Javascript adding hidden data to form

Question

I've the following Javascript function to add invisible data into my form,

function addHidden(theForm, key, value) {
var input = document.createElement('input');
input.type = 'hidden';
input.name = key;'name-as-seen-at-the-server';
input.value = value;
theForm.appendChild(input);
}

and I have two forms as follows

form1

<form method="get" id="execform" name="toexecute" enctype="multipart/form-data">
    <div id="to execute">
        <ul id=ul>
            <li><button type= "button" id="execute1" onclick="saveTextAsFile()">Click to execute</button></li><li><br></li>
        </ul>
    </div>  
</form>

saveTextAsFile()

var script = ace.edit("editor");
var myDivText = script.getValue();
var theForm = document.forms['toexecute'];
addHidden(theForm, 'mytxt', myDivText);
document.toexecute.submit();

form2

<form method="post" id="theform" name="myform" action="upload" enctype="multipart/form-data">
    <div id="elements">
    <ul id="ul">
        <li>Left File : <input type="file" name="dataFile1" id="fileChooser1" /></li><li><br></li>
        <li>Right File : <input type="file" name="dataFile2" id="fileChooser2" /></li><li><br></li>
        <li>Runner.xlsx : <input type="file" name="dataFile3" id="fileChooser3" /></li><li><br></li>
        <li><button type="button" id="execute" onclick="ValidateFile()">Click to Upload files</button></li>
    </ul>
    </div>
</form>

ValidateFile()

var myDivText1 = ace.edit("editor").getValue();
var theForm1 = document.forms['myform'];
addHidden(theForm1, 'mytxt1', myDivText1);
alert(myDivText1);
document.myform.submit();   

The hidden data of form 1 is being successfully added, passed and I am able to access that in my servlet, while I've used the same method in form 2 my servlet is throwing a nullpointerexception. What is my mistake?

When form2 is being submitted in my servlet,

protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException 
{//activated by the form named myform of line 93 in geco.jsp
    PrintWriter out = response.getWriter();

    Cookie[] cookies = request.getCookies();
    String fpath= null;
    if (cookies != null) {//Get cookie initilised when user uploads geco script
     for (Cookie cookie : cookies) {
       if (cookie.getName().equals("thecookie")) { 
           fpath = cookie.getValue();
        }
      }
    }

    response.setContentType("text/html");  

        FileItemFactory factory = new DiskFileItemFactory();  
        ServletFileUpload upload = new ServletFileUpload(factory);
        try 
        {  
            List items = upload.parseRequest(request);  
            Iterator iterator = items.iterator();
            while (iterator.hasNext())
            {  
                FileItem item = (FileItem) iterator.next();  
                if (!item.isFormField())  
                {
                    String fileName = item.getName();      

                         String itemField = item.getFieldName();

                         if (itemField.equals("dataFile1")) 
                         {  //get the text of the editor here and save it

                            String TEXT = request.getAttribute("mytxt1").toString();//This is where it is displaying null


                            File uploadedFile = new File(fpath, fileName);
                            item.write(uploadedFile);
                            String f1 = "<span class='blue'>" + "Uploaded <b>left file</b> " +fileName+ "<br>" + "</span>";
                            request.setAttribute("f1stat", f1);
                         }
                         if (itemField.equals("dataFile2"))
                         {    
                            File uploadedFile = new File(fpath, fileName);
                            item.write(uploadedFile);
                            String f2 = "<span class='blue'>" +"Uploaded <b>right file</b> " +fileName+ "<br>" + "</span>";

                            request.setAttribute("f2stat", f2);
                         }
                         if (itemField.equals("dataFile3"))
                         {
                             File uploadedFile = new File(fpath, fileName);
                             item.write(uploadedFile);
                             File uploadedFile1 = new File(fpath, "Runner.xlsx");
                             item.write(uploadedFile1);
                             String f3 = "<span class='blue'>" +"Uploaded <b>Config file</b> " +fileName+ "<br>" + "</span>";
                             request.setAttribute("f3stat", f3);

                             String content="";
                             if(new File(fpath).exists())
                                {
                                    String my = fpath + "/gecofile.geco";

                                    BufferedReader reader = new BufferedReader(new FileReader(my));
                                        String line1;
                                        while ((line1 = reader.readLine()) != null) 
                                            {
                                                content= content + line1 +"\n";
                                            }
                                }
                             request.setAttribute("File_Text", content);
                             RequestDispatcher rd = request.getRequestDispatcher("geco");
                             rd.forward(request, response); 
                         }

PS: The cookie is set when form1 is submitted to doGet() and here in doPost() I am accessing the same cookie value.

PS: I've tried changing getAttribute to getParameter still the value remains null.

Answer 1

The input field adds properly. Check request with FireBug if the data from hidden input is there, it should be. It is rather your servlet issue. Maybe because you use different names for the forms. Maybe because you give different values for input.name . Code above works fine. The reason might be also in that your first form toexecute does have no action field.

You give us to little data about server side code to solve this problem.

EDIT:

I don't have experience in Java Servlets so I'm just shooting. At first time you send GET and request.getAttribute() works. Second time you send POST, and there is issue with that. Since you send images, that is encoded data, you can't read it normally. I think you will find your answer here:

HttpServletRequest get JSON POST data

EDIT2:

Try this method. It should do the job:

request.getServletContext().getAttribute("attr_name");

EDIT3:

Because you're using Tomcat 6, you have issue with hadling multipart/form-data. Here is similiar problem and solution:

Convenient way to parse incoming multipart/form-data parameters in a Servlet

You should move to Tomcat 7.

Answer 2

Inside your servlet you need to be getting the request parameter called mytxt1 not an attribute set in the request with that name (unless there's some code you haven't shown us). Change this line:

String TEXT = request.getAttribute("mytxt1").toString();//This is where it is displaying null

to

String TEXT = request.getParameter("mytxt1");