Question

in My jsp I am using spring form tags to bind and update data.

my scenario is to show default values when user enters the page. these default values should come from database depending on some conditions.
But when user edits the data and submit, I want to save them in databse without updating the default values.

Any suggestion is greatly appreciated!

Answer 1

Standard approach to a form page is to have a controller with two methods, one for GET and one for POST. You’ll also need an object to bind to the form.

The method that handles the GET sets up the bind object and puts it in the model, then returns the view for the form page. The bind object here can be created with default values which you can get from anywhere. Your bind object will probably have some key, like an ID. The default one can have a zero/default key.

The method that handles the POST takes the bind object as a parameter. It probably validates the values then inserts into the database. Its likely the database will generate the key/id.

Here’s an example;

@Controller
public class PersonController {

  @RequestMapping(value="/person.do", method=RequestMethod.GET)
  public ModelAndView setup() {
    ModelAndView response = new ModelAndView("person");

    //Create default bind object, can get values
    //from database if you like. Here they're just
    //hard coded.
    Person person = new Person();
    person.setName("Joe Bloggs");

    response.addObject("person", person);
    return response;
  }

  @RequestMapping(value="/person.do", method=RequestMethod.POST)
  public ModelAndView post(@ModelAttribute("person") Person person,
                           BindingResult result) {
    Validator.validate(person, result);
    if (result.hasErrors()) {
      ModelAndView response = new ModelAndView("person");
      response.addObject("person", person);
      return response;
    } else {
      personDao.store(person);
    }

    return new ModelAndView("redirect:nextPage.do");
  }

}