I want the facility to upload a file, storing it into a Blob field on the datastore.

My model looks like

class Kitten(db.Model):
  index = db.IntegerProperty(default=0)
  name = db.StringProperty(required=True)
  picture = db.BlobProperty()
  votes = db.IntegerProperty(default=0)

Then we create a form called that we can use to hold that data,

class KittenForm(djangoforms.ModelForm):
    class Meta:
      model = Kitten
      exclude = [ 'index' ]

In our add method, we attempt to load the form, and validate it if we have been posted back,

if request.method == "POST":
    # Handle form submission
    form = KittenForm(request.POST, request.FILES)
    if (form.is_valid()):
      # Do stuff
  else:
    form = KittenForm()
  return render_to_response('addkitten.html', {'form': form})

At first we just don’t get a file upload button in our form, this is because Django 0.97.1 doesn’t support FileFields properly, so AppEngine wont map a Blob to one unless you upgrade to django 1.0

Once that’s done, and we’re running AppEngine from subversion as well to get latest code fixes there. when we post to the method, we get an attribute error,

'NoneType' object has no attribute 'validate'

This appears to be caused by the clean_for_property_field calling property_clean.

When the model is created, it sets up a set of property cleaners, one for each field on the model.

The code to do so looks like:

in google/appengine/ext/db/djangoforms.py:
for name, field in model_fields.iteritems():
  prop = props.get(name)
  if prop:
    def clean_for_property_field(value, prop=prop, old_clean=field.clean):
      value = old_clean(value)
      property_clean(prop, value)
      return value
    field.clean = clean_for_property_field

According to my traceback, prop is equal to None when clean_for_property_field is called back by django.

However, it looks to me like what has happened is that the code that calls the above code has changed in how it calls it, passing in a second parameter called initial, but only when it’s a FileField.

if isinstance(field, FileField):

    initial = self.initial.get(name, field.initial)

    value = field.clean(value, initial)

else:

    value = field.clean(value)

I’m very excited about this, because I’ll also be getting to meet Mano Marks from Google who will be giving an App Engine code lab at PyConUK.

Twitter messages are still appearing on the side bar but wont come out in RSS or as posts anymore.

Feel free to follow me in twitter if you want to see my twitter messages

Even with sleep deprivation I worry about Facebook, I’ve considered a number times deleting my account as I worry about my privacy.  Facebook is not known for it’s good terms of service with regard to privacy.  Maybe the sleep deprivation is making me more paranoid, but I decided to check out the terms of use for FaceBook with regard to posting pictures, photo’s and other User Generated content.

What I found shocked me to the core, and means that I will be deleting my Facebook account permanantly and refusing to use it anymore (in about 7 days, I need to let everyone know).

The terms of service read

“When you post User Content to the Site, you authorize and direct us to make such copies thereof as we deem necessary in order to facilitate the posting and storage of the User Content on the Site. By posting User Content to any part of the Site, you automatically grant, and you represent and warrant that you have the right to grant, to the Company an irrevocable, perpetual, non-exclusive, transferable, fully paid, worldwide license (with the right to sublicense) to use, copy, publicly perform, publicly display, reformat, translate, excerpt (in whole or in part) and distribute such User Content for any purpose, commercial, advertising, or otherwise, on or in connection with the Site or the promotion thereof, to prepare derivative works of, or incorporate into other works, such User Content, and to grant and authorize sublicenses of the foregoing.”

In english what this says is, When you put anything on facebook, you allow facebook to do anything with your stuff that they want to do, including advertising with it, and selling it as part of a commercial operation, and the ability to grant that exact same license to anybody else they want.

So if I upload a photo of my baby, and facebook decides to collect together a catalog of baby photos, sell them to any company that wants them, they can do so.

Flickr on the otherhand says “With respect to photos, graphics, audio or video you submit or make available for inclusion on publicly accessible areas of the Service other than Yahoo! Groups, the license to use, distribute, reproduce, modify, adapt, publicly perform and publicly display such Content on the Service solely for the purpose for which such Content was submitted or made available. This license exists only for as long as you elect to continue to include such Content on the Service and will terminate at the time you remove or Yahoo! removes such Content from the Service.”

Which basically says that when you upload your photo’s you get to decide if those photo’s are copyrighted and cant be used, or creative commons and can be used for say non-commercial purposes, or completely public and free for all. If you change ytour mind later and delete the phot, then Yahoo! will honour that decision.

You can find my flickr photostream at http://www.flickr.com/photos/mibgames/

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