如何在 firebase 云函数上解析 multipart/form-data？

Question

根据此处的文档，我一直在尝试 post 将带有文本和图像文件的 multipart/form-data object 添加到我的一个云函数中：

https://cloud.google.com/functions/docs/writing/http#multipart_data_and_file_uploads

除了我将其包装在 CORS 响应中外，我的云函数几乎与示例完全相同。看起来，无论如何，busboy 的 'field' 和 'file' 事件永远不会触发，当我打印请求 body 的 toString 方法时，我在它之前得到了一些数据变得胡言乱语。

是否可能是我在发送 FormData 时设置不正确？

这是包含我的 XMLHttpRequest() 的代码：

var formData = new FormData(document.getElementById("ticketForm"));
return new Promise(function (resolve, reject) {
      var xmlhttp = new XMLHttpRequest();
      xmlhttp.open("POST", "https://us-central1-XXXXXXX.cloudfunctions.net/ticketFunction");
      var boundary = Math.random().toString().substr(8) + "--";
      xmlhttp.setRequestHeader('Content-Type', 'multipart/form-data;charset=utf-8; boundary=' + boundary);
      // xmlhttp.setRequestHeader('Content-Type', undefined);

      xmlhttp.onload = function () {
        if (this.status >= 200 && this.status < 300) {
          resolve(xmlhttp.response);
        } else {
          reject({
            status: this.status,
            statusText: xmlhttp.statusText
          });
        }
      };
      xmlhttp.onerror = function () {
        reject({
          status: this.status,
          statusText: xmlhttp.statusText
        });
      };
      xmlhttp.send(formData);
    });

这是我的云函数：

exports.newTicketWithPhoto = functions.https.onRequest((req, res) => { cors（要求，资源，（）=> {

if (req.method === 'POST') {

  const busboy = new Busboy({ headers: req.headers });
  const tmpdir = os.tmpdir();
  console.log("Length: " + req.headers['content-length']);
  console.log(req.body.toString());

  // This object will accumulate all the fields, keyed by their name
  const fields = {};

  // This object will accumulate all the uploaded files, keyed by their name.
  const uploads = {};

  // This code will process each non-file field in the form.
  busboy.on('field', (fieldname, val) => {
    // TODO(developer): Process submitted field values here
    console.log(`Processed field ${fieldname}: ${val}.`);
    fields[fieldname] = val;
  });

  busboy.on('error', function(err){
    console.log("Error: " + err);
  });

  // This code will process each file uploaded.
  busboy.on('file', (fieldname, file, filename) => {
    // Note: os.tmpdir() points to an in-memory file system on GCF
    // Thus, any files in it must fit in the instance's memory.
    console.log(`Processed file ${filename}`);
    const filepath = path.join(tmpdir, filename);
    uploads[fieldname] = filepath;
    file.pipe(fs.createWriteStream(filepath));
  });

  // This event will be triggered after all uploaded files are saved.
  busboy.on('finish', () => {
    // TODO(developer): Process uploaded files here
    console.log(fields);
    console.log("Uploads: " + JSON.stringify(uploads));
    for (const name in uploads) {
      console.log(name);
      const file = uploads[name];
      fs.unlinkSync(file);
    }
    res.send();
  });

  req.pipe(busboy);
} else {
  // Return a "method not allowed" error
  res.status(405).send("Something weird happened");
}

}) });

我注意到的几件事是：打印 header 的 content-length 值似乎总是 return 未定义。

当我打印 req.body.toString() 方法时，我得到这个：

 ------WebKitFormBoundaryeYZHuHsOLlohyekc
Content-Disposition: form-data; name="description"

testing description
------WebKitFormBoundaryeYZHuHsOLlohyekc
Content-Disposition: form-data; name="priority"

Low
------WebKitFormBoundaryeYZHuHsOLlohyekc
Content-Disposition: form-data; name="dueDate"

2018-07-27
------WebKitFormBoundaryeYZHuHsOLlohyekc
Content-Disposition: form-data; name="customer"

zavtra
------WebKitFormBoundaryeYZHuHsOLlohyekc
Content-Disposition: form-data; name="email"

test@test.com
------WebKitFormBoundarysseArmLvKhJY0TAm
Content-Disposition: form-data; name="photo"; filename="brighthabits1.png"
Content-Type: image/png

�PNG

IHRGB���@IDATx�}�ݴտ��I�$�V���*�EH ! �:(_7m)-ݻ�ί���{-dCaf��*�=!����N����ͽ�ږm�y�׶tt�OG�ʶ,6L���L*�ć[����V;�x�+[�c�/�0;@a�5��;��]]<x��\R�cqoG`rGƵ�t����O�y�J���"
����*�,�F,��.�ib�
                 ��I�.�SV�;��h�!v��~T�EY����(u\�4+&��I��9@~wP�`N��H�;�G"7.BI��h
                                                                               P��$R
                                                                                    �0pt,�[=��E��8����$^$��
"�,�,�4�>�Y�YY|�v3JSW��
                       )�q,���i>w��A��q\-
                                         �u���ՠ�hJW�oF������W7X��]��
                                                                    )#mx������&�њ�����iu���;D��ŗL��ޥh[F�8���D�^������IW��#��

                                �
                                 �
�TL�n���� {�l�`h����r   ��S>�[���&���_�%R8���W��mok�E����R���.]#@5������j���o���e����?Ӟ�u�Ţ�Y��5�N'�Nf��Թ#ߏ��E;�<�?^X��x�uπʭ�V??�� s�plzBǶ

我不确定是什么导致了最后所有的乱码，但只有在我上传图片时才会出现这种情况。当表单数据中没有图像时，busboy 的 'field' 事件仍然没有触发，这让我相信某些东西仍然没有被正确解析。

令人沮丧，因为我似乎完全正确地遵循了文档。

Answer 1

// Node.js doesn't have a built-in multipart/form-data parsing library.
// Instead, we can use the 'busboy' library from NPM to parse these requests.
const Busboy = require("busboy")
const busboy = new Busboy({ headers: request.headers })
let fields = []
busboy.on("field", (field, val) => {
    console.log(`Processed field ${field}: ${val}.`)
    fields[field] = val
})
busboy.end(request.rawBody)

Answer 2

我正在关注这个存储库 Image Upload with Busboy 并且在 Firebase Cloud 上工作得很好。

Answer 3

官方 google 文档建议使用 Busboy npm 包，正如接受的答案所建议的那样。将这些张贴在这里以防它们对其他人有用：

https://cloud.google.com/functions/docs/writing/http#multipart_data

Answer 4

首先安装一个busboy依赖

npm i busboy

从 FormData

创建函数到 return 数据后

const getFieldsFromFormData = (headers: any, body: any) =>
new Promise(async (resolve, reject) => {
    const Busboy = require('busboy');
    const busboy = new Busboy({ headers });
    let fields: any = {};
    
    busboy.on("field", (field: string, val: any) => fields[field] = val)
    busboy.on('finish',() => resolve(fields));
    busboy.end(body)
});

在控制器中

expressInstance.post('/upload', async (req, res, next) => {

    const body = await getFieldsFromFormData(req.headers, req.body)
    console.log('MyFormData:>> ', body);

    res.send({});
})

如何在 firebase 云函数上解析 multipart/form-data？

How to parse multipart/form-data on firebase cloud functions?

multipartform-data

xmlhttprequest

firebase

busboy

google-cloud-functions