[Python] How to create a LIMIT Order for MEXC using python?

I am trying to create a limit order for MEXC. I defined two functions: one is used to generate a signature and the seconde one creates the limit order.

Generate a signature:

def generate_signature(params):

# 1. Sort parameter alphabetically
sorted_params = sorted(params.items())

# 2. Change to Query-String (key1=value1&key2=value2)
query_string = urlencode(sorted_params)

# 3. Generate HMAC-SHA256 Signatur
signature = hmac.new(
self.api_secret.encode('utf-8'),
query_string.encode('utf-8'),
hashlib.sha256
).hexdigest()

return signature


Create a limit order:

def create_limit_order():
try:
params = {
"symbol": "BTCUSDT", # "BTCUSDT", String
"side": "BUY", # "BUY" oder "SELL", String
"type": "LIMIT", # String
"price":limit_price, # float
"quantity": quantity, # float
"timestamp": int(time.time() * 1000), #float
}

signature = generate_signature(params)

headers = {
"X-MEXC-APIKEY": api_key,
'Content-Type': 'application/json'
}

response = requests.post(
"https://api.mexc.com/api/v3/order",
params={**params, "signature": signature},
headers=headers,
timeout=10,
)

if response.status_code == 200:
response = response.json()
print(f"Order platziert! Order ID: {response['orderId']}")
return order_data['orderId']
else:
print(f"Error {response.status_code}: {response.text}")
return None

except Exception as e:
print(f"Order placement failed: {str(e)}")
return None




def main():
create_limit_order()

if __name__ == "__main__":
main()


In the main I am calling the function to create the limit order, but unfortunately I receive the following error:

Status-Code: 400
Antwort: {"code":700002,"msg":"Signature for this request is not valid."}


What is the problem? Can anyone help?

I tried to find the problem about the signature, but I cant find the root cause. I changed the data type for "price" and "quantity" to strings but the result remains the same.

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