No value associated with key CodingKeys error - json

Question

I'm trying to retrieve json from the google books api
Here are my structs:
struct Book: Codable {
let volumeInfo: VolumeInfo
}
struct VolumeInfo: Codable {
let title: String
let authors: [String]
let publisher, publishedDate, description: String
}
and this is the code to decode my json:
var bookInfo = [Book]()
override func viewDidLoad() {
super.viewDidLoad()
if let url = URL(string: "https://www.googleapis.com/books/v1/volumes?q=harry+potter") {
URLSession.shared.dataTask(with: url) { data, response, error in
if let data = data {
do {
let parsedJSON = try JSONDecoder().decode(Book.self, from: data)
for books in self.bookInfo {
DispatchQueue.main.async {
print(books.volumeInfo.title)
}
}
} catch {
print(error)
}
}
}.resume()
}
}
and the error message I get is this:
keyNotFound(CodingKeys(stringValue: "volumeInfo", intValue: nil),
Swift.DecodingError.Context(codingPath: [], debugDescription: "No
value associated with key CodingKeys(stringValue: "volumeInfo",
intValue: nil) ("volumeInfo").", underlyingError: nil))

Answer 1

you are trying to decode a Book object, where you should be decoding the
API response, then extract the Books from that. This is why you are getting the error.
Try the following example code:
struct Book: Identifiable, Codable {
let id = UUID()
let volumeInfo: VolumeInfo
}
struct VolumeInfo: Codable {
let title, publishedDate: String
let authors: [String]?
let publisher, description: String?
}
struct ApiResponse: Codable {
let kind: String
let totalItems: Int
let items: [Book]
}
var bookInfo = [Book]()
override func viewDidLoad() {
super.viewDidLoad()
if let url = URL(string: "https://www.googleapis.com/books/v1/volumes?q=harry+potter") {
URLSession.shared.dataTask(with: url) { data, response, error in
if let data = data {
do {
let response = try JSONDecoder().decode(ApiResponse.self, from: data)
bookInfo = response.items
} catch {
print(error)
}
}
}.resume()
}
}