Swift can't access part of JSON response with enum initializer - json

Question

I have trouble accessing a part of a JSON response.
(part of)The Source:
{
"time":1552726518,
"result":"success",
"errors":null,
"responce":{
"categories":{
"1":{
"nl":{
"name":"New born",
"description":"TEST",
"children":[
{
"name":"Unisex",
"description":"TESTe",
"children":[
{
"name":"Pants",
"description":"TEST",
"children":false
}
]
}
]
}
}
}
}
}
Approach
As you can see the source can have multiple categories. A single categorie will have a 'name', 'description' and may have 'children'. Children wil have a 'name', 'description' and also may have 'children'. This might go endless. If there are no children the SJON statement is 'false'
I use the website: https://app.quicktype.io to generate a junk of code to parse the JSON. I modified the result, because the website doesn't know that the children can go endless:
struct ProductCategories: Codable {
let time: Int?
let result: String?
let errors: [String]?
let responce: ProductCategoriesResponce?
init(time: Int? = nil, result: String? = nil, errors: [String]? = nil, responce: ProductCategoriesResponce? = nil) {
self.time = time
self.result = result
self.errors = errors
self.responce = responce
}
}
struct ProductCategoriesResponce: Codable {
let categories: [String: Category]?
}
struct Category: Codable {
let nl, en: Children?
}
struct Children: Codable {
let name, description: String?
let children: EnChildren?
}
enum EnChildren: Codable {
case bool(Bool)
case childArray([Children])
init(from decoder: Decoder) throws {
let container = try decoder.singleValueContainer()
if let x = try? container.decode(Bool.self) {
self = .bool(x)
return
}
if let x = try? container.decode([Children].self) {
self = .childArray(x)
return
}
throw DecodingError.typeMismatch(EnChildren.self, DecodingError.Context(codingPath: decoder.codingPath, debugDescription: "Wrong type for EnChildren"))
}
func encode(to encoder: Encoder) throws {
var container = encoder.singleValueContainer()
switch self {
case .bool(let x):
try container.encode(x)
case .childArray(let x):
try container.encode(x)
}
}
}
And I can decode de data with:
productCategories = try JSONDecoder().decode(ProductCategories.self, from: jsonData!)
This part works fine. I can access "New Born", but can't get access his children.
I search a long time for the answer I tried so much. To much to all share here. What I expect to get access is:
if let temp = productCategories.responce?.categories?["\(indexPath.item)"]?.nl?.children! {
let x = temp(from: Decoder)
but this will trow me an error:
"Cannot call value of non-function type 'EnChildren'"
also code like:
let temp1 = productCategories.responce?.categories?["\(indexPath.item)"]?.nl?.children
Won't get me anywhere.
So, any ideas? Thank you.

Answer 1

First of all: If you are responsible for the server side, send null for the leaf children or omit the key rather than sending false. It makes the decoding process so much easier.
app.quicktype.io is a great resource but I disagree with its suggestion.
My solution uses a regular struct Children with a custom initializer. This struct can be used recursively.
The key children is decoded conditionally. First decode [Children], on failure decode Bool and set children to nil or hand over the error.
And I declared struct members as much as possible as non-optional
struct Response: Decodable {
let time: Date
let result: String
let errors: [String]?
let responce: ProductCategories
}
struct ProductCategories: Decodable {
let categories: [String: Category]
}
struct Category: Decodable {
let nl: Children
}
struct Children: Decodable {
let name, description: String
let children : [Children]?
private enum CodingKeys : String, CodingKey { case name, description, children }
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
name = try container.decode(String.self, forKey: .name)
description = try container.decode(String.self, forKey: .description)
do {
children = try container.decode([Children].self, forKey: .children)
} catch DecodingError.typeMismatch {
_ = try container.decode(Bool.self, forKey: .children)
children = nil
}
}
}
In the root object the key time can be decoded to Date if you specify an appropriate date decoding strategy
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .secondsSince1970
let result = try decoder.decode(Response.self, from: jsonData!)
And you can access for example the name Unisex with
result.responce.categories["1"]?.nl.children?[0].name