Question

I’m using the Python implementation of the Google App Engine. When I try to pass an array of image input tags from an html form, I can’t seem to pick it up in the Python controller.

The Html:

<form action="/addImages" method="post" enctype="multipart/form-data">
  <input type="file" name="images" />
  <input type="file" name="images" />
  <input type="file" name="images" />
</form>

The Python:

class AddImages(webapp.RequestHandler):
def post(self):
    images = self.request.get_all('images')

    for img in images:
        if img != None:
            img_entity.blob = db.Blob(img)

    self.response.out.write("Upload Succeeded")

When I try this, I get the dreaded unicode/str error:

TypeError: Blob() argument should be str instance, not unicode

at the line where:

db.Blob(img)

I followed most of the tutorials, but none of them seemed to discuss this particular issue.

Answer 1

You need to include the

enctype="multipart/form-data"

attribute on your form tag, see i.e. http://www.mail-archive.com/[e-mail]/msg03314.html. Googling for your error turns up several other instances of the problem.

If you still have problems once you’ve added the enctype, just try db.Blob(str(img)) and / or db.Blob(img.encode('utf-8')) as also suggested by threads like the above. You can also try images =self.request.str_GET['images'] or something similar.