Error decoding JSON - keyNotFound(CodingKeys - json

Question

When I try to decode this json:
"polls": [
{
"title": "title",
"date": "date",
"summary": "summary",
"stats": {
"total": {
"dagegen gestimmt": 139,
"nicht beteiligt": 114,
"dafür gestimmt": 454,
"enthalten": 2
},
}
}, /*<and about 76 of this>*/ ]
with this Codable:
struct poll: Codable {
var stats: stats
var title: String?
var date: String?
var summary: String?
struct stats: Codable {
var total: total
struct total: Codable {
var nays: Int
var yays: Int
var nas: Int
var abstentions: Int
private enum CodingKeys: String, CodingKey {
case yays = "dafür gestimmt"
case nays = "dagegen gestimmt"
case nas = "nicht beteiligt"
case abstentions = "enthalten"
}
}
}
}
I get the following error
keyNotFound(CodingKeys(stringValue: "dagegen gestimmt", intValue: nil)(if you need the full error text tell me)
I tried some of the answer from similar questions but nothing worked.

Answer 1

You apparently have occurrences of total where dagegen gestimmt is absent. So, make that an Optional, e.g. Int?:
struct Poll: Codable {
let stats: Stats
let title: String?
let date: Date?
let summary: String?
struct Stats: Codable {
let total: Total
struct Total: Codable {
let nays: Int?
let yays: Int?
let nas: Int?
let abstentions: Int?
private enum CodingKeys: String, CodingKey {
case yays = "dafür gestimmt"
case nays = "dagegen gestimmt"
case nas = "nicht beteiligt"
case abstentions = "enthalten"
}
}
}
}
I’d also suggest the following, also reflected in the above:
Start type names (e.g. your struct names) with uppercase letter;
Use let instead of var as we should always favor immutability unless you really are going to be changing these values within this struct; and
If your date is in a consistent format, I’d suggest making the date a Date type, and then you can supply the JSONDecoder a dateDecodingStrategy that matches (see sample below).
For example:
let data = """
{
"polls": [
{
"title": "New Years Poll",
"date": "2019-01-01",
"summary": "summary",
"stats": {
"total": {
"dagegen gestimmt": 139,
"nicht beteiligt": 114,
"dafür gestimmt": 454,
"enthalten": 2
}
}
},{
"title": "Caesar's Last Poll",
"date": "2019-03-15",
"summary": "summary2",
"stats": {
"total": {
"dafür gestimmt": 42
}
}
}
]
}
""".data(using: .utf8)!
struct Response: Codable {
let polls: [Poll]
}
do {
let decoderDateFormatter = DateFormatter()
decoderDateFormatter.dateFormat = "yyyy-MM-dd"
decoderDateFormatter.locale = Locale(identifier: "en_US_POSIX")
let userInterfaceDateFormatter = DateFormatter()
userInterfaceDateFormatter.dateStyle = .long
let decoder = JSONDecoder()
decoder.dateDecodingStrategy = .formatted(decoderDateFormatter)
let response = try decoder.decode(Response.self, from: data)
let polls = response.polls
for poll in polls {
print(poll.title ?? "No title")
print(" date:", poll.date.map { userInterfaceDateFormatter.string(from: $0) } ?? "No date supplied")
print(" yays:", poll.stats.total.yays ?? 0)
print(" nays:", poll.stats.total.nays ?? 0)
}
} catch {
print(error)
}
That produces:
New Years Poll
date: January 1, 2019
yays: 454
nays: 139
Caesar's Last Poll
date: March 15, 2019
yays: 42
nays: 0

Answer 2

Set your model as per following format. Also check datatype as per your response.
struct PollsModel:Codable{
var polls : [PollsArrayModel]
enum CodingKeys:String, CodingKey{
case polls
}
struct PollsArrayModel:Codable{
var title : String?
var date : String?
var summary : String?
var stats : PollsStatsModel
enum CodingKeys:String, CodingKey{
case title
case date
case summary
case stats
}
struct PollsStatsModel:Codable{
var total : PollsStatsTotalModel
enum CodingKeys:String, CodingKey{
case total
}
struct PollsStatsTotalModel:Codable{
var dagegen_gestimmt : Int?
var nicht_beteiligt : Int?
var dafür_gestimmt : Int?
var enthalten : Int?
enum CodingKeys:String, CodingKey{
case dagegen_gestimmt = "dagegen gestimmt"
case nicht_beteiligt = "nicht beteiligt"
case dafür_gestimmt = "dafür gestimmt"
case enthalten = "enthalten"
}
}
}
}
}