Why does python keep reverting to application/x-www-form-urlencoded

[DarkByte]

I am trying to send a json encoded post url so I have simplified my code for easy viewing..

    def post_json(self, url, data, referer = '', readable = True):
        if referer == '':
            referer = self.lastpage
        self.opener.addheaders = [('Content-Type', 'application/json')]


        encodeddata = json.dumps(data)

        
        res = self.opener.open(url, (encodeddata ))


        
        self.lastpage = res.geturl()
        if readable:
            return self.readable(res)
        else:
            return res 

However when I make the request , I just get this:




Anyone know why this is? I have been awake for 30 hours so im hoping its something simple lol.

Here is the full request without everything stripped out: