import json
import urllib
from urllib import request
from urllib import parse

def Payload(start_date, end_date, pnode_list):
    payload = {"startDate": start_date, 
               "endDate": end_date,
               "pnodelist": pnode_list}
    return json.dumps(payload)

def DownloadData(url, payload, header):
    data = []
    request = urllib.request.Request(url, payload, header)
    try:
        response = urllib.request.urlopen(request)
    except urllib.error.URLError as e:
        print("URLError occured.")
    except urllib.error.HTTPError as e:
        print("HTTPError occured.")
    else:
        #response.chunked = False
        data = json.loads(response.read().decode("utf-8"))
    return data

def main():
    url = "https://dataminer.pjm.com/dataminer/rest/public/api/markets/dayahead/lmp/daily"
    payload = Payload("2015-07-01", "2015-07-01", [135389795])
    header = {"Content-Type": "application/json"}
    data = DownloadData(url, payload.encode("utf-8"), header)
    print(data)

if __name__ == "__main__":
    main()