Auto download not working for Django FileResponse

Question

I need to let the Django auto download the generated file.

Tried all different solutions online, none of them works.

Views.py

def validate(request):
    if request.method == 'POST':
        filename = request.POST.get('source_file')
        file_path = os.path.join(settings.MEDIA_ROOT, 'SourceFiles', filename)
        region = request.POST.get('region')
        product_type = request.POST.get('product_type')
        result = validateSource.delay(file_path, region, product_type)
        output_filepath, log_filepath = result.get()
        if os.path.exists(output_filepath) and os.path.exists(log_filepath):
            zip_filename = zipFiles([output_filepath, log_filepath], filename)
            zip_filepath = os.path.join(settings.MEDIA_ROOT, zip_filename)
            response = FileResponse(open(zip_filepath, 'rb'), as_attachment=True)
            return response
        raise Http404

Template: code for the form POST.

     $(document).on('submit', '#productForm', function(e){
       e.preventDefault();
       var inputFilePath = document.getElementById('sourceFileInput').files.item(0).name;
        $.ajax({
            method: 'POST',
            url: 'validate/',
            data: {
              source_file: inputFilePath,
              region: $("#Region-choice").val(),
              product_type: $("#Product-type").val()}
            })
            .done(function(){
                document.getElementById('lblStatus').innerHTML = "Result: <br/>"
                document.getElementById('lblStatusContent').innerHTML = "Success!"

            })
            .fail(function(req, textStatus, errorThrown) {
                document.getElementById('lblStatus').innerHTML = "Result: <br/>"
                alert("Something went wrong!:" + textStatus + '  ' + errorThrown )
            });
    });
 });

@dirkgroten well, nothing happends when the response returned. I am expecting the file to be automatically downloaded when the FileResponse returned. — flgn, May 22 '19 at 14:37
but if the `FileResponse` is returned, you would either see the file inline in your browser or it would be downloaded. What do you see in your browser Network tab? what are the headers of response? Do you see the file being returned there? And is the Content-Disposition header set for the response? — dirkgroten, May 22 '19 at 14:39
Could you be making a GET request? Is it returning a 404 because the file doesn't exist? Did you try doing a simple view that returns the FileResponse and then working backwards adding in more of your logic? — schillingt, May 22 '19 at 14:40
@dirkgroten yes, I can see the file in the response headers. And for the `Content-Dispositioin`, according to the offcial docs, **If as_attachment=True, the Content-Disposition header is set, which asks the browser to offer the file to the user as a download.**, seems I don't need to set it manually anymore. And in the response, it says **Content-Disposition: attachment; filename="Final.zip"**, looks correct. — flgn, May 22 '19 at 14:43
what makes the POST request? If is a normal html form submission or is it an xhr? — dirkgroten, May 22 '19 at 14:46
@schillingt The file does exist and it is also in the response headers. — flgn, May 22 '19 at 14:49
have you tried different browsers? I'm wondering if responding to a POST with a file to download is always treated the same way. Note that in general, you should *always* redirect on a POST so you then have a GET to fetch the success page. That's because otherwise you "break" the back button. — dirkgroten, May 22 '19 at 15:30
and have you tried with something else than a zip file? I think the browser could be a cause here. — dirkgroten, May 22 '19 at 15:31
@dirkgroten Yes, also tried in FF, still the same. For redirecting, I doubt if I should use that, because I want to stay on the same page and without refreshing the page. — flgn, May 22 '19 at 15:33
@dirkgroten Tried with a simple and small .txt file, no magic happened... — flgn, May 22 '19 at 15:38
you said is was a normal html form post, but apparently it's not: you're making an XHR request! — dirkgroten, May 22 '19 at 15:52
@dirkgroten okay, then I mixed them up... Could this be the issue then? — flgn, May 22 '19 at 15:55
yes of course, you're not doing anything with the file that's returned in your `done` handler. — dirkgroten, May 22 '19 at 15:56
Possible duplicate of [Download a file by jQuery.Ajax](https://stackoverflow.com/questions/4545311/download-a-file-by-jquery-ajax) — dirkgroten, May 22 '19 at 15:59

score 2 · Accepted Answer · answered May 22 '19 at 16:01

2

It's not possible to download files to your computer via an ajax (XHR) request. So you need to redirect the user actually (setting window.location) to a view that downloads the file. Or you can add as a result of the successful POST a button the current page so the user can download the file. In any case, you need to move the file download to a different view so a standard GET request can fetch it.

But your code to return the file in Django (using FileResponse) is correct.

There's also an explanation with an alternative way of doing it here

answered May 22 '19 at 16:01

dirkgroten

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Okay, let's say the download button appears after the successful POST, how could send the returned `FileResponse`to the button click function? Probably a stupid question, but I am new to JS... – flgn May 23 '19 at 12:14
The button is just a link to another Django view (GET) where you return the FileResponse. So you need to write a different view that returns the file. It means your POST view needs to return some kind of indentifier for the file that can then be used in the GET. – dirkgroten May 23 '19 at 12:30
So, sth like this: 1. View's 1st function accepts the POST request to create the file which will be downloaded; 2. Write the 2nd function in the view to return the FileResponse 3. Use `window.location` in the success POST to redirect to the url to the view function created in the previous step to GET the file (Not sure how, will check.) – flgn May 23 '19 at 13:44
Yes that’s one possible solution. Your 1st view must return. jsonResponse with the url for the file (so that your second view “knows” which file to send back). If you use window.location the user will see a page refresh (to a blank page) before the download starts. That’s why I thought a button would work better as the user would just stay on the current page. But it’s easy to try both to decide what’s the better user experience. – dirkgroten May 23 '19 at 13:48

score 0 · Answer 2 · answered May 22 '19 at 15:10

def validate(request):
    if request.method == 'POST':
        filename = request.POST.get('source_file')
        file_path = os.path.join(settings.MEDIA_ROOT, 'SourceFiles', filename)
        region = request.POST.get('region')
        product_type = request.POST.get('product_type')
        result = validateSource.delay(file_path, region, product_type)
        output_filepath, log_filepath = result.get()
        if os.path.exists(output_filepath) and os.path.exists(log_filepath):
            zip_filename = zipFiles([output_filepath, log_filepath], filename)
            zip_filepath = os.path.join(settings.MEDIA_ROOT, zip_filename)
            with open(zip_filepath, 'rb') as fh:
                response = HttpResponse(fh.read(), content_type="application/force-download")
                response['Content-Disposition'] = 'attachment; filename=' + os.path.basename(zip_filepath)
                return response
        raise Http404

In the network, the response already shows `Content-Disposition: inline;` — flgn, May 22 '19 at 15:20

Auto download not working for Django FileResponse

2 Answers2