Swift Codable null handling

Question

I have a struct that parse JSON using Codable.

struct Student: Codable {
    let name: String?
    let amount: Double?
    let adress: String?
}

Now if the amount value is coming as null the JSON parsing is failing.

So should I manually handle the null cases for all the Int and Double that are present in the Student struct?

The String values coming as null is automatically handled.

Answer 1

Let me do this Playground for you since an example shows you more than a hundred words:

import Cocoa

struct Student: Codable {
    let name: String?
    let amount: Double?
    let adress: String?
}

let okData = """
 {
  "name": "here",
  "amount": 100.0,
  "adress": "woodpecker avenue 1"
 }
 """.data(using: .utf8)!

let decoder = JSONDecoder()
let okStudent = try decoder.decode(Student.self, from:okData)
print(okStudent)

let nullData = """
 {
 "name": "there",
 "amount": null,
 "adress": "grassland 2"
 }
 """.data(using: .utf8)!

let nullStudent = try decoder.decode(Student.self, from:nullData)
print(nullStudent)

null is handled just fine if you define your structs using optionals. I would however advise against it if you can avoid it. Swift provides the best support I know to help me not forgetting to handle nil cases wherever they may occur, but they are still a pain in the ass.