⚠️ THIS LIB IS UNDER MAINTENANCE

DotNet.J2Class

DotNet.J2Class generates plain .NET POCO types at runtime from JSON payloads using Reflection.Emit. It's useful for quickly mapping unknown or evolving JSON schemas into runtime-accessible objects without maintaining static DTOs.

Quick highlights

• Runtime type generation using TypeBuilder/PropertyBuilder and ILGenerator.
• Supports nested objects and arrays (primitive and object arrays are handled).
• Caches generated types by schema signature to avoid re-emitting identical types.

Getting started

Install (NuGet):

Install-Package DotNetJ2Class

Basic usage

using DotNet.J2Class;

string simple = "{'Foo':'bar'}";
var obj = J2Class.CreateObjectFromJson(simple, "MyClass");
dynamic dyn = obj;
Console.WriteLine(dyn.Foo); // -> bar

string complex = "{'Person': {'Name':'Alice','Age':30}, 'Tags': ['x','y']}";
var obj2 = J2Class.CreateObjectFromComplexJson(complex, "RootClass");
dynamic d2 = obj2;
Console.WriteLine(d2.Person.Name); // -> Alice

Commands

dotnet build
dotnet test
dotnet run --project test/ConsoleApp1

Important notes / gotchas

• The project targets net9.0 (see src/DotNet.J2Class/DotNet.J2Class.csproj).
• Parsing: inputs using single quotes are normalized internally, but prefer valid JSON (double quotes) for robustness.
• Arrays: homogeneous primitive arrays are materialized as typed List<T> (e.g. List<string>); mixed or empty arrays fall back to List<object>.
• Exceptions: CreateObjectFromJson wraps failures in InvalidOperationException to surface errors; CreateObjectFromComplexJson preserves thrown exceptions for easier debugging in some paths.
• Caching: generated types are cached by a schema signature — this improves performance but increases runtime memory usage for many distinct schemas.

Testing

• Tests live in test/DotNet.J2Class.Tests and use NUnit. They cover simple, complex, array, concurrency and basic performance scenarios.

Contributing

• PRs welcome. For larger changes open an issue first.
• When changing parsing or type generation, add tests in test/DotNet.J2Class.Tests demonstrating expected behaviors.

License

MIT