JsonTypeDefinition 1.0.0-alpha001

.NET 6.0 .NET Standard 2.0
This is a prerelease version of JsonTypeDefinition.
dotnet add package JsonTypeDefinition --version 1.0.0-alpha001
NuGet\Install-Package JsonTypeDefinition -Version 1.0.0-alpha001
This command is intended to be used within the Package Manager Console in Visual Studio, as it uses the NuGet module's version of Install-Package.
<PackageReference Include="JsonTypeDefinition" Version="1.0.0-alpha001" />
For projects that support PackageReference, copy this XML node into the project file to reference the package.
paket add JsonTypeDefinition --version 1.0.0-alpha001
#r "nuget: JsonTypeDefinition, 1.0.0-alpha001"
#r directive can be used in F# Interactive and Polyglot Notebooks. Copy this into the interactive tool or source code of the script to reference the package.
// Install JsonTypeDefinition as a Cake Addin
#addin nuget:?package=JsonTypeDefinition&version=1.0.0-alpha001&prerelease

// Install JsonTypeDefinition as a Cake Tool
#tool nuget:?package=JsonTypeDefinition&version=1.0.0-alpha001&prerelease


An RFC 8927 compliant parser for .NET.

Json Type Definitions (JTDs) provide a human-readable, portable type description that can be consumed by any programming language.

A common use-case would be a REST API describing the form in which payloads are expected. It could publicize this form as a Json Type Definition which could subsequently be interpreted by any client independent of their technology stack.



dotnet add package JsonTypeDefinition



The JsonTypeDefinitionParser provides two methods:

var x = JsonTypeDefinitionParser.Parse(typeof(User));
var y = JsonTypeDefinitionParser.Parse<User>();

Both methods will produce the same output. Given the following types:

class User
    public string Name { get; set; }
    public Address Address { get; set; }
    public DateTimeOffset JoinedAt { get; set; }
    public double GPA { get; set; }

class Address 
    public string StreetName { get; set; }
    public int HouseNumber { get; set; }

The parser would produce the following Json Type Definition:

    "properties": {
        "Name": { "type": "string" }
    "optionalProperties": {
        "Address": { "ref": "Address" },
        "JoinedAt": { "type": "timestamp" },
        "GPA": { "type": "float64" }
    "definitions": {
        "Adress": {
            "optionalProperties": {
                "StreetName": { "type": "string" },
                "HouseNumber": { "type": "int32" }

Do note that JsonTypeDefinitionParser.Parse returns a record of type RootSchema and has no reference to Newtonsoft.Json or System.Text.Json. Feel free to use your favorite JSON serializer to get the appropriate JSON representation! Recommended serialization settings:

// Newtonsoft.Json:
var settings = new Newtonsoft.Json.JsonSerializerSettings()
    NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore,
    Converters = new Newtonsoft.Json.JsonConverter[] { new Newtonsoft.Json.Converters.StringEnumConverter() }

// System.Text.Json:
var options = new System.Text.Json.JsonSerializerOptions { IgnoreNullValues = true };
options.Converters.Add(new System.Text.Json.Serialization.JsonStringEnumConverter());



When defining the models it is important to design them around the limitations that come with a portable, consumer agnostic type definition.

Some commonly used .NET types are currently not supported, including System.TimeSpan. Imagine what would happen if you were to create a JTD from a time span object. RFC 8927 does not define a fitting primitive type that could be used (timestamp is more akin to System.DateTimeOffset) as there is no universally agreed upon way to describe durations. 10 minutes could be described as 00:10:00, PT10M (ISO 8601), 3600 (in seconds), etc. There would be no way for consumers of the JTD to know which notation to use. Instead you're encouraged to work around these limitations for example by replacing

public TimeSpan TimeToLive { get; set; }


public double TimeToLiveInSeconds { get; set; }

so that any consumer nows exactly what format you expect.


Future improvements

Contributions are welcome 😃

  • custom handlers for handling otherwise unsupported types
  • generate .NET types from JTDs
Product Compatible and additional computed target framework versions.
.NET net5.0 was computed.  net5.0-windows was computed.  net6.0 is compatible.  net6.0-android was computed.  net6.0-ios was computed.  net6.0-maccatalyst was computed.  net6.0-macos was computed.  net6.0-tvos was computed.  net6.0-windows was computed.  net7.0 was computed.  net7.0-android was computed.  net7.0-ios was computed.  net7.0-maccatalyst was computed.  net7.0-macos was computed.  net7.0-tvos was computed.  net7.0-windows was computed. 
.NET Core netcoreapp2.0 was computed.  netcoreapp2.1 was computed.  netcoreapp2.2 was computed.  netcoreapp3.0 was computed.  netcoreapp3.1 was computed. 
.NET Standard netstandard2.0 is compatible.  netstandard2.1 was computed. 
.NET Framework net461 was computed.  net462 was computed.  net463 was computed.  net47 was computed.  net471 was computed.  net472 was computed.  net48 was computed.  net481 was computed. 
MonoAndroid monoandroid was computed. 
MonoMac monomac was computed. 
MonoTouch monotouch was computed. 
Tizen tizen40 was computed.  tizen60 was computed. 
Xamarin.iOS xamarinios was computed. 
Xamarin.Mac xamarinmac was computed. 
Xamarin.TVOS xamarintvos was computed. 
Xamarin.WatchOS xamarinwatchos was computed. 
Compatible target framework(s)
Additional computed target framework(s)
Learn more about Target Frameworks and .NET Standard.

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Version Downloads Last updated
1.0.0-alpha001 217 2/13/2022