Fixing a `form-data` boundary error

I'm starting to use err tag on this blog to document these small things.

I was trying out an endpoint that takes a file field. The code looked something like this.

 1import requests
 2
 3file = {'document': open('document.pdf', 'rb')}
 4
 5headers = {
 6    'Content-Type': 'multipart/form-data',
 7    'Accept': 'application/json'
 8}
 9
10response = requests.post(url,
11    files=file,
12    headers=headers)

Upon sending this request, I was greeted with a "boundary error".

The reason why this is happening is requests will try to write the Content-Type and boundary strings in the post request. If you manually set Content-Type, the boundary strings will be missing.