Widget model

Widget.swift

enum Widget {
    case headerWidget(HeaderWidget)
    case cardWidget(CardWidget)
    case buttonWidget(ButtonWidget)
}

extension Widget: Decodable {
    enum `Type`: String, Decodable {
        case headerWidget = "HeaderWidget"
        case cardWidget = "CardWidget"
        case buttonWidget = "ButtonWidget"
    }
    
    enum CodingKeys: String, CodingKey {
        case type
    }
    
    init(from decoder: Decoder) throws {
        let container = try decoder.container(keyedBy: CodingKeys.self)
        let type = try container.decode(`Type`.self, forKey: .type)
        
        switch type {
        case .headerWidget:
            self = .headerWidget(try HeaderWidget(from: decoder))
        case .cardWidget:
            self = .cardWidget(try CardWidget(from: decoder))
        case .buttonWidget:
            self = .buttonWidget(try ButtonWidget(from: decoder))
        }
    }
}