Handling Profile Updates

We have a profile page with a form that allows logged in users to update their name. Now we need to add handling to ProfileServlet that will update the data store when the Save Changes button is clicked.

The trick is to know if the servlet is being called by clicking on a My Profile link, or as a result of the Save Changes button being clicked. The secret to that is to look at the form submission data provided to every servlet.

The HTTPServletRequest object (passed into the doPost and doGet methods by the web server) contains a method called getParameter. Pass it the name of a form element, and it will give you back the values associated with that element. If the element doesn't exist, you'll get null back.

So code like this:


if (req.getParameter("submit") == null)
{
// Servlet called because of link click
}
else
{
// Servlet called because of button click
}


will allow you to decide which situation is calling the servlet, so you can make the appropriate response.

In the case of the profile page, I still want to display the form after they click submit, but I want to update the data store, too. So I'm going to have code like this just after I fetch the user record from the data store, but just before I get any values out of it:


User user = results.get(0);

if (req.getParameter("submit") != null)
{
user.setName(req.getParameter("name").trim());
pm.makePersistent(user);
}

String name = user.getName ();



This completes the form processing round trip. We really should add some error checking and error messages, too. For example, someone shouldn't be able to save a blank name. Add appropriate error handling and messages to your own projects.

Following this same pattern, you can add however many profile fields you need. Just remember to add them to the User object, too, if they aren't already in there.