使用MEXC API下止损限价单遇无效内容类型错误（700013）求助

尝试使用MEXC API下达止损限价单时持续报错，错误信息如下：

HTTP error occurred: 400 Client Error: Bad Request for url: https://api.mexc.com/api/v3/order
{"code":700013,"msg":"Invalid content Type."}

使用的下单脚本：

import requests
import time
import hmac
import hashlib

# Your MEXC API key and secret
API_KEY = 'your_api_key'
API_SECRET = 'your_api_secret'

# Base URL for MEXC API
BASE_URL = 'https://api.mexc.com/api/v3'

# Function to create the signature for the request
def create_signature(query_string, secret):
    return hmac.new(secret.encode(), query_string.encode(), hashlib.sha256).hexdigest()

# Function to place a stop-limit order
def place_stop_limit_order():
    endpoint = '/order'
    timestamp = int(time.time() * 1000)
    
    # Parameters for the stop-limit order
    params = {
        'symbol': 'ETHUSDC',
        'side': 'BUY',
        'type': 'STOP_LOSS_LIMIT',   # Order type
        'quantity': '0.01',         # Quantity to buy
        'price': '4000.01',          # Limit price
        'stopPrice': '4000',         # Stop price
        'timeInForce': 'GTC',        # Time in force
        'timestamp': timestamp
    }

    query_string = '&'.join([f"{key}={value}" for key, value in sorted(params.items())])
    signature = create_signature(query_string, API_SECRET)
    
    headers = {
        'X-MEXC-APIKEY': API_KEY,
        'Content-Type': 'application/x-www-form-urlencoded'  # Correct content type
    }

    # Adding signature to the query string
    query_string += f"&signature={signature}"

    # Make the request to place the order
    response = requests.post(BASE_URL + endpoint, headers=headers, data=query_string)
    try:
        response.raise_for_status()  # Raise an HTTPError for bad responses (4xx and 5xx)
    except requests.exceptions.HTTPError as err:
        print(f"HTTP error occurred: {err}")  # Print HTTP error
        print(response.text)  # Print the response content
    except Exception as err:
        print(f"Other error occurred: {err}")  # Print other errors

    return response.json()

# Main function to place the stop-limit order
def main():
    result = place_stop_limit_order()
    print(f"Order placed: {result}")

if __name__ == "__main__":
    main()

已按文档要求设置Content-Type为application/x-www-form-urlencoded，但仍收到无效内容类型错误，需排查问题并给出修正建议。

核心问题分析 #

脚本存在两个关键问题：

• 请求参数传递方式错误：MEXC POST接口要求参数以字典形式传入data参数，而非拼接成字符串直接传入。直接传字符串时，requests库可能自动修改Content-Type，导致服务器识别错误。
• 手动拼接字符串易引发编码问题：手动拼接查询字符串可能出现参数编码不规范的情况，进一步加剧内容类型识别错误。

修正后的脚本 #

import requests
import time
import hmac
import hashlib

# Your MEXC API key and secret
API_KEY = 'your_api_key'
API_SECRET = 'your_api_secret'

# Base URL for MEXC API
BASE_URL = 'https://api.mexc.com/api/v3'

# Function to create the signature for the request
def create_signature(params, secret):
    # 按key排序参数并拼接成查询字符串
    query_string = '&'.join([f"{key}={value}" for key, value in sorted(params.items())])
    return hmac.new(secret.encode(), query_string.encode(), hashlib.sha256).hexdigest()

# Function to place a stop-limit order
def place_stop_limit_order():
    endpoint = '/order'
    timestamp = int(time.time() * 1000)
    
    # Parameters for the stop-limit order
    params = {
        'symbol': 'ETHUSDC',
        'side': 'BUY',
        'type': 'STOP_LOSS_LIMIT',
        'quantity': '0.01',
        'price': '4000.01',
        'stopPrice': '4000',
        'timeInForce': 'GTC',
        'timestamp': timestamp
    }

    # 生成签名并加入参数列表
    signature = create_signature(params, API_SECRET)
    params['signature'] = signature
    
    headers = {
        'X-MEXC-APIKEY': API_KEY,
        'Content-Type': 'application/x-www-form-urlencoded'
    }

    # 直接传入参数字典，requests自动处理为正确的表单格式
    response = requests.post(BASE_URL + endpoint, headers=headers, data=params)
    try:
        response.raise_for_status()
    except requests.exceptions.HTTPError as err:
        print(f"HTTP error occurred: {err}")
        print(response.text)
    except Exception as err:
        print(f"Other error occurred: {err}")

    return response.json()

# Main function to place the stop-limit order
def main():
    result = place_stop_limit_order()
    print(f"Order placed: {result}")

if __name__ == "__main__":
    main()

关键修改说明 #

• 参数传递方式调整：将拼接好的查询字符串改为字典传入data参数，requests会自动将字典编码为符合application/x-www-form-urlencoded格式的内容，确保服务器正确识别。
• 签名生成逻辑优化：直接接收参数字典生成签名，避免手动拼接字符串可能出现的编码错误，代码更简洁可靠。
• 参数完整性保障：所有参数（包括签名）以字典形式统一传递，避免遗漏或格式偏差。

内容的提问来源于stack exchange，提问作者user313215