ESP32调用OpenAI Chat Completions API遇HTTP 400错误求排查

HTTP 400错误表示请求格式或参数不符合API要求，结合你的代码，主要问题和修复方案如下：

核心问题：API端点错误 #

gpt-3.5-turbo属于聊天模型，必须使用聊天接口端点，你当前使用的是旧的补全接口端点，这是导致400错误的主要原因。

修复步骤 #

1. 修正API端点
   将原代码中的：

   http.begin("https://api.openai.com/v1/engines/gpt-3.5-turbo/completions");
   

   修改为：

   http.begin("https://api.openai.com/v1/chat/completions");
   

2. 验证Authorization头构造
   确保Authorization头的格式正确，Bearer后必须有一个空格，可调整为更稳妥的拼接方式：

   String authHeader = "Bearer ";
   authHeader += apiKey;
   http.addHeader("Authorization", authHeader);
   

3. 增加调试步骤
   在发送请求前打印序列化后的payload，确认格式是否符合要求：

   Serial.println("Payload:");
   Serial.println(payloadStr);
   

   同时在错误分支中打印API返回的错误详情，OpenAI通常会给出具体错误原因：

   String errorResponse = http.getString();
   Serial.println("Error Details: " + errorResponse);
   

修复后的完整代码示例 #

#include <ArduinoJson.h>
#include <WiFi.h>
#include <HTTPClient.h>

const char* ssid = "ssid";
const char* password = "password";
const char* apiKey = "api";

const char* userMessage = "Hey there ! how are you ?";

void setup() {
  Serial.begin(115200);
  delay(1000);

  // Connect to Wi-Fi
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi...");
  }
  Serial.println("Connected to WiFi");

  // Prepare the JSON payload
  DynamicJsonDocument payload(1024);
  payload["model"] = "gpt-3.5-turbo";
  
  JsonArray messages = payload.createNestedArray("messages");
  
  JsonObject systemMessage = messages.createNestedObject();
  systemMessage["role"] = "system";
  systemMessage["content"] = "You are a helpful assistant.";
  
  JsonObject userMessageObject = messages.createNestedObject();
  userMessageObject["role"] = "user";
  userMessageObject["content"] = userMessage;

  // Serialize the JSON payload
  String payloadStr;
  serializeJson(payload, payloadStr);
  
  // 调试：打印payload
  Serial.println("Payload:");
  Serial.println(payloadStr);

  // Send the request to the OpenAI API
  HTTPClient http;
  // 修正后的API端点
  http.begin("https://api.openai.com/v1/chat/completions");
  http.addHeader("Content-Type", "application/json");
  
  // 构造Authorization头
  String authHeader = "Bearer ";
  authHeader += apiKey;
  http.addHeader("Authorization", authHeader);
  
  int httpResponseCode = http.POST(payloadStr);
  
  if (httpResponseCode == 200) {
    String response = http.getString();
    Serial.println("API Response:");
    Serial.println(response);
  } else {
    Serial.println("HTTP Error: " + String(httpResponseCode));
    // 调试：打印错误详情
    String errorResponse = http.getString();
    Serial.println("Error Details: " + errorResponse);
  }

  http.end();
}

void loop() {
}

内容的提问来源于stack exchange，提问作者user3793520