Does anyone know where I can find complete sample code for uploading a local file and getting contents with MediaFileUpload?
I really need to see both the HTML form
You won't need to post JSON yourself, the client library handles that for you.
We provide full code samples already which can be found here: https://github.com/gsuitedevs/python-samples
Also you could check the file.insert reference documentation which contains a Python sample: https://developers.google.com/drive/v2/reference/files/insert
If this does not answer what you want perhaps you could explain in more details what you want to achieve and your architecture currently in place.