Provides high-performance and low-allocating types that serialize objects to JavaScript Object Notation (JSON) text and deserialize JSON text to objects, with UTF-8 support built-in. Also provides types to read and write JSON text encoded as UTF-8, and to create an in-memory document object model (DOM), that is read-only, for random access of the JSON elements within a structured view of the data.
The System.Text.Json library is built-in as part of the shared framework in .NET Runtime. The package can be installed when you need to use the most recent version in older target frameworks.
Serialization:
using System;
using System.Text.Json;
WeatherForecast forecast = new (DateTimeOffset.Now, 26.6f, "Sunny");
var serialized = JsonSerializer.Serialize(forecast);
Console.WriteLine(serialized);
// {"Date":"2023-08-02T16:01:20.9025406+00:00","TemperatureCelsius":26.6,"Summary":"Sunny"}
var forecastDeserialized = JsonSerializer.Deserialize<WeatherForecast>(serialized);
Console.WriteLine(forecast == forecastDeserialized);
// True
public record WeatherForecast(DateTimeOffset Date, float TemperatureCelsius, string? Summary);
Serialization using the source generator:
using System.Text.Json;
using System.Text.Json.Serialization;
WeatherForecast forecast = new (DateTimeOffset.Now, 26.6f, "Sunny");
var serialized = JsonSerializer.Serialize(forecast, SourceGenerationContext.Default.WeatherForecast);
Console.WriteLine(serialized);
// {"Date":"2023-08-02T16:01:20.9025406+00:00","TemperatureCelsius":26.6,"Summary":"Sunny"}
var forecastDeserialized = JsonSerializer.Deserialize<WeatherForecast>(serialized, SourceGenerationContext.Default.WeatherForecast);
Console.WriteLine(forecast == forecastDeserialized);
// True
public record WeatherForecast(DateTimeOffset Date, float TemperatureCelsius, string? Summary);
[JsonSourceGenerationOptions(WriteIndented = true)]
[JsonSerializable(typeof(WeatherForecast))]
internal partial class SourceGenerationContext : JsonSerializerContext
{
}
Using the JSON DOM:
using System;
using System.Text.Json;
using System.Text.Json.Nodes;
string jsonString =
@"{
""Date"": ""2019-08-01T00:00:00"",
""Temperature"": 25,
""Summary"": ""Hot"",
""DatesAvailable"": [
""2019-08-01T00:00:00"",
""2019-08-02T00:00:00""
],
""TemperatureRanges"": {
""Cold"": {
""High"": 20,
""Low"": -10
},
""Hot"": {
""High"": 60,
""Low"": 20
}
}
}
";
JsonNode forecastNode = JsonNode.Parse(jsonString)!;
// Get value from a JsonNode.
JsonNode temperatureNode = forecastNode["Temperature"]!;
Console.WriteLine($"Type={temperatureNode.GetType()}");
Console.WriteLine($"JSON={temperatureNode.ToJsonString()}");
//output:
//Type = System.Text.Json.Nodes.JsonValue`1[System.Text.Json.JsonElement]
//JSON = 25
// Get a typed value from a JsonNode.
int temperatureInt = (int)forecastNode["Temperature"]!;
Console.WriteLine($"Value={temperatureInt}");
//output:
//Value=25
// Get a typed value from a JsonNode by using GetValue<T>.
temperatureInt = forecastNode["Temperature"]!.GetValue<int>();
Console.WriteLine($"TemperatureInt={temperatureInt}");
//output:
//Value=25
// Get a JSON object from a JsonNode.
JsonNode temperatureRanges = forecastNode["TemperatureRanges"]!;
Console.WriteLine($"Type={temperatureRanges.GetType()}");
Console.WriteLine($"JSON={temperatureRanges.ToJsonString()}");
//output:
//Type = System.Text.Json.Nodes.JsonObject
//JSON = { "Cold":{ "High":20,"Low":-10},"Hot":{ "High":60,"Low":20} }
// Get a JSON array from a JsonNode.
JsonNode datesAvailable = forecastNode["DatesAvailable"]!;
Console.WriteLine($"Type={datesAvailable.GetType()}");
Console.WriteLine($"JSON={datesAvailable.ToJsonString()}");
//output:
//datesAvailable Type = System.Text.Json.Nodes.JsonArray
//datesAvailable JSON =["2019-08-01T00:00:00", "2019-08-02T00:00:00"]
// Get an array element value from a JsonArray.
JsonNode firstDateAvailable = datesAvailable[0]!;
Console.WriteLine($"Type={firstDateAvailable.GetType()}");
Console.WriteLine($"JSON={firstDateAvailable.ToJsonString()}");
//output:
//Type = System.Text.Json.Nodes.JsonValue`1[System.Text.Json.JsonElement]
//JSON = "2019-08-01T00:00:00"
// Get a typed value by chaining references.
int coldHighTemperature = (int)forecastNode["TemperatureRanges"]!["Cold"]!["High"]!;
Console.WriteLine($"TemperatureRanges.Cold.High={coldHighTemperature}");
//output:
//TemperatureRanges.Cold.High = 20
// Parse a JSON array
JsonNode datesNode = JsonNode.Parse(@"[""2019-08-01T00:00:00"",""2019-08-02T00:00:00""]")!;
JsonNode firstDate = datesNode[0]!.GetValue<DateTime>();
Console.WriteLine($"firstDate={ firstDate}");
//output:
//firstDate = "2019-08-01T00:00:00"
Using the low-level JSON reader/writer types
using System;
using System.IO;
using System.Text;
using System.Text.Json;
var writerOptions = new JsonWriterOptions
{
Indented = true
};
using var stream = new MemoryStream();
using var writer = new Utf8JsonWriter(stream, writerOptions);
writer.WriteStartObject();
writer.WriteString("date", DateTimeOffset.Parse("8/2/2023 9:00 AM"));
writer.WriteNumber("temp", 42);
writer.WriteEndObject();
writer.Flush();
var jsonBytes = stream.ToArray();
string json = Encoding.UTF8.GetString(jsonBytes);
Console.WriteLine(json);
// {
// "date": "2023-08-02T09:00:00+00:00"
// "temp": 42
// }
var readerOptions = new JsonReaderOptions
{
AllowTrailingCommas = true,
CommentHandling = JsonCommentHandling.Skip
};
var reader = new Utf8JsonReader(jsonBytes, readerOptions);
while (reader.Read())
{
Console.Write(reader.TokenType);
switch (reader.TokenType)
{
case JsonTokenType.PropertyName:
case JsonTokenType.String:
{
string? text = reader.GetString();
Console.Write(" ");
Console.Write(text);
break;
}
case JsonTokenType.Number:
{
int intValue = reader.GetInt32();
Console.Write(" ");
Console.Write(intValue);
break;
}
// Other token types elided for brevity
}
Console.WriteLine();
}
// StartObject
// PropertyName date
// String 2023-08-02T09:00:00+00:00
// PropertyName temp
// Number 42
// EndObject
The main types provided by this library are:
System.Text.Json.Utf8JsonWriterSystem.Text.Json.Utf8JsonReaderSystem.Text.Json.JsonSerializerSystem.Text.Json.JsonConverterSystem.Text.Json.JsonDocumentSystem.Text.Json.Nodes.JsonNodeSystem.Text.Json.Serialization.Metadata.JsonTypeInfoSystem.Text.Json is released as open source under the MIT license. Bug reports and contributions are welcome at the GitHub repository.