Firebase.swift

import Foundation
import FirebaseDatabase
import Result

public typealias DecodeResult<T> = Result<T, DecodeError>

public enum DecodeError: Error {
    case noValuePresent
    case conversionError(Error)
}

extension DataSnapshot {
    func decoded<T>() -> DecodeResult<T> where T: Decodable {
        guard exists(), let value = value else {
            return Result.failure(DecodeError.noValuePresent)
        }
        let decoder = StructureDecoder()
        do {
            let d = try decoder.decode(T.self, from: value)
            return Result.success(d)
        } catch {
            return Result.failure(DecodeError.conversionError(error))
        }
    }
}