Handling JSON single object and array

Question

I'm using Newtonsoft.Json to work with some JSON data that is being returned to me. Depending on what I request I can either get back something that looks like:

{
"TotalRecords":2,
"Result":
    [
        {
        "Id":24379,
        "AccountName":"foo"
        },
        {
        "Id":37209,
        "AccountName":"bar"
        }
    ],
"ResponseCode":0,
"Status":"OK",
"Error":"None"
}

or

{
    "Result":
    {
        "Id":24379,
        "AccountName":"foo"
    },
    "ResponseCode":0,
    "Status":"OK",
    "Error":"None"
}

So sometimes "Result" is an array of Results or "Result" could be a single response.

I've tried using the answer from How to handle both a single item and an array for the same property using JSON.net but I still get errors.

In particular I'm getting a

Newtonsoft.json.jsonSerializationException: 'Cannot deserialize the current JSON object (e.g. {"name":"value"}) into type 'System.Collections.Generic.List'...

Custom converter looks like:

public class SingleOrArrayConverter<T> : JsonConverter
    {
        public override bool CanConvert(Type objecType)
        {
            return (objecType == typeof(List<T>));
        }

        public override object ReadJson(JsonReader reader, Type objecType, object existingValue,
            JsonSerializer serializer)
        {
            JToken token = JToken.Load(reader);
            if (token.Type == JTokenType.Array)
            {
                return token.ToObject<List<T>>();
            }
            return new List<T> { token.ToObject<T>() };
        }

        public override bool CanWrite
        {
            get { return false; }
        }

        public override void WriteJson(JsonWriter writer, object value, JsonSerializer serializer)
        {
            throw new NotImplementedException();
        }
    }

My response class(es) look like

public class TestResponse
    {
        [JsonProperty("Result")]
        [JsonConverter(typeof(SingleOrArrayConverter<string>))]
        public List<DeserializedResult> Result { get; set; }
    }
public class DeserializedResult
    {
        public string Id { get; set; }
        public string AccountName { get; set; }
    }

And finally my request looks like

List<TestResponse> list = JsonConvert.DeserializeObject<List<TestResponse>>(response.Content);

Answer 1

Your code is fine, it just needs a few type tweaks.

This line

List<TestResponse> list = JsonConvert.DeserializeObject<List<TestResponse>>(response.Content);

needs to be like this, because your response is an object, not a List.

TestResponse list = JsonConvert.DeserializeObject<TestResponse>(response);

Then your custom deserializer attribute:

[JsonConverter(typeof(SingleOrArrayConverter<string>))]

needs to become:

[JsonConverter(typeof(SingleOrArrayConverter<DeserializedResult>))]

because your Result object is not a string or an array of strings, it's either an array of DeserializedResults or a DeserializedResult.

Answer 2

I think, that there is no way to understend which type of response do you have due desirialization. Thats why i propose to check manualy type of response:

using System;
using System.Collections.Generic;
using Newtonsoft.Json;

namespace TestConsoleApp
{
    public class Class1
    {

        public class Result
        {
            public int Id { get; set; }
            public string AccountName { get; set; }
        }

        public class ModelWithArray
        {
            public int TotalRecords { get; set; }
            public List<Result> Result { get; set; }
            public int ResponseCode { get; set; }
            public string Status { get; set; }
            public string Error { get; set; }
        }

        public class Result2
        {
            public int Id { get; set; }
            public string AccountName { get; set; }
        }

        public class ModelWithoutArray
        {
            public Result2 Result { get; set; }
            public int ResponseCode { get; set; }
            public string Status { get; set; }
            public string Error { get; set; }
        }

        public static void Main(params string[] args)
        {
            //string json = "{\"TotalRecords\":2,\"Result\":[{\"Id\":24379,\"AccountName\":\"foo\"},{\"Id\":37209,\"AccountName\":\"bar\"}], \"ResponseCode\":0,\"Status\":\"OK\",\"Error\":\"None\"}";
            string json = "{\"Result\":{\"Id\":24379,\"AccountName\":\"foo\"},\"ResponseCode\":0,\"Status\":\"OK\",\"Error\":\"None\"}";

            if (checkIsArray(json))
            {
                ModelWithArray data = JsonConver.DeserializeObject<ModelWithArray >(json);
            }else
            {
                ModelWithoutArray data = JsonConver.DeserializeObject<ModelWithoutArray>(json);
            }

        }

        static bool checkIsArray(string json)
        {

            Dictionary<string, object> desData = JsonConvert.DeserializeObject<Dictionary<string, object>>(json);

            if (desData["Result"].GetType().Name.Contains("Array"))
            {
                return true;
            }
            else
            {
                return false;
            }

        }

    }
}