Unique Display Names

I'm going to focus on new techniques in the coming posts, because the semester is starting.

I've decided to make display names unique in the system. I'm not especially happy with this, since it leads to funky display names like Dave5386. But, if I'm going to provide some sort of forum interaction eventually, I also need a way to differentiate between people who might decide to use the same display name.

I could simply require and display some context to the display name, such as "Jay, Muskingum University". But, providing information online for kids that might be used to locate them is not a good idea.

So, I'll go with unique display names. This means I need to change what I already have a bit.

RPXResults.java is what first puts the user into the datastore. Right now it's getting the user name from the RPX records. That isn't guaranteed to be unique. I could auto-generate a unique name, but then they might not go back and edit it.

So instead, RPXResults.java will, when a user logs in for the first time, redirect to the page for editing their profile. They will be required to update their profile with a unique name before doing using the rest of the site as a logged in user.

While I'm at it, I also want to modify RPXResults.java so that instead of redirecting to /front when a user logs in and they do have their profile info set, it redirects to the page they were trying to access. So if they save a bookmark on My Contests, and try to go to that after the session has expired, it'll take them to the login page and then to My Contests after they log in. That's more user-friendly, and best to do now before I have too many of those sorts of pages to edit.

Redirect to Target Page

We'll do the redirect to the target page first. This requires me to pass into /rpxresults the target page. Here's a page at RPXNow about passing query parameters through the token URL.

Unfortunately, that didn't work for me. The extra query parameter simply never came through to RPXResults.java.

Luckily we do have another option. We can store the destination URL as a cookie on the local machine and fetch it from RPXResults.java.

We'll do FrontPage.java first as an example of how to modify the servlets. Here's the code to save the destination URL as a cookie:


Cookie cookie = new Cookie ("destinationURL", "/front");
resp.addCookie(cookie);


I added this to just before the template is displayed. Now we need to modify RPXResults.java to use the value of this cookie as the destination URL. Here's the code that would replace the resp.redirect ("/front") line:


String destination = null;
Cookie [] cookies = req.getCookies();

if (destination == null && cookies != null)
{
for(int i=0; i<cookies.length; i++)
{
Cookie cookie = cookies[i];

if ("destinationURL".equals(cookie.getName()))
destination = cookie.getValue();
}
}

if (destination == null)
destination = "/front";

resp.sendRedirect(destination);


Now that RPXResults.java is set up, I can go back and modify the ProfileServlet and AdminServlet classes to add the cookie in the same way that the FrontPage servlet does.

Now if I remember to do that for every servlet I add after this, the user will always get to the page they wanted to get to, even if they have to log in first.

That's probably long enough for one post, so I'll do unique user names in the next.