Stripers,
I've run into a problem for which I found a simple but somewhat ugly
solution. I'm trying to find a more elegant solution that doesn't
increase complexity tenfold.
Consider a page with a list of people in a div id="people" and a form,
in the same page, in a div id="form". The form gets submitted via
AJAX. If no validation errors occur, the response is the fragment that
contains the refreshed list of people and should replace the "people" div.
Validation errors return the form, much like the standard Stripes
source page resolution except that it's just the form, not the entire
page. In that case, the response fragment should replace the "form"
div.
The problem consists of receiving the page fragment and deciding where
it should go: "people" or "form"? In other words, how would you
signal, in the response, a success/validatione error flag along with
the page fragment?
To be clear and save everyone time, allow me to enumerate some
solutions that do not satisfy my requirements:
- returning an HTTP error code. When validation errors occur, the HTTP
status is still successful and the page fragment is valid; it
contains the form with the validation errors.
- using JavaScriptResolution, JSON, XML data, etc. I do not want to
send raw data and have to rebuild the list of people or the form with
validation errors using JavaScript. That makes me feel like I'm back
in 1998, writing HTML code in Java Servlets. I want to send the page
fragments in the response, clean and simple.
- setting an HTTP response header. I tried this and correct me if I'm
wrong, but setting a response header and then returning a
ForwardResolution does not work. I've also had some difficulty
retrieving the response header in the AJAX callback function (with
jQuery). I should mention that I'm open to this solution but I haven't
found how to resolve these issues.
Right now I have an HTML comment in the list of people fragment. When
receiving the response data, finding that comment in the data means
success, and so put the fragment in "people". Otherwise, put the fragment
in "form". Like I said: simple, but ugly.
I also tried returning a JavaScriptResolution(url) upon success and
the form with validation errors upon failure. If eval(response) works,
I use the URL to refresh the list of people. This is similar to a
redirect. Not bad, but I have to do a try/catch on the call to eval()
because the HTML fragment with the form is obviously not valid
JavaScript. So I find this solution almost as brittle as the previous
one. If I return a JavaScriptResolution(true, url) on success and
JavaScriptResolution(false, url) upon failure, I'd have to submit the
form a second time, with some kind of indicator, to get the Stripes-
generated form with validation errors. Somewhat a steep price to pay
for elegance...
Ideally, I would love to be able to just return a JavaScriptResolution
(or JSON, whatever) with a simple Map:
{"success": true, "data": "(html fragment)"}
Then I could just check the flag to decide which div id to update with
the data. The HTML page fragment, however, would have to be generated
normally. That's the problem. I tried to executing a
ForwardResolution with an HttpServletResponseWrapper to capture the
output in a String, and put that in the JavaScriptResolution.
Surprisingly complicated, and it doesn't even work. Jetty complains of
an "already committed response" (even if I override isCommitted() to
return false) and Tomcat throws an InvalidStateException. Even if I
somehow got that to work, it feels like a hack-hack-ack-ack.
If you're still with me, it all boils down to: how to elegantly attach
some sort of additional data (in my case, a boolean flag) to a regular
Stripes Resolution?
Thanks in advance for any ideas on this.
Cheers,
Freddy
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