Artist.swift

extension Artist {
    convenience init?(json: [String: Any]) {
        
        struct Key {
            static let artistName = "artistName"
            static let artistId = "artistId"
            static let primaryGenreId = "primaryGenreId"
        }
        
        guard let artistName = json[Key.artistName] as? String,
            let artistId = json[Key.artistId] as? Int,
            let primaryGenreId = json[Key.primaryGenreId] as? Int,
            let primaryGenreValue = Genre(rawValue: primaryGenreId) else {
                return nil
        }
        
        self.init(id: artistId, name: artistName, primaryGenre: primaryGenreValue, albums: [])
    }
}