Question

I am saving a user’s image as a BlobProperty by doing:

user.image = urlfetch.fetch(image_url).content

Then I’m rendering that image using a url such as:

/image/user_id

The image must be saving because because when I do len(user.image) I get a number in the thousands. And on the local instance the image renders ok. On the deployed app, I get the following error, and when I go to the image url nothing shows in the browser:

Traceback (most recent call last):
File "/base/python27_runtime/python27_dist/lib/python2.7/wsgiref/handlers.py", line 86, in run
self.finish_response()
File "/base/python27_runtime/python27_dist/lib/python2.7/wsgiref/handlers.py", line 127, in finish_response
self.write(data)
File "/base/python27_runtime/python27_dist/lib/python2.7/wsgiref/handlers.py", line 202, in write
assert type(data) is StringType,"write() argument must be string"
AssertionError: write() argument must be string

Also, here’s the handler that serves the image:

class ImageHandler(webapp2.RequestHandler):
""" Returns image based on id. """
def get(self, *args, **kwargs):
    user = db.get(
        db.Key.from_path('User', models.User.get_key_name(kwargs.get('id'))))
    if user.image:
        self.response.headers['Content-Type'] = "image/jpeg"
        self.response.out.write(user.image)
    else:
        self.response.out.write("No image")

Just to clarify I tried both setting content-type to jpeg and png. And things are working ok on the local server. Any help would be appreciated. Thanks!

Answer 1

Answering my question, that fixes everything:

self.response.out.write(str(user.image))

It’s confusing because the example in the docs does not cast the BlobProperty as string.