Samples for Newtonsoft migration doc (#1837)

snippets/core/system-text-json/csharp/DateTimeOffsetNullHandlingConverter.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Globalization;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace SystemTextJsonSamples
+{
+    public class DateTimeOffsetNullHandlingConverter : JsonConverter<DateTimeOffset>
+
+    {
+        public override DateTimeOffset Read(
+            ref Utf8JsonReader reader, 
+            Type typeToConvert, 
+            JsonSerializerOptions options)
+        {
+            if (reader.TokenType == JsonTokenType.Null)
+            {
+                return default;
+            }
+            return reader.GetDateTimeOffset();
+        }
+
+        public override void Write(
+            Utf8JsonWriter writer, 
+            DateTimeOffset value, 
+            JsonSerializerOptions options)
+        {
+            writer.WriteStringValue(value);
+        }
+    }
+}

snippets/core/system-text-json/csharp/ConvertInferredTypesToObject.cs → snippets/core/system-text-json/csharp/DeserializeInferredTypesToObject.cs

@@ -3,7 +3,7 @@
 
 namespace SystemTextJsonSamples
 {
-    public class ConvertInferredTypesToObject
+    public class DeserializeInferredTypesToObject
     {
         public static void Run()
         {

snippets/core/system-text-json/csharp/DeserializeNullToNonnullableType.cs

@@ -0,0 +1,47 @@
+using System;
+using System.Collections.Generic;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace SystemTextJsonSamples
+{
+    public class DeserializeNullToNonnullableType
+    {
+        public static void Run()
+        {
+            string jsonString;
+            var wf = WeatherForecastFactories.CreateWeatherForecast();
+
+            var serializeOptions = new JsonSerializerOptions();
+            serializeOptions.WriteIndented = true;
+            serializeOptions.Converters.Add(new DateTimeOffsetNullHandlingConverter());
+            jsonString = JsonSerializer.Serialize(wf, serializeOptions);
+            Console.WriteLine($"JSON with valid Date:\n{jsonString}\n");
+
+            var deserializeOptions = new JsonSerializerOptions();
+            deserializeOptions.Converters.Add(new DateTimeOffsetNullHandlingConverter());
+            wf = JsonSerializer.Deserialize<WeatherForecast>(jsonString, deserializeOptions);
+            wf.DisplayPropertyValues();
+
+            jsonString = @"{""Date"": null,""TemperatureCelsius"": 25,""Summary"":""Hot""}";
+            Console.WriteLine($"JSON with null Date:\n{jsonString}\n");
+
+            // The missing-date JSON deserializes with error if the converter isn't used.
+            try
+            {
+                wf = JsonSerializer.Deserialize<WeatherForecast>(jsonString);
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine($"Exception thrown: {ex.Message}\n");
+            }
+
+            Console.WriteLine("Deserialize with converter");
+            deserializeOptions = new JsonSerializerOptions();
+            deserializeOptions.Converters.Add(new DateTimeOffsetNullHandlingConverter());
+            wf = JsonSerializer.Deserialize<WeatherForecast>(jsonString, deserializeOptions);
+            wf.DisplayPropertyValues();
+        }
+    }
+
+}

snippets/core/system-text-json/csharp/DeserializeRequiredProperty.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Collections.Generic;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace SystemTextJsonSamples
+{
+    public class DeserializeRequiredProperty
+    {
+        public static void Run()
+        {
+            string jsonString;
+            var wf = WeatherForecastFactories.CreateWeatherForecast();
+
+            var serializeOptions = new JsonSerializerOptions();
+            serializeOptions.WriteIndented = true;
+            serializeOptions.Converters.Add(new WeatherForecastRequiredPropertyConverter());
+            jsonString = JsonSerializer.Serialize(wf, serializeOptions);
+            Console.WriteLine($"JSON with Date:\n{jsonString}\n");
+
+            var deserializeOptions = new JsonSerializerOptions();
+            deserializeOptions.Converters.Add(new WeatherForecastRequiredPropertyConverter());
+            wf = JsonSerializer.Deserialize<WeatherForecast>(jsonString, deserializeOptions);
+            wf.DisplayPropertyValues();
+
+            jsonString = @"{""TemperatureCelsius"": 25,""Summary"":""Hot""}";
+            Console.WriteLine($"JSON without Date:\n{jsonString}\n");
+
+            // The missing-date JSON deserializes without error if the converter isn't used.
+            Console.WriteLine("Deserialize without converter");
+            wf = JsonSerializer.Deserialize<WeatherForecast>(jsonString);
+            wf.DisplayPropertyValues();
+
+            Console.WriteLine("Deserialize with converter");
+            try
+            {
+                deserializeOptions = new JsonSerializerOptions();
+                deserializeOptions.Converters.Add(new WeatherForecastRequiredPropertyConverter());
+                wf = JsonSerializer.Deserialize<WeatherForecast>(jsonString, deserializeOptions);
+            }
+            catch (Exception ex)
+            {
+                Console.WriteLine($"Exception thrown: {ex.Message}\n");
+            }
+            // wf object is unchanged if exception is thrown.
+            wf.DisplayPropertyValues();
+        }
+    }
+
+}

snippets/core/system-text-json/csharp/ImmutablePoint.cs

@@ -0,0 +1,19 @@
+namespace SystemTextJsonSamples
+{
+    // <SnippetImmutablePoint>
+    public struct ImmutablePoint
+    {
+        private readonly int _x;
+        private readonly int _y;
+
+        public ImmutablePoint(int x, int y)
+        {
+            _x = x;
+            _y = y;
+        }
+
+        public int X { get { return _x; } }
+        public int Y { get { return _y; } }
+    }
+    // </SnippetImmutablePoint>
+}

snippets/core/system-text-json/csharp/ImmutablePointConverter.cs

@@ -0,0 +1,112 @@
+using System;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace SystemTextJsonSamples
+{
+    public class ImmutablePointConverter : JsonConverter<ImmutablePoint>
+
+    {
+        private const string XName = "X";
+        private const string YName = "Y";
+
+        public override ImmutablePoint Read(
+            ref Utf8JsonReader reader,
+            Type typeToConvert,
+            JsonSerializerOptions options)
+        {
+            if (reader.TokenType != JsonTokenType.StartObject)
+            {
+                throw new JsonException();
+            };
+
+            int x = default;
+            bool xSet = false;
+
+            int y = default;
+            bool ySet = false;
+
+            // Get the first property.
+            reader.Read();
+            if (reader.TokenType != JsonTokenType.PropertyName)
+            {
+                throw new JsonException();
+            }
+
+            string propertyName = reader.GetString();
+            if (propertyName == XName)
+            {
+                x = ReadProperty(ref reader, options);
+                xSet = true;
+            }
+            else if (propertyName == YName)
+            {
+                y = ReadProperty(ref reader, options);
+                ySet = true;
+            }
+            else
+            {
+                throw new JsonException();
+            }
+
+            // Get the second property.
+            reader.Read();
+            if (reader.TokenType != JsonTokenType.PropertyName)
+            {
+                throw new JsonException();
+            }
+
+            propertyName = reader.GetString();
+            if (propertyName == XName)
+            {
+                x = ReadProperty(ref reader, options);
+                xSet = true;
+            }
+            else if (propertyName == YName)
+            {
+                y = ReadProperty(ref reader, options);
+                ySet = true;
+            }
+            else
+            {
+                throw new JsonException();
+            }
+
+            if (!xSet || !ySet)
+            {
+                throw new JsonException();
+            }
+
+            reader.Read();
+
+            if (reader.TokenType != JsonTokenType.EndObject)
+            {
+                throw new JsonException();
+            }
+
+            return new ImmutablePoint(x, y);
+        }
+
+        public int ReadProperty(ref Utf8JsonReader reader, JsonSerializerOptions options)
+        {
+            if (options?.GetConverter(typeof(int)) is JsonConverter<int> intConverter)
+            {
+                reader.Read();
+                return intConverter.Read(ref reader, typeof(int), options);
+            }
+            else
+            {
+                throw new JsonException();
+            }
+        }
+
+        public override void Write(
+            Utf8JsonWriter writer,
+            ImmutablePoint value,
+            JsonSerializerOptions options)
+        {
+            // Don't pass in options when recursively calling Serialize.
+            JsonSerializer.Serialize(writer, value);
+        }
+    }
+}

snippets/core/system-text-json/csharp/LongToStringConverter.cs

@@ -0,0 +1,31 @@
+using System;
+using System.Buffers;
+using System.Buffers.Text;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace SystemTextJsonSamples
+{
+    public class LongToStringConverter : JsonConverter<long>
+    {
+        public override long Read(ref Utf8JsonReader reader, Type type, JsonSerializerOptions options)
+        {
+            if (reader.TokenType == JsonTokenType.String)
+            {
+                ReadOnlySpan<byte> span = reader.HasValueSequence ? reader.ValueSequence.ToArray() : reader.ValueSpan;
+                if (Utf8Parser.TryParse(span, out long number, out int bytesConsumed) && span.Length == bytesConsumed)
+                    return number;
+
+                if (Int64.TryParse(reader.GetString(), out number))
+                    return number;
+            }
+
+            return reader.GetInt64();
+        }
+
+        public override void Write(Utf8JsonWriter writer, long value, JsonSerializerOptions options)
+        {
+            writer.WriteStringValue(value.ToString());
+        }
+    }
+}

snippets/core/system-text-json/csharp/Program.cs

@@ -71,13 +71,31 @@ static async Task Main(string[] args)
             RegisterConverterWithAttributeOnType.Run();
 
             Console.WriteLine("\n============================= Custom converter Dictionary with TKey = Enum\n");
-            ConvertDictionaryTkeyEnumTValue.Run();
+            RoundtripDictionaryTkeyEnumTValue.Run();
 
             Console.WriteLine("\n============================= Custom converter Polymorphic\n");
-            ConvertPolymorphic.Run();
+            RoundtripPolymorphic.Run();
 
             Console.WriteLine("\n============================= Custom converter inferred types to Object\n");
-            ConvertInferredTypesToObject.Run();
+            DeserializeInferredTypesToObject.Run();
+
+            Console.WriteLine("\n============================= Custom converter long to string\n");
+            RoundtripLongToString.Run();
+
+            Console.WriteLine("\n============================= Callbacks\n");
+            RoundtripCallbacks.Run();
+
+            Console.WriteLine("\n============================= Required property\n");
+            DeserializeRequiredProperty.Run();
+
+            Console.WriteLine("\n============================= Null value to nonnullable type\n");
+            DeserializeNullToNonnullableType.Run();
+
+            Console.WriteLine("\n============================= Immutable struct\n");
+            RoundtripImmutableStruct.Run();
+
+            Console.WriteLine("\n============================= Runtime property exclusion\n");
+            SerializeRuntimePropertyExclusion.Run();
 
             Console.WriteLine("\n============================= JsonDocument data access\n");
             JsonDocumentDataAccess.Run();

snippets/core/system-text-json/csharp/RoundtripCallbacks.cs

@@ -0,0 +1,36 @@
+using System;
+using System.Collections.Generic;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace SystemTextJsonSamples
+{
+    public class RoundtripCallbacks
+    {
+        public static void Run()
+        {
+            string jsonString;
+            var wf = WeatherForecastFactories.CreateWeatherForecast();
+            wf.DisplayPropertyValues();
+
+            // <SnippetSerialize>
+            var serializeOptions = new JsonSerializerOptions();
+            serializeOptions.Converters.Add(new WeatherForecastCallbacksConverter());
+            serializeOptions.WriteIndented = true;
+            jsonString = JsonSerializer.Serialize(wf, serializeOptions);
+            // </SnippetSerialize>
+
+            Console.WriteLine($"JSON output:\n{jsonString}\n");
+            //jsonString = @"{""Date"": null,""TemperatureCelsius"": 25,""Summary"":""Hot""}";
+
+            // <SnippetDeserialize>
+            var deserializeOptions = new JsonSerializerOptions();
+            deserializeOptions.Converters.Add(new WeatherForecastCallbacksConverter());
+            wf = JsonSerializer.Deserialize<WeatherForecast>(jsonString, deserializeOptions);
+            // <SnippetDeserialize>
+
+            wf.DisplayPropertyValues();
+        }
+    }
+
+}

snippets/core/system-text-json/csharp/ConvertDictionaryTkeyEnumTValue.cs → snippets/core/system-text-json/csharp/RoundtripDictionaryTkeyEnumTValue.cs

@@ -3,7 +3,7 @@
 
 namespace SystemTextJsonSamples
 {
-    public class ConvertDictionaryTkeyEnumTValue
+    public class RoundtripDictionaryTkeyEnumTValue
     {
         public static void Run()
         {