Codable protocol error "The given data was not valid JSON." - ios

Question

I am getting an error having to do with the codable protocol
struct UsersResponse : Codable {
let directoryItems: [DirectoryItem]
enum CodingKeys : String, CodingKey {
case directoryItems = "directory_items"
}
}
struct DirectoryItem : Codable {
let user : User
}
struct User : Codable {
let id: Int
let userName: String
let imageURL: String
enum CodingKeys : String, CodingKey {
case id = "id"
case userName = "username"
case imageURL = "avatar_template"
}
}
This is my JSON response on Postman, the keys are well defined in the protocol, honestly I don't really know what is going wrong.
Here is the full error object.
dataCorrupted(Swift.DecodingError.Context(codingPath: [], debugDescription: "The given data was not valid JSON.", underlyingError: Optional(Error Domain=NSCocoaErrorDomain Code=3840 "Invalid value around character 0." UserInfo={NSDebugDescription=Invalid value around character 0.})))
{
"directory_items": [
{
"id": 0,
"likes_received": 0,
"likes_given": 0,
"topics_entered": 0,
"topic_count": 0,
"post_count": 0,
"posts_read": 0,
"days_visited": 0,
"user": {
"id": 0,
"username": "string",
"avatar_template": "string",
"name": "string",
"title": { }
}
}
],
"total_rows_directory_items": 0,
"load_more_directory_items": "string"
}
This is where I ask for the data
func send<T: APIRequest>(request: T, completion: #escaping(Result<T.Response, Error>) -> ()) {
let request = request.requestWithBaseUrl()
let task = session.dataTask(with: request) { data, response, error in
do {
guard let response = response as? HTTPURLResponse else { return }
if response.statusCode >= 400 && response.statusCode < 500 {
if let data = data {
let errorModel = try JSONDecoder().decode(DiscourseAPIError.self, from: data)
DispatchQueue.main.async {
let errorString = errorModel.errors?.joined(separator: ", ") ?? "Unknown error"
completion(.failure(NSError(domain: "request error", code: 0, userInfo: [NSLocalizedDescriptionKey: errorString])))
}
} else {
DispatchQueue.main.async {
completion(.failure(SessionAPIError.emptyData))
}
}
}
if let data = data {
let json = try JSONSerialization.jsonObject(with: data) as! Dictionary<String, AnyObject>
print(json)
let model = try JSONDecoder().decode(T.Response.self, from: data)
DispatchQueue.main.async {
completion(.success(model))
}
} else {
DispatchQueue.main.async {
completion(.failure(SessionAPIError.emptyData))
}
}
} catch {
DispatchQueue.main.async {
print(error)
completion(.failure(error))
}
}
}
task.resume()
}
}

Answer 1

In a playground, I copied your sample json and got this output:
let sample = """
{
"directory_items": [
{
"id": 0,
"likes_received": 0,
"likes_given": 0,
"topics_entered": 0,
"topic_count": 0,
"post_count": 0,
"posts_read": 0,
"days_visited": 0,
"user": {
"id": 0,
"username": "string",
"avatar_template": "string",
"name": "string",
"title": { }
}
}
],
"total_rows_directory_items": 0,
"load_more_directory_items": "string"
}
""".data(using: .utf8)!
let json = try! JSONSerialization.jsonObject(with: sample, options: [])
print(json)
//{
// "directory_items" = (
// {
// "days_visited" = 0;
// id = 0;
// "likes_given" = 0;
// "likes_received" = 0;
// "post_count" = 0;
// "posts_read" = 0;
// "topic_count" = 0;
// "topics_entered" = 0;
// user = {
// "avatar_template" = string;
// id = 0;
// name = string;
// title = {
// };
// username = string;
// };
// }
// );
// "load_more_directory_items" = string;
// "total_rows_directory_items" = 0;
//}
The json is definitely valid. I'd be willing to bet that the suggested comment by Paulw11 is absolutely on point. There's probably a leading value that's breaking the rest of the JSON.
A potential simple way to clean it up would be to convert to a utf8 string and back to data, but that's more cpu cycles than necessary, especially if this is a frequently run code snippet.
There would be other, more efficient ways to clean it up, but this would at least let you confirm if this is a valid path forward or not.
(ps. please don't judge my force unwraps! it's just a playground and proof of concept!)