null return value from getParameter (Tomcat Servlet)

Question

I am trying to get the value of a checkbox from a posted form data. I already have the form working because I can get the value of a file easily enough(I have omitted the file form field in the code below), but the checkbox wont return anything other than null. What am I doing wrong?

Servlet:

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { String str = request.getParameter("isTransform"); System.out.println("parameter: " + str); }

Html Client:

<form enctype="multipart/form-data" id="compareForm1" > <input type="checkbox" value="true" name="isTransform" id="isTransform1" > </form>

I have jquery.form.js sending the actual post

var options = { url: "http://localhost:8080/TestingTomcat/someClassName", type: "POST", success: function (html){ $("#placeholder").html(html); change_active("comparison_page"); } }; $("#compareForm1").submit(function () { $(this).ajaxSubmit(options); return false; });

Actual Post data:

POSTDATA =-----------------------------153501500631101 Content-Disposition: form-data; name="isTransform" true -----------------------------153501500631101 Content-Disposition: form-data; name="isTransform" true -----------------------------153501500631101--

And the result I get with the button clicked or unclicked is:

parameter: null

When it is ajax call don't you need to append the param& value to URL? Ajax calls are not full form submits. — kosa
– kosa, Commented Jul 10, 2012 at 20:45
I am relatively new to ajax... I had assumed since the file sent fine I should be able to do something simple like a check box in the same way — zanegray
– zanegray, Commented Jul 10, 2012 at 20:46
For simple test try this, localhost:8080/TestingTomcat/someClassName?isTransform=false in url section — kosa
– kosa, Commented Jul 10, 2012 at 20:48
Hey hey! It worked great but this leads me to another question. If I want to submit an entire form do I have to append it to the url? Shouldn't there be some way to encode it into a POST request? — zanegray
– zanegray, Commented Jul 10, 2012 at 20:51
Ajax submits partial form data (which you want to update). If you want full form, don't do ajax. — kosa
– kosa, Commented Jul 10, 2012 at 20:58

qrtt1 · Accepted Answer · 2012-07-10 20:56:00Z

Parameters post from 'multipart/form-data' form can not be get from getParameter method. You should use 3rd-party library to handle the multipart data for parse the content of req.getInputStream() by yourself. I think Apache Commons fileUpload will help you.

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