Is there a way to prevent duplicate image upload to firebase storage

3
votes

I have a requirement where my app will allow users to upload images. Is there a functionality in firebase storage where I can prevent duplicates and use the old image url when the user/some other user is trying to load the same image.

1
firebasefirebase-storage

1 Answers

2
votes

Yes. Hash the image and store the file using that name. Write a rule that doesn't allow overwriting of a file.

// Upload the file on the client to a file named after a hash of the data
var string = 'Hello, world!'
firebase.storage().ref().child('images/' + hash(string)).putString(string);

var hash = function(string) { /* SHA1, MD5, etc. (note: collisions exist for certain algorithms ) */ }


// Rules
service firebase.storage {
  match /b/{bucket}/o {
    match /images/{imageHash} {
      // only allow create and delete, not overwrite
      allow write: if resource == null || request.resource == null
    }
  }
}