Nerdbank.Json.AspNetCoreMvcFormatter

Nerdbank.Json.AspNetCoreMvcFormatter

ASP.NET Core MVC input and output formatters backed by Nerdbank.Json, enabling AOT-safe, source-generated JSON in MVC and minimal-hosting Web APIs.

Unlike the built-in System.Text.Json formatters, these formatters:

• use an explicitly supplied, source-generated ITypeShapeProvider — no reflection and no runtime type discovery;
• stream request and response bodies incrementally through Nerdbank.Json's PipeReader/PipeWriter APIs;
• are trimming- and NativeAOT-safe.

Usage

using Microsoft.Extensions.DependencyInjection;
using Nerdbank.Json;
using PolyType;

var serializer = new JsonSerializer();

builder.Services
    .AddControllers()
    .AddNerdbankJsonFormatters(serializer, MyWitness.GeneratedTypeShapeProvider);

MyWitness is any type (often a witness) that lists your model types via [GenerateShape] / [GenerateShapeFor<T>]; its generated ITypeShapeProvider describes every type the formatters can read or write.

By default the Nerdbank.Json formatters are inserted before the built-in System.Text.Json formatters (so they win content negotiation for application/json and +json media types) but do not remove them. To fully take over JSON handling:

.AddNerdbankJsonFormatters(serializer, provider, o => o.ReplaceSystemTextJsonFormatters = true);

If the provider has no shape for a model type, the formatters throw a MissingTypeShapeException rather than silently binding null or falling through, so misconfiguration is obvious.