Question

Situation: An html form (with the method=”POST” and enctype=”multipart/form-data” attributes set properly) is submitted to the server, which is Django on Google’s AppEngine. It contains a file input, which is moved (not cloned) into said form and submitted through an iframe. For small files (~1mb or less) the submitted files are being found in the request.FILES dictionary, and stored in a blob. For files above 1mb, however, the look into request.FILES is returning an error, claiming the key (which is the name of the file input element) is not found in the given dict, and in fact that the request.FILES (and request.POST) dicts are empty.

Question: Is this due to a AppEngine limitation (if so, is there a workaround?) Is this related to Django in some way (do note that the enctype and method are set appropriately)? Is there some other element that is missing?

Additional Information: Please also note that I am a javascript programmer filling in for an absent Python programmer, and know only the basics. Please tailor your answers accordingly.

Relevant Python:

def media_image_upload(request):
   if request.method == 'POST':
      img = request.FILES['img']

Relevant html:

<form id="hiddenUpForm" style="display:none;" action="http://localhost:8080/media/imageUpload" enctype="multipart/form-data" target="upTarget" method="POST">
  <input name="img" id="img" type="file" accept="image/*">
  <iframe id="upTarget" name="upTarget" src="" style="width:0;height:0;border:0px solid #fff;"></iframe>
</form>

Answer 1

I believe that in order to upload files that are larger than 1 MB, you need to use the Blobstore API to create a special URL that is used for the upload; it can’t be your regular <1 MB URL.

The controller code that generates the HTML page that contains the upload form would use upload_url = blobstore.create_upload_url('media/imageUploadBig') and would then add upload_url to your template values and render the template.

The template, in turn, would contain a FORM definition something like this:

<form id="hiddenUpForm" style="display:none;" action="{{ upload_url|safe }}" enctype="multipart/form-data" target="upTarget" method="POST">

This means that you either need to have two different forms — one for files that are less than 1 MB and one for files that are larger — or you can store all of your images in the Blobstore.

See the Blobstore docs for more information.