JSON array of mixed types using JSONDecoder

Question

I have JSON Structure

Code Block [
	{
		name: "Boo",
		title: "Hello Boo",
		value: [
			subject: 88
		]
	},
	{
		name: "Foo",
		title: "Hello Foo",
	}
]

for decoding Purpose i performed this

Code Block struct Students: Decodable {
	let name: String,
	let title: String,
	let value: ValueHeader
}
struct ValueHeader: Decodable {
	let subject: Int?
}

Code Block fileprivate func fetchTaskItems(completion: @escaping (Result<[Students], Error>) -> ()) {
guard let url = URL(string: jsonString) else { return }
     
URLSession.shared.dataTask(with: url) { (data, response,err) in
       
      if let err = err {
        completion(.failure(err))
        return
      }
       
      do {
        let taskItem = try JSONDecoder().decode([Students].self, from: data!)
        completion(.success(taskItem))
      } catch let jsonError {
        completion(.failure(jsonError))
      }
       
    }.resume()
     
  }

i get an error as

Code Block valueNotFound(Swift.KeyedDecodingContainer<App.ValueHeader.(unknown context at $10fd991dc).CodingKeys>,

I tried giving an optional to subject still not working any idea how to deal with this type of JSON

1.9k

Posted by

aamirkhan

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Answer 1

Your JSON Structure is not a valid JSON.
Especially this part:

Code Block [
		subject: 88
]

In JSON, [ ] is a JSON array and cannot contain a element like subject: 88.
(More precisely, even in JSON object, that should be "subject": 88.)

I cannot reproduce the error valueNotFound with your JSON Structure and your code.
Please show the right structure of your JSON.

Posted by

OOPer

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JSON array of mixed types using JSONDecoder

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