using System;

using System.Collections;

using System.Collections.Generic;

using System.Reflection;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

using Newtonsoft.Json.Serialization;

public class Program

{

    public static void Main()

    {

        var item1 = new DatamapItem();

        item1.datamapKey.Add("module", 1);

        item1.datamapKey.Add("id", 1391);

        item1.DatamapItemFields.Add("paramName", "VE8321C");

        item1.DatamapItemFields.Add("min", "0");

        item1.DatamapItemFields.Add("max", "40");

        var item2 = new DatamapItem();

        item2.DatamapItemFields.Add("paramName", "VE8321C");

        item2.DatamapItemFields.Add("min", "0");

        item2.DatamapItemFields.Add("max", "40");

​

        var item3 = new DatamapItem();

        item3.datamapKey.Add("module", 1);

        item3.datamapKey.Add("id", 1391);

        item3.datamapKey1.Add("module", 1);

        item3.datamapKey1.Add("id", 1391);

        item3.DatamapItemFields.Add("paramName", "VE8321C");

        item3.DatamapItemFields.Add("min", "0");

        item3.DatamapItemFields.Add("max", "40");

        var root = new RootObject

        {

            datamapItems = new List<DatamapItem> { item1, item2, item3 }

        };

​

        var settings = new JsonSerializerSettings

        {

            ContractResolver = IgnoreEmptyEnumerablesResolver.Instance,

            Formatting = Formatting.Indented

        };

​

        var json = JsonConvert.SerializeObject(root, settings);

​

        Console.WriteLine(json);

    }

}

​

public class DatamapItem

{

    [JsonExtensionData]

    public Dictionary<string, JToken> DatamapItemFields { get; set; }

    public Dictionary<string, JToken> datamapKey { get; set; }

    public Dictionary<string, JToken> datamapKey1 { get; set; }

    public DatamapItem()

    {

        DatamapItemFields = new Dictionary<string, JToken>();

        datamapKey = new Dictionary<string, JToken>();

        datamapKey1 = new Dictionary<string, JToken>();

    }

}

public class RootObject

{

    public List<DatamapItem> datamapItems { get; set; }

}

​

public class IgnoreEmptyEnumerablesResolver : DefaultContractResolver

{

    public static readonly IgnoreEmptyEnumerablesResolver Instance = new IgnoreEmptyEnumerablesResolver();

​

    protected override JsonProperty CreateProperty(MemberInfo member, MemberSerialization memberSerialization)

    {

        var property = base.CreateProperty(member, memberSerialization);

​

        if (property.PropertyType != typeof(string) &&

            typeof(IEnumerable).IsAssignableFrom(property.PropertyType))

        {

            property.ShouldSerialize = instance =>

            {

                IEnumerable enumerable = null;

​

                // this value could be in a public field or public property

                switch (member.MemberType)

                {

                    case MemberTypes.Property:

                        enumerable = instance

                            .GetType()

                            .GetProperty(member.Name)

                            .GetValue(instance, null) as IEnumerable;

                        break;

                    case MemberTypes.Field:

                        enumerable = instance

                            .GetType()

                            .GetField(member.Name)

                            .GetValue(instance) as IEnumerable;

                        break;

                    default:

                        break;

​

                }

​

                if (enumerable != null)

                {

                    // check to see if there is at least one item in the Enumerable

                    return enumerable.GetEnumerator().MoveNext();

                }

                else

                {

                    // if the list is null, we defer the decision to NullValueHandling

                    return true;

                }

​

            };

        }

​

        return property;

    }

}

​