How do you prepare a model to encode properly - json

Question

API Objects
Types of JSON objects served by Gutendex are given below.
Book
{
"id": <number of Project Gutenberg ID>,
"title": <string>,
"subjects": <array of strings>,
"authors": <array of Persons>,
"translators": <array of Persons>,
"bookshelves": <array of strings>,
"languages": <array of strings>,
"copyright": <boolean or null>,
"media_type": <string>,
"formats": <Format>,
"download_count": <number>
}
Format
{
<string of MIME-type>: <string of URL>,
...
}
Person
{
"birth_year": <number or null>,
"death_year": <number or null>,
"name": <string>
}
There is an API service that returns the types above. I managed to create objects for Book and person on swift but I don't know how to implement a codable struct for "Format"

Answer 1

Codable is a protocol you can conform your struct or class to that handles this for you. The JSON key defaults to the field name, however, you can override it with a coding key. This is a pretty close representation of what you're looking for, however, the formats field was a little ambiguous.
struct Book: Codable {
let id: Int
let title: String
let subjects: [String]
let authors: [Person]
let translators: [Person]
let bookshelves: [String]
let languages: [String]
let copyright: Bool?
let mediaType: String
let numberOfDownloads: Int
let formats: [String : String] // This wasn't clear in your example
enum CodingKeys: String, CodingKey {
case id, title, subjects, authors, translators, bookshelves,
languages, copyright, formats // No need to override the key
case mediaType = "media_type"
case numberOfDownloads = "download_count"
}
struct Person: Codable {
let birthYear: Int?
let deathYear: Int?
let name: String
enum CodingKeys: String, CodingKey {
case name // No need to override the key
case birthYear = "birth_year"
case deathYear = "death_year"
}
}