How to set a variable to multiple types in data model

Question

My app gets its data from an API endpoint.

The data is a Review and the model looks like this:

struct Review: Identifiable, Decodable {
    var id: Int
    var reviewable_type: String
    var score: Int?
    var reviewable: <THIS CAN BE A MOVIE, A SHOW OR AN EPISODE>
    var user: User
    var created_at: String?
    var created: String?
    var text: String?
}

As you can see the reviewable property can be of multiple types. How do I implement this? I have different data models for Movie, Show and Episode. Note: the reviewable_type holds the value of the type that's in the reviewable variable. I don't know if that helps.

I tried things with protocols and extensions, but can't seem to get it to work.

Answer 1

I like AntonioWar's answer if the objects all have the same fields, which they don't. Maybe it still works that way but it wasn't clear to me from his answer.

What I did to solve it was this: I created a Reviewable struct with all the fields from the Show, Episode and Movie structs:

struct Reviewable : Decodable {
    var id: Int
    var tmdb_id: Int?
    var name: String?
    var show_id: Int?
    var season: String?
    var number: String?
    var type: String?
    var airdate: String?
    var airtime: String?
    var airstamp: String?
    var average_rating: Float?
    var vote_average: String?
    var vote_count: String?
    var image_medium: String?
    var image_original: String?
    var summary: String?
    var watched_by_users: [User]?
    var show: Show?
    var comments_count: Int?
    var likes_count: Int?
    var episode_number: String?
    var new_airstamp: String?
    var backdrop_image: String?
    var poster_image: String?
    var likes: [Like]?
    var reviews: [Review]?
    var imdb_id: String?
    var adult: Int?
    var backdrop_path: String?
    var budget: String?
    var homepage: String?
    var original_language: String?
    var original_title: String?
    var tagline: String?
    var title: String?
    var overview: String?
    var popularity: String?
    var poster_path: String?
    var release_date: String?
    var trending: String?
    var revenue: String?
    var status: String?
    var movie_users: [MovieUser]?
    var tv_maze_id: Int?
    var tvrage_id: String?
    var thetvdb_id: String?
    var original_name: String?
    var language: String?
    var origin_country: String?
    var average_runtime: Int?
    var premiered: String?
    var schedule: String?
    var updated: String?
    var episodes: [Episode]?
    var tracked_by: [User]?
}

Then, I added this as the type in the Review struct:

struct Review: Identifiable, Decodable {
    var id: Int
    var reviewable_type: String
    var score: Int?
    var reviewable: Reviewable
    var user: User
    var created_at: String?
    var created: String?
    var text: String?
}

Then, I created extensions for the 3 Reviewable objects, with a function that converts the Reviewable to the Movie, Episode or Show:

extension Movie {
    static func fromReviewable(reviewable: Reviewable) -> Movie {
        let movie = Movie(
            id: reviewable.id,
            tmdb_id: reviewable.tmdb_id,
            imdb_id: reviewable.imdb_id,
            adult: reviewable.adult,
            backdrop_path: reviewable.backdrop_path,
            budget: reviewable.budget,
            homepage: reviewable.homepage,
            original_language: reviewable.original_language,
            original_title: reviewable.original_title,
            tagline: reviewable.tagline,
            title: reviewable.title,
            overview: reviewable.overview,
            popularity: reviewable.popularity,
            poster_path: reviewable.poster_path,
            release_date: reviewable.release_date,
            trending: reviewable.trending,
            revenue: reviewable.revenue,
            status: reviewable.status,
            vote_average: reviewable.vote_average,
            vote_count: reviewable.vote_count,
            likes: reviewable.likes,
            movie_users: reviewable.movie_users,
            reviews: reviewable.reviews,
            comments_count: reviewable.comments_count,
            likes_count: reviewable.likes_count
        )
        
        return movie
    }
}

Because I know which type it is from the reviewable_type variable on the Review, I can use this to decode it in to the right struct:

if(review.reviewable_type == "App\\Models\\Movie") {
    let movie = Movie.fromReviewable(reviewable: review.reviewable!)
} else if(review.reviewable_type == "App\\Models\\Show") {
    let show = Show.fromReviewable(reviewable: review.reviewable!)
} else if(review.reviewable_type == "App\\Models\\Episode") {
    let episode = Episode.fromReviewable(reviewable: review.reviewable!)
}

Maybe it is a very shabby way of doing it but this is what worked for me (and maybe someone else can use it).