check_MyDemoPOSTMethod.py

import json
import urllib.request

request_data = {'name': 'User'}
request_url = 'https://my-api-id.execute-api.region-id.amazonaws.com/test/mydemoresource'
req = urllib.request.Request(request_url)
req.add_header('Content-Type', 'application/json; charset=utf-8')
jsondata = json.dumps(request_data)
jsondataasbytes = jsondata.encode('utf-8')
req.add_header('Content-Length', len(jsondataasbytes))
response = urllib.request.urlopen(req, jsondataasbytes)
print(response.read())