using System;

using System.Reflection;

public class Program

{

    public static void Main()

    {

        var entry = new DataEntries

        {

            User = new DataEntries.UserObjects

            {

                UserId = "42",

                UserId2 = "64",

            },

            Tag = new DataEntries.TagObjects

            {

                id = 42,

                name = "Ford",

                type = 11,

            },

        };

        var value = entry.GetPropValue("Tag.name");

        Console.WriteLine(value);

    }

}

​

public class DataEntries

{

    public class UserObjects

    {

        public string UserId { get; set; }

        public string UserId2 { get; set; }

    }

​

    public class TagObjects

    {

        public int id { get; set; }

        public string name { get; set; }

        public int type { get; set; } 

        public TagObjects Child { get; set; }

    }

    public UserObjects User { get; set; }

    public TagObjects Tag { get; set; }

}

​

public static class ReflectionHelper 

{

    public static dynamic GetPropValue(this object obj, string propName)

    {

        string[] nameParts = propName.Split('.');

        foreach (string part in nameParts)

        {

            if (obj == null) { return null; }

            Type type = obj.GetType();

            PropertyInfo info = type.GetProperty(part);

            if (info == null) { return null; }

            obj = info.GetValue(obj, null);

        }

        return obj;

    }

}