Deserialize list of lists in C#

Question

I have the following response from an API

[[{\"message\":\"example message\"}]]

I tried to deserialize it as a list of lists as follow

public class ErrorMessage
{
    [JsonProperty("message")]
    public string Message;
}
public class ErrorMessages
{
    public List<ErrorMessage> Messages;
}
public class ErrorMessagesList
{
    public List<ErrorMessages> MessagesList;
}

The deserialization fails, how can I deserialize it?

Answer 1

This code works for me:

 var someJson = "[[{\"message\":\"example message\"}]]";
 var result = JsonConvert.DeserializeObject<List<List<ErrorMessage>>>(someJson);
 Debug.Assert(result.First().First().Message == "example message");

You have a collection of a collection of instances of your ErrorMessage class. In the code, I deserialize into a List of a List of ErrorMessage. So the first item in result is a List of ErrorMessage. The first item in that list is an ErrorMessage, and the Message property of that object is "example message".

If your JSON looked like this, it would still deserialize with that DeserializeObject call, but it would be more obvious what you were looking at:

var moreJson = @"[
                    [
                        {""message"": ""First message""},
                        {""message"": ""Second message""},
                        {""message"": ""Third message""}
                    ],
                    [
                        {""message"": ""Fourth message""},
                        {""message"": ""Fifth message""}
                    ]
                ]";

The List of list of ErrorMessage is more obvious in this code. But, it's the same type in both examples