how to get Json values which are not in a class using C#?

April 27, 2022

I have the following problem:
I am a C# beginner and I want to create a weather app using the OpenWeatherApi.
The response of the api looks like this (it´s just an example):
[
{
"name": "London",
"lat": 51.5085,
"lon": -0.1257,
"country": "GB"
},
I want to get the lat and lon values.
My C# code looks like this:

public class CoordinatesResponse
{
    public double Lat { get; set; }
    public double Lon { get; set; }
}

private static string _coordinatesResponse;

static void ExtractCoordinatesFromJson()
    {
        CoordinatesResponse coordinatesresponse = JsonConvert.DeserializeObject<CoordinatesResponse>(_coordinatesResponse);
        Console.WriteLine(coordinatesresponse.Lat);
        Console.WriteLine(coordinatesresponse.Lon);
    }

My error is the following:
Unhandled exception. Newtonsoft.Json.JsonSerializationException: Cannot deserialize the current JSON array (e.g. [1,2,3]) into type ‘WeatherApp.CoordinatesResponse’ because the type requires a JSON object (e.g. {"name":"value"}) to deserialize correctly.
To fix this error either change the JSON to a JSON object (e.g. {"name":"value"}) or change the deserialized type to an array or a type that implements a collection interface (e.g. ICollection, IList) like List that can be deserialized from a JSON array. JsonArrayAttribute can also be added to the type to force it to deserialize from a JSON array.
What do I wrong?

>Solution :

Your problem is in the type. Been an array, you must use List<CoordinatesResponse>:

static void ExtractCoordinatesFromJson()
{
    var coordinatesresponses = JsonConvert.DeserializeObject<List<CoordinatesResponse>>(_coordinatesResponse);
    foreach (var coordinatesresponse in coordinatesresponses)
    {
        Console.WriteLine(coordinatesresponse.Lat);
        Console.WriteLine(coordinatesresponse.Lon);
    }
}