Swift多部分文件上传报错：Required request part 'file' is not present

问题代码 #

尝试通过Multipart文件上传方式上传头像，Swift实现代码如下：

func uploadPhoto(image: UIImage, filePath: String, completion: @escaping uploadPhotoClosure) {
    
    let imageData = image.jpegData(compressionQuality: 0.3)
    
    let url = "https:www.somepath.com/uploadFile"
    var request = URLRequest(url: URL(string: url)!)

    request.httpMethod = "POST"
    let boundary = UUID().uuidString
    let contentType = "multipart/form-data; boundary=\(boundary)"
    request.addValue(contentType, forHTTPHeaderField: "Content-Type")
    request.addValue("application/json", forHTTPHeaderField: "Accept")
    
    var body = Data()
    
    body.append("\r\n--\(boundary)--\r\n".data(using: String.Encoding.utf8)!)
    body.append("Content-Disposition: form-data; name=\"file\"\r\n\r\n".data(using: String.Encoding.utf8)!)
    body.append("field_mobileinfo_image".data(using: String.Encoding.utf8, allowLossyConversion: true)!)
    
    body.append("\r\n--\(boundary)\r\n".data(using: String.Encoding.utf8)!)
    body.append("Content-Disposition: form-data; name=\"files[field_mobileinfo_image]\"; filename=\"img.jpg\"\r\n".data(using: String.Encoding.utf8)!)
    body.append("Content-Type: application/octet-stream\r\n\r\n".data(using: String.Encoding.utf8)!)
    body.append(imageData!)
    body.append("\r\n--\(boundary)\r\n".data(using: String.Encoding.utf8)!)
    
    request.httpBody = body
    self.serviceManager.async(request: request) { (innerClosure) in
        do {
            let response = try innerClosure()
            guard let json = response.jsonObject else {
                completion({ throw JSONErrorType.parsingError })
                return
            }
            let jsonData = try JSONSerialization.data(withJSONObject: json, options: [])
            let responseModel = try JSONDecoder().decode(EditProfilePhotoUploadResponse.self, from: jsonData)
            completion({ return responseModel })
        } catch {
            completion({ throw error })
        }
    }
}
//servicemanager class
func async(request: URLRequest, completion: @escaping ServiceManagerAsyncCompletion) {
    ServiceManager.log(request)
    
    let task = self.urlSession.dataTask(with: request) { (data, response, error) in
        guard error == nil else {
            DispatchQueue.main.async {
                completion({ throw error! })
            }
            return
        }
        
        guard let response = response as? HTTPURLResponse else {
            DispatchQueue.main.async {
                completion({ throw ServiceErrorType.invalidResponse })
            }
            return
        }
        
        ServiceManager.log(response, withBody: data)
        //here handling status code
        
    }
}

服务器错误响应 #

{
"status" : 500,
"message" : "Required request part 'file' is not present",
"timestamp" : "2022-08-05T05:30:55.415+0000",
"path" : "/uploadFile",
"error" : "Internal Server Error"
}

解决建议 #

• 修正Multipart边界格式：请求体开头错误使用了闭合边界--\(boundary)--，正确结构应以起始分隔符--\(boundary)开头，字段间用--\(boundary)分隔，最终用--\(boundary)--闭合。
• 匹配服务器要求的字段名：服务器提示缺少file字段，当前代码中文件字段名为files[field_mobileinfo_image]，与要求不符。需将该字段名改为name="file"，同时移除多余的file字符串字段（即那段field_mobileinfo_image文本）。
• 调整请求体拼接逻辑：正确的Multipart文件上传请求体示例：

  guard let imageData = image.jpegData(compressionQuality: 0.3) else {
      completion({ throw UploadError.failedToConvertImage })
      return
  }
  
  var body = Data()
  // 起始分隔符
  body.append("--\(boundary)\r\n".data(using: .utf8)!)
  // 文件字段
  body.append("Content-Disposition: form-data; name=\"file\"; filename=\"img.jpg\"\r\n".data(using: .utf8)!)
  body.append("Content-Type: image/jpeg\r\n\r\n".data(using: .utf8)!)
  body.append(imageData)
  body.append("\r\n".data(using: .utf8)!)
  // 闭合边界
  body.append("--\(boundary)--\r\n".data(using: .utf8)!)
  

• 修复URL格式：当前URLhttps:www.somepath.com/uploadFile缺少//，应改为https://www.somepath.com/uploadFile，避免请求地址无效。
• 处理可选值安全问题：移除imageData!的强制解包，添加空值判断，防止因图片转换失败导致崩溃。

内容的提问来源于stack exchange，提问作者Anilkumar iOS Developer