[Fork] [Fork] [Fork] https://stackoverflow.com/questions/56835040/net-core-3-0-jsonserializer-populate-existing-object | C# Online Compiler

[Fork] [Fork] [Fork] https://stackoverflow.com/questions/56835040/net-core-3-0-jsonserializer-populate-existing-object by dbc_MinLength

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.Serialization.Formatters;
using System.IO;
using System.Data;
using System.ComponentModel.DataAnnotations;
using System.Globalization;
using System.Reflection;
using System.Collections.ObjectModel;

using System.Text.Json;
using System.Text.Json.Serialization;

using NUnit.Framework; // Throws NUnit.Framework.AssertionException

//https://stackoverflow.com/questions/56835040/net-core-3-0-jsonserializer-populate-existing-object

	// MyClass and JsonPopulator copied from this answer https://stackoverflow.com/a/56914059/3744182
	// To https://stackoverflow.com/questions/56835040/net-core-3-0-jsonserializer-populate-existing-object
	// By https://stackoverflow.com/users/403671/simon-mourier

	public class MyClass
	{
		public string Title { get; set; }
		public string Head { get; set; }
		public string Link { get; set; }
	}

	public class JsonPopulator
	{
		public void PopulateObject(object obj, string jsonString, JsonSerializerOptions options = null) => PopulateObject(obj, jsonString != null ? Encoding.UTF8.GetBytes(jsonString) : null, options);
		public virtual void PopulateObject(object obj, ReadOnlySpan<byte> jsonData, JsonSerializerOptions options = null)
		{
			options ??= new JsonSerializerOptions();
			var state = new JsonReaderState(new JsonReaderOptions { AllowTrailingCommas = options.AllowTrailingCommas, CommentHandling = options.ReadCommentHandling, MaxDepth = options.MaxDepth });
			var reader = new Utf8JsonReader(jsonData, isFinalBlock: true, state);
			new Worker(this, reader, obj, options);
		}

		protected virtual PropertyInfo GetProperty(ref Utf8JsonReader reader, JsonSerializerOptions options, object obj, string propertyName)
		{
			if (obj == null)
				throw new ArgumentNullException(nameof(obj));

			if (propertyName == null)
				throw new ArgumentNullException(nameof(propertyName));

			var prop = obj.GetType().GetProperty(propertyName);
			return prop;
		}

		protected virtual bool SetPropertyValue(ref Utf8JsonReader reader, JsonSerializerOptions options, object obj, string propertyName)
		{
			if (obj == null)
				throw new ArgumentNullException(nameof(obj));

			if (propertyName == null)
				throw new ArgumentNullException(nameof(propertyName));

			var prop = GetProperty(ref reader, options, obj, propertyName);
			if (prop == null)
				return false;

			if (!TryReadPropertyValue(ref reader, options, prop.PropertyType, out var value))
				return false;

			prop.SetValue(obj, value);
			return true;
		}

		protected virtual bool TryReadPropertyValue(ref Utf8JsonReader reader, JsonSerializerOptions options, Type propertyType, out object value)
		{
			if (propertyType == null)
				throw new ArgumentNullException(nameof(reader));

			if (reader.TokenType == JsonTokenType.Null)
			{
				value = null;
				return !propertyType.IsValueType || Nullable.GetUnderlyingType(propertyType) != null;
			}

			if (propertyType == typeof(object)) { value = ReadValue(ref reader); return true; }
			if (propertyType == typeof(string))
			if (propertyType == typeof(string)) // Fixed -dbc
			{ 
				value = JsonSerializer.Deserialize<JsonElement>(ref reader, options).GetString(); 
				return true; 
			}
			if (propertyType == typeof(int) && reader.TryGetInt32(out var i32)) { value = i32; return true; }
			if (propertyType == typeof(long) && reader.TryGetInt64(out var i64)) { value = i64; return true; }
			if (propertyType == typeof(DateTime) && reader.TryGetDateTime(out var dt)) { value = dt; return true; }
			if (propertyType == typeof(DateTimeOffset) && reader.TryGetDateTimeOffset(out var dto)) { value = dto; return true; }
			if (propertyType == typeof(Guid) && reader.TryGetGuid(out var guid)) { value = guid; return true; }
			if (propertyType == typeof(decimal) && reader.TryGetDecimal(out var dec)) { value = dec; return true; }
			if (propertyType == typeof(double) && reader.TryGetDouble(out var dbl)) { value = dbl; return true; }
			if (propertyType == typeof(float) && reader.TryGetSingle(out var sgl)) { value = sgl; return true; }
			if (propertyType == typeof(uint) && reader.TryGetUInt32(out var ui32)) { value = ui32; return true; }
			if (propertyType == typeof(ulong) && reader.TryGetUInt64(out var ui64)) { value = ui64; return true; }
			if (propertyType == typeof(byte[]) && reader.TryGetBytesFromBase64(out var bytes)) { value = bytes; return true; }

			if (propertyType == typeof(bool))
			{
				if (reader.TokenType == JsonTokenType.False || reader.TokenType == JsonTokenType.True)
				{
					value = reader.GetBoolean();
					return true;
				}
			}

			// fallback here
			return TryConvertValue(ref reader, propertyType, out value);
		}

		protected virtual object ReadValue(ref Utf8JsonReader reader)
		{
			switch (reader.TokenType)
			{
				case JsonTokenType.False: return false;
				case JsonTokenType.True: return true;
				case JsonTokenType.Null: return null;
				case JsonTokenType.String: return reader.GetString();

				case JsonTokenType.Number: // is there a better way?
					if (reader.TryGetInt32(out var i32))
						return i32;

					if (reader.TryGetInt64(out var i64))
						return i64;

					if (reader.TryGetUInt64(out var ui64)) // uint is already handled by i64
						return ui64;

					if (reader.TryGetSingle(out var sgl))
						return sgl;

					if (reader.TryGetDouble(out var dbl))
						return dbl;

					if (reader.TryGetDecimal(out var dec))
						return dec;

					break;
			}
			throw new NotSupportedException();
		}

		// we're here when json types & property types don't match exactly
		protected virtual bool TryConvertValue(ref Utf8JsonReader reader, Type propertyType, out object value)
		{
			if (propertyType == null)
				throw new ArgumentNullException(nameof(reader));

			if (propertyType == typeof(bool))
			{
				if (reader.TryGetInt64(out var i64)) // one size fits all
				{
					value = i64 != 0;
					return true;
				}
			}

			// TODO: add other conversions

			value = null;
			return false;
		}

		protected virtual object CreateInstance(ref Utf8JsonReader reader, Type propertyType)
		{
			if (propertyType.GetConstructor(Type.EmptyTypes) == null)
				return null;

			// TODO: handle custom instance creation
			try
			{
				return Activator.CreateInstance(propertyType);
			}
			catch
			{
				// swallow
				return null;
			}
		}

		private class Worker
		{
			private readonly Stack<WorkerProperty> _properties = new Stack<WorkerProperty>();
			private readonly Stack<object> _objects = new Stack<object>();

			public Worker(JsonPopulator populator, Utf8JsonReader reader, object obj, JsonSerializerOptions options)
			{
				_objects.Push(obj);
				WorkerProperty prop;
				WorkerProperty peek;
				while (reader.Read())
				{
					switch (reader.TokenType)
					{
						case JsonTokenType.PropertyName:
							prop = new WorkerProperty();
							prop.PropertyName = Encoding.UTF8.GetString(reader.ValueSpan);
							_properties.Push(prop);
							break;

						case JsonTokenType.StartObject:
						case JsonTokenType.StartArray:
							if (_properties.Count > 0)
							{
								object child = null;
								var parent = _objects.Peek();
								PropertyInfo pi = null;
								if (parent != null)
								{
									pi = populator.GetProperty(ref reader, options, parent, _properties.Peek().PropertyName);
									if (pi != null)
									{
										child = pi.GetValue(parent); // mimic ObjectCreationHandling.Auto
										if (child == null && pi.CanWrite)
										{
											if (reader.TokenType == JsonTokenType.StartArray)
											{
												if (!typeof(IList).IsAssignableFrom(pi.PropertyType))
													break;  // don't create if we can't handle it
											}

											if (reader.TokenType == JsonTokenType.StartArray && pi.PropertyType.IsArray)
											{
												child = Activator.CreateInstance(typeof(List<>).MakeGenericType(pi.PropertyType.GetElementType())); // we can't add to arrays...
											}
											else
											{
												child = populator.CreateInstance(ref reader, pi.PropertyType);
												if (child != null)
												{
													pi.SetValue(parent, child);
												}
											}
										}
									}
								}

								if (reader.TokenType == JsonTokenType.StartObject)
								{
									_objects.Push(child);
								}
								else if (child != null) // StartArray
								{
									peek = _properties.Peek();
									peek.IsArray = pi.PropertyType.IsArray;
									peek.List = (IList)child;
									peek.ListPropertyType = GetListElementType(child.GetType());
									peek.ArrayPropertyInfo = pi;
								}
							}
							break;

						case JsonTokenType.EndObject:
							_objects.Pop();
							if (_properties.Count > 0)
							{
								_properties.Pop();
							}
							break;

						case JsonTokenType.EndArray:
							if (_properties.Count > 0)
							{
								prop = _properties.Pop();
								if (prop.IsArray)
								{
									var array = Array.CreateInstance(GetListElementType(prop.ArrayPropertyInfo.PropertyType), prop.List.Count); // array is finished, convert list into a real array
									prop.List.CopyTo(array, 0);
									prop.ArrayPropertyInfo.SetValue(_objects.Peek(), array);
								}
							}
							break;

						case JsonTokenType.False:
						case JsonTokenType.Null:
						case JsonTokenType.Number:
						case JsonTokenType.String:
						case JsonTokenType.True:
							peek = _properties.Peek();
							if (peek.List != null)
							{
								if (populator.TryReadPropertyValue(ref reader, options, peek.ListPropertyType, out var item))
								{
									peek.List.Add(item);
								}
								break;
							}

							prop = _properties.Pop();
							var current = _objects.Peek();
							if (current != null)
							{
								populator.SetPropertyValue(ref reader, options, current, prop.PropertyName);
							}
							break;
					}
				}
			}

			private static Type GetListElementType(Type type)
			{
				if (type.IsArray)
					return type.GetElementType();

				foreach (Type iface in type.GetInterfaces())
				{
					if (!iface.IsGenericType) continue;
					if (iface.GetGenericTypeDefinition() == typeof(IDictionary<,>)) return iface.GetGenericArguments()[1];
					if (iface.GetGenericTypeDefinition() == typeof(IList<>)) return iface.GetGenericArguments()[0];
					if (iface.GetGenericTypeDefinition() == typeof(ICollection<>)) return iface.GetGenericArguments()[0];
					if (iface.GetGenericTypeDefinition() == typeof(IEnumerable<>)) return iface.GetGenericArguments()[0];
				}
				return typeof(object);
			}
		}

		private class WorkerProperty
		{
			public string PropertyName;
			public IList List;
			public Type ListPropertyType;
			public bool IsArray;
			public PropertyInfo ArrayPropertyInfo;

			public override string ToString() => PropertyName;
		}
	}

    class TestClass
    {
        public static void Test()
		{
			TestStandalonePopulate();
		}
		
		static void AssertEqual(MyClass class1, MyClass class2)
		{
			if (class1 == class2)
				return;
			Assert.IsTrue(class1 != null && class2 != null);
			Assert.AreEqual(class1.Title, class2.Title);
			Assert.AreEqual(class1.Head, class2.Head);
			Assert.AreEqual(class1.Link, class2.Link);
		}
		
		static void TestStandalonePopulate()
        {
			var myClass = new MyClass 
			{
				Title = "my title",
				Head = "my head",
				Link = "my link",
			};
			
			var json = JsonSerializer.Serialize(myClass);
			
			Console.WriteLine(json);
						
			var class2 = new MyClass();
			
			new JsonPopulator().PopulateObject(class2, json, null);
			
			AssertEqual(myClass, class2);
		}
	}

	public class Program
	{
		public static void Main()
		{
			Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , GetNetCoreVersion());
			Console.WriteLine("System.Text.Json version: " + typeof(JsonSerializer).Assembly.FullName);
			Console.WriteLine();

			try
			{
				TestClass.Test();
			}
			catch (Exception ex)
			{
				Console.WriteLine("Failed with unhandled exception: ");
				Console.WriteLine(ex);
				throw;
			}
		}
		
		public static string GetNetCoreVersion()
		{
			//https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be
			//
			var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;
			var assemblyPath = assembly.CodeBase.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);
			int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");
			if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)
				return assemblyPath[netCoreAppIndex + 1];
			return null;
		}
	}

​x
 
using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.Serialization.Formatters;
using System.IO;
using System.Data;
using System.ComponentModel.DataAnnotations;
using System.Globalization;
using System.Reflection;
using System.Collections.ObjectModel;
​
using System.Text.Json;
using System.Text.Json.Serialization;
​
using NUnit.Framework; // Throws NUnit.Framework.AssertionException
​
//https://stackoverflow.com/questions/56835040/net-core-3-0-jsonserializer-populate-existing-object
​
    // MyClass and JsonPopulator copied from this answer https://stackoverflow.com/a/56914059/3744182
    // To https://stackoverflow.com/questions/56835040/net-core-3-0-jsonserializer-populate-existing-object
    // By https://stackoverflow.com/users/403671/simon-mourier
​
    public class MyClass
    {
        public string Title { get; set; }
        public string Head { get; set; }
        public string Link { get; set; }
    }
​
    public class JsonPopulator
    {
        public void PopulateObject(object obj, string jsonString, JsonSerializerOptions options = null) => PopulateObject(obj, jsonString != null ? Encoding.UTF8.GetBytes(jsonString) : null, options);
        public virtual void PopulateObject(object obj, ReadOnlySpan<byte> jsonData, JsonSerializerOptions options = null)
        {
            options ??= new JsonSerializerOptions();
            var state = new JsonReaderState(new JsonReaderOptions { AllowTrailingCommas = options.AllowTrailingCommas, CommentHandling = options.ReadCommentHandling, MaxDepth = options.MaxDepth });
            var reader = new Utf8JsonReader(jsonData, isFinalBlock: true, state);
            new Worker(this, reader, obj, options);
        }
​
        protected virtual PropertyInfo GetProperty(ref Utf8JsonReader reader, JsonSerializerOptions options, object obj, string propertyName)
        {
            if (obj == null)
                throw new ArgumentNullException(nameof(obj));
​
            if (propertyName == null)
                throw new ArgumentNullException(nameof(propertyName));
​
            var prop = obj.GetType().GetProperty(propertyName);
            return prop;
        }
​
        protected virtual bool SetPropertyValue(ref Utf8JsonReader reader, JsonSerializerOptions options, object obj, string propertyName)
        {
            if (obj == null)
                throw new ArgumentNullException(nameof(obj));
​
            if (propertyName == null)
                throw new ArgumentNullException(nameof(propertyName));
​
            var prop = GetProperty(ref reader, options, obj, propertyName);
            if (prop == null)
                return false;
​
            if (!TryReadPropertyValue(ref reader, options, prop.PropertyType, out var value))
                return false;
​
            prop.SetValue(obj, value);
            return true;
        }
​
        protected virtual bool TryReadPropertyValue(ref Utf8JsonReader reader, JsonSerializerOptions options, Type propertyType, out object value)
        {
            if (propertyType == null)
                throw new ArgumentNullException(nameof(reader));
​
            if (reader.TokenType == JsonTokenType.Null)
            {
                value = null;
                return !propertyType.IsValueType || Nullable.GetUnderlyingType(propertyType) != null;
            }
​
            if (propertyType == typeof(object)) { value = ReadValue(ref reader); return true; }
            if (propertyType == typeof(string))
            if (propertyType == typeof(string)) // Fixed -dbc
            { 
                value = JsonSerializer.Deserialize<JsonElement>(ref reader, options).GetString(); 
                return true; 
            }
            if (propertyType == typeof(int) && reader.TryGetInt32(out var i32)) { value = i32; return true; }
            if (propertyType == typeof(long) && reader.TryGetInt64(out var i64)) { value = i64; return true; }
            if (propertyType == typeof(DateTime) && reader.TryGetDateTime(out var dt)) { value = dt; return true; }
            if (propertyType == typeof(DateTimeOffset) && reader.TryGetDateTimeOffset(out var dto)) { value = dto; return true; }
            if (propertyType == typeof(Guid) && reader.TryGetGuid(out var guid)) { value = guid; return true; }
            if (propertyType == typeof(decimal) && reader.TryGetDecimal(out var dec)) { value = dec; return true; }
            if (propertyType == typeof(double) && reader.TryGetDouble(out var dbl)) { value = dbl; return true; }
            if (propertyType == typeof(float) && reader.TryGetSingle(out var sgl)) { value = sgl; return true; }
            if (propertyType == typeof(uint) && reader.TryGetUInt32(out var ui32)) { value = ui32; return true; }
            if (propertyType == typeof(ulong) && reader.TryGetUInt64(out var ui64)) { value = ui64; return true; }
            if (propertyType == typeof(byte[]) && reader.TryGetBytesFromBase64(out var bytes)) { value = bytes; return true; }
​
            if (propertyType == typeof(bool))
            {
                if (reader.TokenType == JsonTokenType.False || reader.TokenType == JsonTokenType.True)
                {
                    value = reader.GetBoolean();
                    return true;
                }
            }
​
            // fallback here
            return TryConvertValue(ref reader, propertyType, out value);
        }
​
        protected virtual object ReadValue(ref Utf8JsonReader reader)
        {
            switch (reader.TokenType)
            {
                case JsonTokenType.False: return false;
                case JsonTokenType.True: return true;
                case JsonTokenType.Null: return null;
                case JsonTokenType.String: return reader.GetString();
​
                case JsonTokenType.Number: // is there a better way?
                    if (reader.TryGetInt32(out var i32))
                        return i32;
​
                    if (reader.TryGetInt64(out var i64))
                        return i64;
​
                    if (reader.TryGetUInt64(out var ui64)) // uint is already handled by i64
                        return ui64;
​
                    if (reader.TryGetSingle(out var sgl))
                        return sgl;
​
                    if (reader.TryGetDouble(out var dbl))
                        return dbl;
​
                    if (reader.TryGetDecimal(out var dec))
                        return dec;
​
                    break;
            }
            throw new NotSupportedException();
        }
​
        // we're here when json types & property types don't match exactly
        protected virtual bool TryConvertValue(ref Utf8JsonReader reader, Type propertyType, out object value)
        {
            if (propertyType == null)
                throw new ArgumentNullException(nameof(reader));
​
            if (propertyType == typeof(bool))
            {
                if (reader.TryGetInt64(out var i64)) // one size fits all
                {
                    value = i64 != 0;
                    return true;
                }
            }
​
            // TODO: add other conversions
​
            value = null;
            return false;
        }
​
        protected virtual object CreateInstance(ref Utf8JsonReader reader, Type propertyType)
        {
            if (propertyType.GetConstructor(Type.EmptyTypes) == null)
                return null;
​
            // TODO: handle custom instance creation
            try
            {
                return Activator.CreateInstance(propertyType);
            }
            catch
            {
                // swallow
                return null;
            }
        }
​
        private class Worker
        {
            private readonly Stack<WorkerProperty> _properties = new Stack<WorkerProperty>();
            private readonly Stack<object> _objects = new Stack<object>();
​
            public Worker(JsonPopulator populator, Utf8JsonReader reader, object obj, JsonSerializerOptions options)
            {
                _objects.Push(obj);
                WorkerProperty prop;
                WorkerProperty peek;
                while (reader.Read())
                {
                    switch (reader.TokenType)
                    {
                        case JsonTokenType.PropertyName:
                            prop = new WorkerProperty();
                            prop.PropertyName = Encoding.UTF8.GetString(reader.ValueSpan);
                            _properties.Push(prop);
                            break;
​
                        case JsonTokenType.StartObject:
                        case JsonTokenType.StartArray:
                            if (_properties.Count > 0)
                            {
                                object child = null;
                                var parent = _objects.Peek();
                                PropertyInfo pi = null;
                                if (parent != null)
                                {
                                    pi = populator.GetProperty(ref reader, options, parent, _properties.Peek().PropertyName);
                                    if (pi != null)
                                    {
                                        child = pi.GetValue(parent); // mimic ObjectCreationHandling.Auto
                                        if (child == null && pi.CanWrite)
                                        {
                                            if (reader.TokenType == JsonTokenType.StartArray)
                                            {
                                                if (!typeof(IList).IsAssignableFrom(pi.PropertyType))
                                                    break;  // don't create if we can't handle it
                                            }
​
                                            if (reader.TokenType == JsonTokenType.StartArray && pi.PropertyType.IsArray)
                                            {
                                                child = Activator.CreateInstance(typeof(List<>).MakeGenericType(pi.PropertyType.GetElementType())); // we can't add to arrays...
                                            }
                                            else
                                            {
                                                child = populator.CreateInstance(ref reader, pi.PropertyType);
                                                if (child != null)
                                                {
                                                    pi.SetValue(parent, child);
                                                }
                                            }
                                        }
                                    }
                                }
​
                                if (reader.TokenType == JsonTokenType.StartObject)
                                {
                                    _objects.Push(child);
                                }
                                else if (child != null) // StartArray
                                {
                                    peek = _properties.Peek();
                                    peek.IsArray = pi.PropertyType.IsArray;
                                    peek.List = (IList)child;
                                    peek.ListPropertyType = GetListElementType(child.GetType());
                                    peek.ArrayPropertyInfo = pi;
                                }
                            }
                            break;
​
                        case JsonTokenType.EndObject:
                            _objects.Pop();
                            if (_properties.Count > 0)
                            {
                                _properties.Pop();
                            }
                            break;
​
                        case JsonTokenType.EndArray:
                            if (_properties.Count > 0)
                            {
                                prop = _properties.Pop();
                                if (prop.IsArray)
                                {
                                    var array = Array.CreateInstance(GetListElementType(prop.ArrayPropertyInfo.PropertyType), prop.List.Count); // array is finished, convert list into a real array
                                    prop.List.CopyTo(array, 0);
                                    prop.ArrayPropertyInfo.SetValue(_objects.Peek(), array);
                                }
                            }
                            break;
​
                        case JsonTokenType.False:
                        case JsonTokenType.Null:
                        case JsonTokenType.Number:
                        case JsonTokenType.String:
                        case JsonTokenType.True:
                            peek = _properties.Peek();
                            if (peek.List != null)
                            {
                                if (populator.TryReadPropertyValue(ref reader, options, peek.ListPropertyType, out var item))
                                {
                                    peek.List.Add(item);
                                }
                                break;
                            }
​
                            prop = _properties.Pop();
                            var current = _objects.Peek();
                            if (current != null)
                            {
                                populator.SetPropertyValue(ref reader, options, current, prop.PropertyName);
                            }
                            break;
                    }
                }
            }
​
            private static Type GetListElementType(Type type)
            {
                if (type.IsArray)
                    return type.GetElementType();
​
                foreach (Type iface in type.GetInterfaces())
                {
                    if (!iface.IsGenericType) continue;
                    if (iface.GetGenericTypeDefinition() == typeof(IDictionary<,>)) return iface.GetGenericArguments()[1];
                    if (iface.GetGenericTypeDefinition() == typeof(IList<>)) return iface.GetGenericArguments()[0];
                    if (iface.GetGenericTypeDefinition() == typeof(ICollection<>)) return iface.GetGenericArguments()[0];
                    if (iface.GetGenericTypeDefinition() == typeof(IEnumerable<>)) return iface.GetGenericArguments()[0];
                }
                return typeof(object);
            }
        }
​
        private class WorkerProperty
        {
            public string PropertyName;
            public IList List;
            public Type ListPropertyType;
            public bool IsArray;
            public PropertyInfo ArrayPropertyInfo;
​
            public override string ToString() => PropertyName;
        }
    }
​
    class TestClass
    {
        public static void Test()
        {
            TestStandalonePopulate();
        }
        
        static void AssertEqual(MyClass class1, MyClass class2)
        {
            if (class1 == class2)
                return;
            Assert.IsTrue(class1 != null && class2 != null);
            Assert.AreEqual(class1.Title, class2.Title);
            Assert.AreEqual(class1.Head, class2.Head);
            Assert.AreEqual(class1.Link, class2.Link);
        }
        
        static void TestStandalonePopulate()
        {
            var myClass = new MyClass 
            {
                Title = "my title",
                Head = "my head",
                Link = "my link",
            };
            
            var json = JsonSerializer.Serialize(myClass);
            
            Console.WriteLine(json);
                        
            var class2 = new MyClass();
            
            new JsonPopulator().PopulateObject(class2, json, null);
            
            AssertEqual(myClass, class2);
        }
    }
​
    public class Program
    {
        public static void Main()
        {
            Console.WriteLine("Environment version: {0} ({1})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , GetNetCoreVersion());
            Console.WriteLine("System.Text.Json version: " + typeof(JsonSerializer).Assembly.FullName);
            Console.WriteLine();
​
            try
            {
                TestClass.Test();
            }
            catch (Exception ex)
            {
                Console.WriteLine("Failed with unhandled exception: ");
                Console.WriteLine(ex);
                throw;
            }
        }
        
        public static string GetNetCoreVersion()
        {
            //https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be
            //
            var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;
            var assemblyPath = assembly.CodeBase.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);
            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");
            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)
                return assemblyPath[netCoreAppIndex + 1];
            return null;
        }
    }
​

Hello World! Tom Xiong!

Last Run:	8:32:36 am
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