Issues with Python 3.6

[suminb]

As AWS Lambda announced their support for Python 3.6 a few days ago, I was testing flask-lambda with Python 3.6.

Under the FlaskLambda.__call__ method, there is this:

    body = next(self.wsgi_app(
        make_environ(event),
        response.start_response
    ))

However, the type of body always becomes bytes, and you ways end up getting the following error message when calling it via AWS Lambda.

An error occurred during JSON serialization of response: b'(your response)' is not JSON serializable

I know the following patch (body -> body.decode('utf-8')) will get my work done for now, but it is probably not a good general solution.

    return {
        'statusCode': response.status,
        'headers': response.response_headers,
        'body': body.decode('utf-8')
    }

What would be a good resolution for this issue?

[sivel]

I believe that is an error in your application and not flask_lambda. flask_lambda doesn't concern itself with your encoding. If you return a bytestring from your view function, flask_lambda will just proxy it through.

It is your responsibility to make sure you are returning a str type in python3.

[huyphan]

@sivel: I'm late to the game, but I'm afraid this is something flask_lambda should be concerned about. Even if the view function returns an object of str type, Flask still encodes it to bytes. It's pretty easy to to confirm that with the following snippet:

from flask import Flask

def start_response(self, *args, **kargs):
    return

class FlaskFooBar(Flask):
    def __call__(self, event, context):
        body = next(self.wsgi_app(event, start_response))

        print(type(body))

        return super(FlaskFooBar, self).__call__(event, context)


app = FlaskFooBar(__name__)
@app.route('/')
def hello_world():
    return 'Hello, World'

Your console would print out <class 'str'> in Python2 and <class 'bytes'> in Python3. Would you be interested in an PR for this (and some other minor optimization for multiple Python versions compatibility)?