binary_string_bug.py

# Got hit by this crazy bug in python

result = urlfetch.fetch('http://domain/image.jpg')
multipart_upload_body = "multi part %s upload string" % result.content

# This caused an invalid ascii error since result.content is binary and python wanted to convert it to ascii. 
# The solution was not obvious, the only way we found to do it was to create a byte array then write to it like a buffer

buffer = array.array("B") # B = unsigned bytes
buffer.fromstring("multi part ")
buffer.fromstring(result.content)
buffer.fromstring(" upload string")
multipart_upload_body = buffer.tostring()

# works! string handling in python 2.x is a little odd