Downloading a file based on user input fields

[kenclark]

I am trying to get a page working that has some user provided input fields, and a button (or link) which will build an XML file for the user based on the inputs and send back the XML file.

I implemented the XML generation as:

FacesContext context = FacesContext.getCurrentInstance();
HttpServletResponse response = (HttpServletResponse) context.
    getExternalContext().getResponse();
response.setHeader("Content-Type", "application/xml");
response.setContentLength(xml.length());

ServletOutputStream out;
try
{
    out = response.getOutputStream();
    out.println(xml);
    out.flush();
    out.close();
    return null;
}
catch (Exception e)
{
    return handleException(e);
}
finally
{
    context.responseComplete();
}

This works fine when I use s:link to execute the action class method, but when I do it this way, the fields in the form do not get injected.

When I use h:commandButton, the fields are injected as expected, but now the redirection of the output does not work (no file is downloaded.)

Is there any happy medium wherein I can get both functionalities as I need them?

Thanks
ken

[amitev]

This works fine when I use s:link to execute the action class method, but when I do it this way, the fields in the form do not get injected.

This is because s:link does not submit the form.

When I use h:commandButton, the fields are injected as expected, but now the redirection of the output does not work (no file is downloaded.)

Try the following code:

public String download() {
    HttpServletResponse response = (HttpServletResponse)extCtx.getResponse();
    response.setContentType("application/octet-stream");
    response.addHeader("Content-Disposition","attachment;filename=" + FILE_NAME);
    PrintWriter writer = response.getWriter();

    /* DO YOUR THING (like writer.write) */

    writer.flush();
    facesContext.responseComplete();
    writer.close();

    return "result;
}

And finally - for better code design used dependency injection for the faces context.

@In FacesContext facesContext;

[kenclark]

I won't be able to try this out until later today, but let me see if I understand the changes you suggest:

1) Change from using OutputStream to using PrintWriter (it does not seem like this should change anything to me.)

2) Change from return null to return result -- is there a corresponding navigation change that needs to be done for this?  Seems like it would not matter anyway since we are doing ctx.responseComplete().

3) Slight change on when responseComplete is called -- this may change the way error processing proceeds it seems but would it affect my main problem?

Sorry if I am being dense -- is there a difference other than these that I am missing?

Thanks,
ken

[kenclark]

I tried this code...

I got an error that getWriter() had already been called, so that did not work.

I made the response.setHeader and addHeader changes but that had no effect.

It just seems that on a post, the strategy of re-routing the response cannot work.  Is there any way to do this?

Alternately, is there a way I could set up the pages.xml configuration in such a way that I can do this?

Thanks,
ken