Exception when deserializing json

Question

I have 2 methods

public static string SerializeObject<T>(T value)
{
    if (value == null)
    {
        return null;
    }

    var dictionaryObject = new Dictionary<string, object> { { typeof(T).Name, value } };

    var jsonString = JsonConvert.SerializeObject(dictionaryObject);

    return jsonString;
}

and

public static T DeserializeObject<T>(string jsonString)
{
    var objectValue = JsonConvert.DeserializeObject<Dictionary<string, object>>(jsonString);
    return JsonConvert.DeserializeObject<T>(objectValue.Values.First().ToString());
}

When I deserialize a json string with type

ConcurrentDictionary<KeyValuePair<long, long>, IList<string>>

I have an exception:

Could not convert string '[1, 1]' to dictionary key type 'System.Collections.Generic.KeyValuePair`2[System.Int64,System.Int64]'. Create a TypeConverter to convert from the string to the key type object. Path '[1, 1]', line 2, position 12.

So Can someone show me the right code for it to work?

Here is my code:

var test = new ConcurrentDictionary<KeyValuePair<long, long>, IList<string>>();
test.TryAdd(new KeyValuePair<long, long>(1, 1), new List<string> { "Test" });

var se = SerializeObject(test);

var de = DeserializeObject<ConcurrentDictionary<KeyValuePair<long, long>, IList<string>>>(se);

You might need to explain a bit more about what you're trying to accomplish. Not sure what problem you're trying to solve with the Dictionary. — d512, Jun 08 '16 at 04:48
@ user1334007: I am trying deserialize a json string to a object that has type ConcurrentDictionary, IList> — Vũ Hoàng, Jun 08 '16 at 04:50
Just remove the Dictionary stuff, it's pointless. Also you have some rather strange data structures there, maybe try using a Class as a DTO (Data Transfer Object), it'll simplify down your code a bunch and make it more logical — Toxicable, Jun 08 '16 at 04:53

score 3 · Accepted Answer · edited May 23 '17 at 12:15

I'm not sure if this is the best solution, but, please, try this:

1) create ContractResolver as described in this topic.

class DictionaryAsArrayResolver : DefaultContractResolver
        {
            protected override JsonContract CreateContract(Type objectType)
            {
                if (objectType.GetInterfaces().Any(i => i == typeof(IDictionary) ||
                    (i.IsGenericType &&
                     i.GetGenericTypeDefinition() == typeof(IDictionary<,>))))
                {
                    return base.CreateArrayContract(objectType);
                }

                return base.CreateContract(objectType);
            }
        }

2) Change a bit your Serialize/Deserialize methods:

public static string SerializeObject<T>(T value, JsonSerializerSettings settings)
        {
            if (value == null)
            {
                return null;
            }

            var dictionaryObject = new Dictionary<string, object> { { typeof(T).Name, value } };
            var jsonString = JsonConvert.SerializeObject(dictionaryObject, settings);

            return jsonString;
        }

        public static T DeserializeObject<T>(string jsonString, JsonSerializerSettings settings)
        {
            var objectValue = JsonConvert.DeserializeObject<Dictionary<string, object>>(jsonString, settings);
            return JsonConvert.DeserializeObject<T>(objectValue.Values.First().ToString(), settings);
        }

3) Check the test:

[TestMethod]
        public void Test()
        {
            var test = new ConcurrentDictionary<KeyValuePair<long, long>, IList<string>>();
            test.TryAdd(new KeyValuePair<long, long>(1, 1), new List<string> { "Test" });

            JsonSerializerSettings settings = new JsonSerializerSettings();
            settings.ContractResolver = new DictionaryAsArrayResolver();

            var se = SerializeObject(test, settings);

            var de = DeserializeObject<ConcurrentDictionary<KeyValuePair<long, long>, IList<string>>>(se, settings);
        }

I hope, it helps =)

It worked, thanks for your solution :) @Johnny Svarog – Vũ Hoàng Jun 08 '16 at 06:40 — Vũ Hoàng, Jun 08 '16 at 06:40

Exception when deserializing json

1 Answers1