Content-Type lookup is case sensitive

[chrisgilmerproj]

Using fetch() method from javascript and it does a lowercase operation before it send out my header. That means Content-Type becomes content-type.

This problem was noted in the code already:

https://github.com/awslabs/chalice/blob/master/chalice/app.py#L72-L75

Turns out this problem happened recently with the addition of 1a2ae87.

I suggest just checking for both:

if self.headers.get('Content-Type') == 'application/json' or \
        self.headers.get('content-type') == 'application/json' :
    self.json_body = body

Headers should be case-insensitive, so perhaps the class should lowercase all the headers as it reads them?

[jamesls]

Closing, #130 has been merged.

[chrisgilmerproj]

Thanks so much for the work on this!