当我尝试设置python3脚本从api网关向lambda发送请求时，即使我在post请求的正文中有请求消息，我还是收到错误。我不确定是什么导致了这个问题。
我的 Postman 请求中的json主体是这样的：
{ "message": "what is the capital of Texas" }
有人能帮帮我吗？

import openai
import json


def lambda_handler(event, context):
    request_body = None
    if "body" in event:
        request_body = json.loads(event["body"])
    else:
        # Handle the case where the event does not have a "body" key
        return {
            "statusCode": 400,
            "body": json.dumps({ "error": "Request must contain a message in the body." })
        }
    # Get the message from the request body
    message = request_body["message"]
        # Check if the request body contains a message
    if request_body is None or "message" not in request_body:
        # Return an error message in the HTTP response
        return {
            "statusCode": 400,
            "body": json.dumps({ "error": "Request must contain a message in the body." })
        }
    # print body api gets
    print(request_body)
    # set API key env
    OPENAI_API_KEY = 'XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX'
    openai.api_key = api_key

# Use GPT-3 to generate a response
response = openai.Completion.create(
    engine="davinci",
    prompt=message,
    temperature=0.5,
    max_tokens=1024,
    top_p=1,
    frequency_penalty=1,
    presence_penalty=1,
    api_key=api_key
)

# Extract the response message from the response
response_message = response["choices"][0]["text"]

# Return the response message in the HTTP response
return {
    "statusCode": 200,
    "body": json.dumps({ "message": response_message })
}`

我已经阅读了所有的博客和信息在线使用api门的方式和错误，我得到的是以下。
回复：
{ "statusCode": 400, "body": "{\"error\": \"Request must contain a message in the body.\"}" }