如何避免在云存储事件中对文件夹执行Firebase功能

Question

I'm trying to organize assets(images) into folders with a unique id for each asset, the reason being that each asset will have multiple formats (thumbnails, and formats optimized for web and different viewports).

So for every asset that I upload to the folder assets-temp/ is then moved and renamed by the functions into assets/{unique-id}/original{extension} .

example: assets-temp/my-awesome-image.jpg should become assets/489023840984/original.jpg .

note: I also keep track of the files with their original name in the DB and in the original's file metadata.

The issue : The function runs and performs what I want, but it also adds a folder named assets/{uuid}/original/ with nothing in it...

The function:

exports.process_new_assets = functions.storage.object().onFinalize(async (object) => {
  // Run this function only for files uploaded to the "assets-temp/" folder.
  if (!object.name.startsWith('assets-temp/')) return null;

  const file = bucket.file(object.name);
  const fileExt = path.extname(object.name);
  const destination = bucket.file(`assets/${id}/original${fileExt}`);
  const metadata = {
    id,
    name: object.name.split('/').pop()
  };

  // Move the file to the new location.
  return file.move(destination, {metadata});
});

Answer 1

I am guessing that this might happen if the operation of uploading the original image triggers two separate events: one that creates the directory assets-temp and one that creates the file assets-temp/my-awesome-image.jpg.

If I guessed right, the first operation will trigger your function with a directory object (named "assets-temp/" ). This matches your first if , so the code will proceed and do

destination = bucket.file('assets/${id}/original') // fileExt being empty

and then call file.move - this will create assets/id/original/ directory.

Simply improve your 'if' to exclude a file named "assets-temp/".

Answer 2

According to the documentation there is no such thing as folders in cloud storage, however, it is possible to emulate them, like you can do by using the console GUI. When creating folders what really happens is that an empty object is created(zero bytes of space) but its name ends with a forward slash, also folder names can end with _$folder$ but it is my understanding that that is how things worked in older versions so for newer buckets the forward slash is enough.