MVC Model 2 vs Spring SimpleFormController (Why formBackingObject() gets called twice?)

[nilu chan]

In traditional MVC Model 2 applications after the user submits the form we build the model object and populate bind the form values into the bean using a controller manually.

Whereas in Spring why do we build the model object when the user is shown the form and again while we submit the form. I put in a couple of System.outs in my spring controller and I could see the formBackingObject() getting called both the times. Does that mean that two model objects are created? One when the user is presented the form and one while the form is submitted?

Is the object passed to onSubmit() is the same instance as the one created by formBackingObject()?

Please guide.

[Tommy Delson]

I think in your xxx-servlet.xml configuration on the controller you redirect it to the same page where the form original submitted.

For example,
<property name="successView" value="redirect:/you_form_name.htm"/>
To solve the problem you need to redirect it to the page you want (i.e success.htm etc)

You know that "formBackingObject()" is called first when the page is loaded and "ModelAndView onSubmit()" is called next when you submit the form.

Post your codes might be help for trouble shooting if you still have not solve the problem...