How to get download urls of resized images from cloud function

[Joe Hill]

My code goes likes so

Upload a file to storage

Create a doc with the files download url to ('userUID/gallery/randomId') 

A cloud function then runs a function onFinalize() that resizes the image

Here is where I am suck. How can I get the download urls of those images and store them in my doc that contains the original files download url I want to end up with my doc looking like so

{

  originalFile: 'url'

  resizedUrls: ['400x400','800x800', 'etc']
}

I have no way of referencing the doc which has the random id

You can see what I am trying to get here. Create a gallery with thumbnails. 

Thanks Joe

[Doug Stevenson]

I think you might be helped by this: https://stackoverflow.com/questions/42956250/get-download-url-from-file-uploaded-with-cloud-functions-for-firebase

Doug