Vũ Hoàng Vũ Hoàng - 5 months ago 42
JSON Question

Exception when deserializing json

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);

Answer

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 =)

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