Firebase Cloud Storage - 使用元数据上传 -

我希望从浏览器上传带有元数据的文件，以便通过云功能正确识别和处理文件。

在客户端上，我的上传器代码如下所示：

    uploadTaskPromise: async function (file) {
      return new Promise((resolve, reject) => {      
        const storageRef = storage.ref();
        const myRef = storageRef.child(`myfolder/${my_file_name}.wav`);
        const metadata = {
          project_id: my_project_id
        };
       
        const uploadTask = myRef.put(file, { metadata: metadata });    
        uploadTask.on("state_changed",(snapshot) => {
          const progress = (snapshot.bytesTransferred / snapshot.totalBytes) * 100;
          console.log("Upload is " + progress + "% done");            
         },   
         function error(err) {
           console.log("error", err);
           reject();
          }, 
          function complete() {
          uploadTask.snapshot.ref.getDownloadURL()
          .then(function (downloadURL) {
             resolve(downloadURL);
           });
         }    
       )
     });
   },

在服务器上（使用 Node js 的 Firebase Cloud Functions）

exports.uploadHandler = functions.storage.object().onFinalize(async (object) => { 
  const bucket = admin.storage().bucket(object.bucket);
  const metadata = await bucket.file(object.name).getMetadata()
  console.log("METADATA: " + JSON.stringify(metadata))
 
  // THIS IS WHERE I WANT TO HANDLE UPLOADS BASED ON THE METADATA
  
  return ({ message: "file uploaded" })
});

The uploadHandler正在工作 - 但是metadata is undefined, as is metadata.metadata

如何访问从客户端上传的元数据？

你们真的很亲密。根据API参考 https://firebase.google.com/docs/reference/js/v8/firebase.storage.Reference#put，第二个参数是UploadMetadata object https://firebase.google.com/docs/reference/js/v8/firebase.storage.UploadMetadata它有一个名为customMetadata https://firebase.google.com/docs/reference/js/v8/firebase.storage.UploadMetadata#optional-custommetadata.

因此，要更正您的代码，您需要换出

myRef.put(file, { metadata: metadata });

with

wmyRef.put(file, { customMetadata: metadata });

此外，您的进度逻辑不应调用resolve and reject就像现在一样——那就是反模式 https://stackoverflow.com/questions/23803743。你应该改为链接到UploadTask自己的 Promise API。

return wmyRef.put(file, { customMetadata: metadata })
  .then(
    (snapshot) => { // onComplete
      return snapshot.ref.getDownloadURL();
    },
    (err) => { // onError (although I would just omit this entirely)
      console.log("failed to upload", err);
      throw err;
    }
  );

使用您的原始代码，如果getDownloadURL()失败，其错误将不会被处理。

如果您仍然需要进度报告，请使用：

const uploadTask = wmyRef.put(file, { customMetadata: metadata });

uploadTask.on(
  "state_changed",
  (snapshot) => {
    const progress = (snapshot.bytesTransferred / snapshot.totalBytes) * 100;
    console.log("Upload is " + progress + "% done");            
  }
);

return uploadTask
  .then(snapshot => {
    console.log("Upload is complete");
    return snapshot.ref.getDownloadURL()
  });