyas.blogspot.com.ar/2011/02/data-binding-in-spring-mvc.html
Hope it helps to found the solution!
Greetings
Victor.