How to get a Firestore document size?

Question

From Firestore docs, we get that the maximum size for a Firestore document is:

Maximum size for a document 1 MiB (1,

Answer 1

For Swift users,

If you want to estimate the document size then I use the following. Returns the estimated size of document in Bytes. It's not 100% accurate but gives a solid estimate. Basically just converts each key, value in the data map to a string and returns total bytes of String + 1. You can see the following link for details on how Firebase determines doc size: https://firebase.google.com/docs/firestore/storage-size.

func getDocumentSize(data: [String : Any]) -> Int{
        
        var size = 0
        
        for (k, v) in  data {
            
            size += k.count + 1
            
            if let map = v as? [String : Any]{
                size += getDocumentSize(data: map)
            } else if let array = v as? [String]{
                for a in array {
                    size += a.count + 1
                }
            } else if let s = v as? String{
                size += s.count + 1
            }
    
        }
        
        return size
        
    }