Adding custom data to a firebase storage upload?

Question

I'm uploading files to firebase storage like so:

var storageRef = firebase.storage();
                var fileRef = storageRef.ref(file.name);
                fileRef.put(file)
                    .then(function (snapshot) {
                        console.log('Uploaded a blob or file!');
                        window.URL.revokeObjectURL(file.preview);
                    })

After the upload I have a firebase storage trigger:

export const processUploadedFile = functions.storage.object().onChange(event => {
}

What I want to do is upload some additional information with the original upload so that the processUploadedFile knows what to do with it (for example extract the file, move it to a special directory, etc, etc).

I tried using metadata like so:

        var newMetadata = {
            customMetadata: {
                "Test": "value"
            }
        }

fileRef.put(file, newMetadata)

But on the cloud storage trigger function I don't know how to get the metadata, I logged out fileMetaData like so:

file.getMetadata().then((metaData)=>console.log(metaData))

But did not see my metadata anywhere in there (or in fileMetaData[0].metadata which returned undefined)

Not sure how I can achieve this...

Answer 1

I believe there are some properties that cannot be changed as they are not writeable. However, if you indeed want to add a custom data to firebase storage, you can set custom metadata as an object containing String properties. For example:

 var myCustomMetadata = {
    customMetadata : {
     'file_name': 'this is the file name'
     }
   }

In the case above, the file_name is the custom metadata that you want to create.

After creating a reference to the file in the firebase storage, you can then call the updateMetadata() method on the reference.

For example:

Get the reference to an image file using downloadUrl:

  var getRef = firebase.storage().refFromURL(imageUrl);

Use the reference to update the metadata:

getRef.updateMetadata(myCustomMetadata).then(()=>{
    //do other things
  })

Answer 2

I think providing file meta info will do the trick. Here is the reference. Firebase Storage File metadata. You can pass custom parameters for the file with customMetadata. For instance :

customMetadata: {
    'actionType': 'ACTION_CODE',
    'action': 'do something info'
}

You can access this metadata with storage trigger and take the action accordingly. Here is how you can achieve that Automatically Extract Images Metadata