Basic Python example of how to connect to server (JSON, Alt Naming)

This script does not use official package with Protobuf communication but rather uses JSON communication.

Things to do before running the script:

1. pip install websockets
2. put credentials.json right beside the script
3. put OAModel.custom.json and payloadTypes.custom.json right beside the script. (check below to see how to create them)

import json
import asyncio as aio
from types import SimpleNamespace
from websockets.asyncio.client import connect # pip install websockets

# utils
parsejson = lambda s: json.loads(s, object_hook=lambda d: SimpleNamespace(**d))
def readfile(path):
  with open(path) as f:
    return parsejson(f.read())

creds = readfile('./credentials.json')
oa = readfile('./OAModel.json')
pt = readfile('./payloadTypes.json')


# set up a function for constructing client messages
def construct_msg(payloadType, fields={}):
  msg = {
    'payloadType': payloadType,
    'payload': {
      'ctidTraderAccountId': creds.accountId,
      'accessToken': creds.accessToken,
      **fields
    }
  }
  return json.dumps(client_msg)


async def main():
  async with connect('wss://live.ctraderapi.com:5036') as ws:
    print('Application authentication')
    # we don't use the `construct_msg()` function for the first message,
    # because its payload is different from the rest of the messages
    client_msg = {
      'payloadType': pt.req.ApplicationAuth,
      'payload': {
        'clientId': creds.clientId,
        'clientSecret': creds.clientSecret
      }
    }
    await ws.send(json.dumps(client_msg))
    server_msg = parsejson(await ws.recv())
    if server_msg.payloadType != pt.res.ApplicationAuth:
      print('Application authentication failed')

    print('Account authentication')
    client_msg = construct_msg(pt.req.AccountAuth)
    await ws.send(client_msg)
    server_msg = parsejson(await ws.recv())
    if server_msg.payloadType != pt.res.AccountAuth:
      print('Account authentication failed')

    print('Getting symbols list')
    client_msg = construct_msg(pt.req.SymbolsList)
    await ws.send(client_msg)
    server_msg = parsejson(await ws.recv())
    if server_msg.payloadType != pt.res.SymbolsList:
      print('Getting symbols failed')

    print('Saving symbol list to file')
    symbols = [sym.__dict__ for sym in server_msg.payload.symbol]
    with open('symbols.json', 'w', encoding='utf-8') as f:
      json.dump(symbols, f, ensure_ascii=False, indent=2)

aio.run(main())

How to get the JSON definition files.

Run below snippet to create the OAModel.json file. Before running the snippet you need to have cTrader OpenAPI Python package installed: pip install ctrader_open_api

note

When using JSON communication, we don't need the ctrader_open_api package anymore. We're only installing it to extract the neccessary information into the OAModel.json file and we no longer need it afterwards so we can uninstall it with pip uninstall ctrader_open_api -y after we ran the snippet.

import ctrader_open_api.messages.OpenApiModelMessages_pb2 as OAModel
import json

# get OAModel in custom format
# we're deleting "PayloadType" since we're getting it separately
target_keys = filter(lambda i: i.startswith('ProtoOA'), dir(OAModel))
ones_with_keyval = filter(lambda k: hasattr(getattr(OAModel,k),'keys'), target_keys)
out = {}
for key in ones_with_keyval:
  prop = getattr(OAModel, key)
  name = key.split('ProtoOA')[1]
  out[name] = dict(zip(prop.keys(), prop.values()))
del out['PayloadType']
with open('OAModel.custom.json', 'w', encoding='utf-8') as f:
  json.dump(out, f, ensure_ascii=False, indent=2)


# get payloadTypes in custom format
excp = {'SLTP':'SLTP', 'PNL':'PnL'}
out = {'req': {}, 'res': {}, 'event': {}}
for key, val in OAModel.ProtoOAPayloadType.items():
  parts = key.split('PROTO_OA_')[1].split('_')
  type = parts[-1].lower()
  name = ''.join([excp[i] if i in excp else i.title() for i in parts[:-1]]) # PascalCase (proper)
  # name = ''.join(map(str.title, parts[:-1]))  # PascalCase (naive)
  # name = '_'.join(parts[:-1])                 # UPPER_SNAKE_CASE
  # name = '_'.join(map(str.lower, parts[:-1])) # snake_case
  out[type][name] = val
out['common'] = {'Message': 5, 'ErrorRes': 50, 'HeartbeatEvent': 51}
with open('payloadTypes.custom.json', 'w', encoding='utf-8') as f:
  json.dump(out, f, ensure_ascii=False, indent=2)