MultiValueDictKeyError for django image File upload

Question

I have spent a LOT of time trying to resolve this- Read Django docs, consulted forms but not got anything satisfactory. So please be patient here with me. I am trying to do an upload of an Image file here from my html template. This is my html form

<form id="tryOnPageForm" method="POST" enctype="multipart/form-data" action="/dummy/{{frame.slug}}/">
{% csrf_token %}
  <input type="file" name="uploadFromPC" id="uploadFromPC" class="myButton" title="Upload From PC" value= "Upload from PC" onchange="uploadPC()" style="float:left;">
 <input type="submit" id="Submit" class="myButton" value= "Done" style="display:none"><br><br>

 </form>

The file upload happens properly an d I am able to see the uploaded image file in the HTML.

In my views.py,

def upload_image(request, frameslug):

frame= v.objects.get(slug=frameslug)
if request.method == 'POST':
    form = ImageUploadForm(request.POST, request.FILES)
    print "FILES", request.FILES
    if form.is_multipart():
        save_file(request.FILES['image'])
        return HttpResponseRedirect('Successful')
    else:
        return HttpResponse('Invalid image')
else:
    form = ImageUploadForm()
return render_to_response('dummy.html', {'form': form})


def save_file(file, path=''):
    ''' Little helper to save a file
    '''
    filename = file._get_name()
    fd = open('%s/%s' % (MEDIA_ROOT, str(path) + str(filename)), 'wb')
    for chunk in file.chunks():
        fd.write(chunk)
    fd.close()

and in my forms.py,

from django import forms
class ImageUploadForm(forms.Form):   
image = forms.ImageField(label='Select a file', help_text='max. 20 megabytes')

When I run my code I get this error

MultiValueDictKeyError at /dummy/fr1234/

The print statement in my from my view.py shows this

FILES <MultiValueDict: {u'uploadFromPC': [<InMemoryUploadedFile: model4.jpg (image/jpeg)>]}>

and this is the traceback

Traceback:
File "C:\Python27\lib\site-packages\django\core\handlers\base.py" in get_response
  112.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File "D:\Work-Backup\LiClipse Workspace\vTryON_DJango_Integration\vTryON\views.py" in upload_image
  189.             save_file(request.FILES['image'])
File "C:\Python27\lib\site-packages\django\utils\datastructures.py" in __getitem__
  301.             raise MultiValueDictKeyError(repr(key))

Exception Type: MultiValueDictKeyError at /dummy/fr1234/
Exception Value: "'image'"

I am aware that the enctype should be multipart/form-data since I have read it in tutorials. ALso, i have not used any field in my models.py to store the uploaded image.Instead I want to directly save it to thr MEDIA_URL location.Might that be an issue? Please help. This has held me up for a long time. Thanks in advance.

Answer 1

I was able to solve this(after spending a lot of time and with some help from my friends...)

I think the error

Exception Type: MultiValueDictKeyError at /dummy/fr1234/ Exception Value: "'image'"

was coming because request.FILES was unable to get the uploaded image from the user input, the reason being that the name of the user input file that I provided was wrong!!

It should have been request.FILES['uploadFromPC'] instead of request.FILES['image'] because that is the name that I had kept in my HTML.

<input type="file" name="uploadFromPC" id="uploadFromPC" class="myButton" title="Upload From PC" value= "Upload from PC" onchange="uploadPC()" style="float:left;">

That was a stupid error and a lot of time wasted to fix it.. :(

.. but ya, good learning.

I hope this helps somebody else who is trying to do something similar. Although, I would like it if somebody can explain to me the use of forms.py here. Is it possible to do an user upload without forms.py?

Answer 2

I found that the error occurs when you submit the form without selecting the file. when a file is not selected then the input_name in your case image is u''. this gives the error as the dictionary has no such key.
i tried to find a way to try and except error but there is no such exception in python MultiValueDictKeyError