Method 1:

def get_positions(susertoken, actid):
url = base_url + "PositionBook"
data = {
    "uid": "TEST18",
    "actid": actid
}
payload = {
    "jData": json.dumps(data),
    "jKey": susertoken
}

headers = {
    'Content-Type': 'application/x-www-form-urlencoded'
}
response = requests.post(url, headers=headers, data=payload)
response_text = response.text
print(response_text)

Method 2:

def get_positions(susertoken, actid):
url = base_url+"PositionBook"
data = {
"jData": '{"uid":"TEST18", "actid":"' + actid + '"}',
"jKey": susertoken
}

payload = "jData="+json.dumps(data)

headers = {
    'Content-Type': 'application/json'
}
response = requests.request("POST", url, headers=headers, data=payload)
response_json = response.json()
print(response_json)

API I am using is here – https://shoonya.com/api-documentation#positions-book
login is successful and susertoken and actid are correct