问题背景 #

尝试将Google Drive中的图片上传至多模态LLM进行分析，使用维基百科公开图片URL时LLM可正常返回结果，但使用Google Drive共享链接时返回错误，无法读取图片。

现有代码 #

function openRouterApiRequest() {
  var apiKey = "****";

  // var imageUrl = 'https://upload.wikimedia.org/wikipedia/commons/thumb/d/dd/Gfp-wisconsin-madison-the-nature-boardwalk.jpg/2560px-Gfp-wisconsin-madison-the-nature-boardwalk.jpg';
  var imageUrl = "https://drive.google.com/file/d/11178UwHmPb2TAnYCyxFOKXlPh-vSPecv/view?usp=sharing";

  var apiEndpoint = 'https://openrouter.ai/api/v1/chat/completions';
  
  var payload = {
    "model": "meta-llama/llama-4-maverick",
    "messages": [
      {
        "role": "user",
        "content": [
          {
            "type": "text",
            "text": "What is in this image?"
          },
          {
            "type": "image_url",
            "image_url": {
              "url": imageUrl
            }
          }
        ]
      }
    ]
  };
  
  var options = {
    'method': 'post',
    'headers': {
      'Authorization': 'Bearer ' + apiKey,
      'Content-Type': 'application/json'
    },
    'payload': JSON.stringify(payload),
    'muteHttpExceptions': true // To get the response even if the request fails
  };
  
  var response = UrlFetchApp.fetch(apiEndpoint, options);
  var responseCode = response.getResponseCode();
  var responseBody = response.getContentText();
  
  // Handle the response as needed
  Logger.log('Response Code: ' + responseCode);
  Logger.log('Response Body: ' + responseBody);
  
  // You might want to parse the responseBody if it's JSON
  try {
    var jsonResponse = JSON.parse(responseBody);
    Logger.log(jsonResponse);
  } catch (e) {
    Logger.log('Failed to parse response as JSON: ' + e.message);
  }
}

正常测试结果（维基图片URL） #

取消注释使用维基图片URL时，LLM返回正常分析结果：

{model=meta-llama/llama-4-maverick, created=1.744144885E9, system_fingerprint=, choices=[{finish_reason=stop, native_finish_reason=stop, index=0.0, logprobs=null, message={content=The image depicts a serene landscape featuring a wooden boardwalk or path that traverses through a lush grassy field. The boardwalk, constructed from weathered wooden planks, is flanked by tall grasses on both sides and appears to be slightly elevated above the surrounding terrain.

错误情况（Google Drive链接） #

使用Google Drive共享链接时，返回错误：

{"error":{"message":"Provider returned error","code":502,"metadata":{"raw":"error, status code: 500, status: , message: invalid character 'I' looking for beginning of value, body: ","provider_name":"Novita"}},"user_id":"user_2i6MRzMhAMlWPTYRLTP5uRwhSyx"}

可行解决方法 #

• 转换为Google Drive直接下载链接
  Google Drive的共享查看链接是网页地址，而非直接的图片资源URL，需修改为直接下载格式：
  原链接格式：https://drive.google.com/file/d/[FILE_ID]/view?usp=sharing
  修改后格式：https://drive.google.com/uc?export=download&id=[FILE_ID]
  针对本次的链接，修改后为：https://drive.google.com/uc?export=download&id=11178UwHmPb2TAnYCyxFOKXlPh-vSPecv
  将此链接替换代码中的imageUrl即可。

• 确认文件权限设置
  确保Google Drive中的图片已设置为「任何有链接的人都能查看」，否则LLM服务无法访问该资源。

• 使用Base64编码传入图片（替代方案）
  如果直接链接仍有问题，可通过Google Apps Script读取图片并转换为Base64编码后传入LLM：

  function getDriveImageBase64(fileId) {
    var file = DriveApp.getFileById(fileId);
    var blob = file.getBlob();
    return 'data:' + blob.getContentType() + ';base64,' + Utilities.base64Encode(blob.getBytes());
  }
  
  // 在原函数中调用并替换payload内容：
  var imageBase64 = getDriveImageBase64('11178UwHmPb2TAnYCyxFOKXlPh-vSPecv');
  // 修改payload里的image_url部分：
  {
    "type": "image_url",
    "image_url": {
      "url": imageBase64
    }
  }
  

  注意：此方法适用于较小的图片，避免Base64编码后数据过大导致请求失败。

内容的提问来源于stack exchange，提问作者user1592380