Swift使用Alamofire向MathPix API上传本地图片遇内部错误求助

环境：Swift 5 / Alamofire 5 / Xcode / iOS

我尝试将拍摄的照片上传至MathPix API，但一直返回Internal error。仅使用网络图片链接时请求正常，Mac终端用curl上传本地图片也没问题，确定是请求语法问题。

官方示例代码 #

cURL示例 #

curl -X POST https://api.mathpix.com/v3/text \
-H 'app_id: APP_ID' \
-H 'app_key: APP_KEY' \
--form 'file=@"cases_hw.jpg"' \
--form 'options_json="{\"math_inline_delimiters\": [\"$\", \"$\"], \"rm_spaces\": true}"'

Python示例 #

#!/usr/bin/env python
import requests
import json

r = requests.post("https://api.mathpix.com/v3/text",
    files={"file": open("cases_hw.jpg","rb")},
    data={
      "options_json": json.dumps({
        "math_inline_delimiters": ["$", "$"],
        "rm_spaces": True
      })
    },
    headers={
        "app_id": "APP_ID",
        "app_key": "APP_KEY"
    }
)
print(json.dumps(r.json(), indent=4, sort_keys=True))

我的Swift代码 #

变量定义 #

@State private var selectedImage: UIImage? // 拍摄的照片存储在此处
@State private var imagePath = "" // 图片完整路径

请求函数 #

let image = selectedImage
let imageData = image!.jpegData(compressionQuality: 1.0)!
let imageKey = "takenPhoto"
let urlString = "https://api.mathpix.com/v3/text"
let headers: HTTPHeaders = [
        "app_id": "my_working_app_id_here",
        "app_key": "my_working_app_key_here"
    ]

AF.upload(multipartFormData: { multiPart in
    multiPart.append(imageData, withName: imageKey, fileName: "takenPhoto.jpg", mimeType: "image/jpg")
}, to: urlString, headers: headers).responseJSON { response in
    switch response.result {
    case .success(_):
        if let dictionary = response.value as? [String:Any] {
            print("success", dictionary)
        } else {
            print("error")
        }
    case .failure(let error):
        print("error", error.localizedDescription)
    }
}

返回错误信息 #

["error": Internal error, "error_info": {
    id = "sys_exception";
    message = "Internal error";
}]

其他尝试 #

使用CurlDSL构造请求，仍返回相同错误：

try CURL("curl -X POST https://api.mathpix.com/v3/text -H \'app_id: my_app_id_here\' -H \'app_key: my_app_key_here\' -F image@=\(homeDirectoryString)")

解决方案 #

问题出在两个核心点：

1. 表单字段名不匹配：MathPix API要求图片字段名为file，你用的是takenPhoto，导致API无法识别图片参数。
2. 缺少必填的options_json参数：官方示例中均包含该参数，你的请求未添加，这是触发内部错误的关键原因。

修正后的请求代码：

let image = selectedImage
guard let imageData = image?.jpegData(compressionQuality: 1.0) else { return }
let urlString = "https://api.mathpix.com/v3/text"
let headers: HTTPHeaders = [
        "app_id": "my_working_app_id_here",
        "app_key": "my_working_app_key_here"
    ]

// 构造options参数
let options = [
    "math_inline_delimiters": ["$", "$"],
    "rm_spaces": true
]
guard let optionsData = try? JSONSerialization.data(withJSONObject: options) else { return }
let optionsString = String(data: optionsData, encoding: .utf8)!

AF.upload(multipartFormData: { multiPart in
    // 图片字段名改为`file`，和官方示例一致
    multiPart.append(imageData, withName: "file", fileName: "takenPhoto.jpg", mimeType: "image/jpeg")
    // 添加options_json参数
    multiPart.append(optionsString.data(using: .utf8)!, withName: "options_json")
}, to: urlString, headers: headers).responseJSON { response in
    switch response.result {
    case .success(let value):
        if let dictionary = value as? [String:Any] {
            print("success", dictionary)
        }
    case .failure(let error):
        print("error", error.localizedDescription)
    }
}

额外注意事项 #

• 用guard判断jpegData是否为空，避免强制解包导致崩溃。
• MIME类型使用标准的image/jpeg而非image/jpg。
• 若仍有问题，可开启Alamofire日志功能，对比实际发送的请求与终端curl的请求头、表单数据差异。

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