I am developing an app that the users can upload and vote for TagImages, so what is needed is to when someone check into a TagTopic get the most popular images and the newest one, so to do this ranking operation.

How should I approach this?

CodePudding user response：

I think what you need is to use Firestore or Realtime, but in you case realtime would be better because the number of reads and writes, however, what you could do is to create an object for each image that contains the metadata about it like the number of votes, may be also down votes, who upload it, upload time, tags, or any things else you want. Then in you app or website you'll make a query that reads lets say top 5, and get them, then use the images names to get them from the cloud storage. For example:

images:{
    image1Name:{
      upvote: 10;
      downvote: 2;
      totolvote: 8;
      uploader: 'Remoo';
      uploadTime: '10:00:00AM 23/11/2021' //whatever the structure 
    }
}

Then you query them (this is Flutter example):

_firebaseDatabase
    .reference()
    .child("images")
    .orderByChild('totolvote')
    .limitToFirst(5)
    .once().then(()=>{...})

Then get image1Name from cloud storage.
But note you can only use one orderByChild with each query, on the other hand you can use multiple where in Firestore, but there will be more cost on the reads and writes. Eventually it up to you and how you structure it. Hope this work for you.