Complex JSON to Swift - json

Question

So I am relatively new to JSON and converting it to Swift. I have only dealt with basic JSON with simple data types. Nothing fancy. I also have only dealt with using JSON that I have created.
Now I am trying to use JSON that I have gathered from and API. This JSON has nested objects inside of other objects.
here is the format of the JSON:
{
"records": [
{
"id": "Info",
"fields": {
"Card Name": "Info",
"Qty": 0,
"Card Type": "Info",
"Color": "Info",
"Card #": "Info",
"Rarity": "Info",
"Image": [
{
"id": "Info",
"url": "url",
"filename": "info",
"size": 0,
"type": "info",
"thumbnails": {
"small": {
"url": "url",
"width": 0,
"height": 0
},
"large": {
"url": "url",
"width": 0,
"height": 0
},
"full": {
"url": "url",
"width": 0,
"height": 0
}
}
}
],
"Level": 0,
"Full Set": 0
},
"createdTime": "info"
}
],
"offset": "info"
}
I am not sure if I need to do anything with the "records": portion. Now there are more records within the "records": array.
I don't need all of the information within each record.
I tried doing something like:
struct Card {
let offSet: String
let cardName: String
}
extension Card: Decodable {
enum CodingKeys: String, CodingKey {
case offSet
case cardName
enum FieldKeys: String, CodingKey {
case cardName = "Card Name"
}
}
init(from decoder: Decoder) throws {
let container = try decoder.container(keyedBy: CodingKeys.self)
offSet = try container.decode(String.self, forKey: .offSet)
let fieldContainer = try container.nestedContainer(keyedBy: CodingKeys.FieldKeys.self, forKey: .cardName)
cardName = try fieldContainer.decode(String.self, forKey: .cardName)
}
}
Every time I try to decode the info into my Swift Struct it just comes up nil. Not sure what I am doing wrong or where to go from here. I haven't dealt with JSON that have "records": setup like this. Not sure if this even matters.
Also a side question in regards to images. Would I just use the url property to display the image? The image files will be PNG. Never dealt with images and JSON before.

Answer 1

As Larme commented "Your code can't guess" - Meaning you need to represent the same structure in code as your JSON provides.
In danger of doing the work for you I've written a very verbose set of Codable struct's that pull out all of the data from the JSON you provided.
struct Card: Codable {
var records:[Record]
var offset:String
}
struct Record: Codable {
var id:String
var fields:Fields
var createdTime:String
}
struct Fields: Codable {
var name:String
var quantity:Int
var type:String
var color:String
var number:String
var rarity:String
var level:Int
var fullSet:Int
var image:[Image]
enum CodingKeys: String, CodingKey {
case name = "Card Name"
case quantity = "Qty"
case type = "Card Type"
case color = "Color"
case number = "Card #"
case rarity = "Rarity"
case level = "Level"
case fullSet = "Full Set"
case image = "Image"
}
}
struct Image: Codable {
var id:String
var url:String
var filename:String
var size:Int
var type:String
var thumbnails:Thumbnails
}
struct Thumbnails: Codable {
var small:Thumbnail
var large:Thumbnail
var full:Thumbnail
}
struct Thumbnail: Codable {
var url:String
var width:Int
var height:Int
}
I tested the above in a playground by pasting the JSON you provided as a multiline string and using the following to dump the resulting objects.
do {
if let data = json.data(using: .utf8) {
let card = try JSONDecoder().decode(Card.self, from: data)
dump(card)
}
} catch {
fatalError("Failed to decode \(error)")
}
The output of which was:
▿ __lldb_expr_21.Card
▿ records: 1 element
▿ __lldb_expr_21.Record
- id: "Info"
▿ fields: __lldb_expr_21.Fields
- name: "Info"
- quantity: 0
- type: "Info"
- color: "Info"
- number: "Info"
- rarity: "Info"
- level: 0
- fullSet: 0
▿ image: 1 element
▿ __lldb_expr_21.Image
- id: "Info"
- url: "url"
- filename: "info"
- size: 0
- type: "info"
▿ thumbnails: __lldb_expr_21.Thumbnails
▿ small: __lldb_expr_21.Thumbnail
- url: "url"
- width: 0
- height: 0
▿ large: __lldb_expr_21.Thumbnail
- url: "url"
- width: 0
- height: 0
▿ full: __lldb_expr_21.Thumbnail
- url: "url"
- width: 0
- height: 0
- createdTime: "info"
- offset: "info"
Once you have all the data you could start simplifying things, perhaps an extension to the Card that gets the first records name.
extension Card {
var cardName:String {
guard let firstRecord = self.records.first else {
return "Unknown Name"
}
return firstRecord.fields.name
}
}
print(card.cardName) // "Info\n"