Native AOT Support

FluentHttpClient provides a set of AOT-friendly JSON extensions that work with System.Text.Json source generation. These overloads avoid reflection-based serialization and deserialization so you can safely trim and compile your applications ahead of time. The JsonTypeInfo<T> overloads are slightly faster and more explicit, while the JsonSerializerContext overloads allow passing a shared context instance.

XML AOT Support

The XML reflection-based serialization and deserialization helpers provided in FluentHttpClient are not AOT-compatible and should only be used in JIT-compiled applications.

Requirements

• .NET 7.0 or later.
• System.Text.Json source generation (JsonSerializerContext and JsonTypeInfo<T>).
• Generated context that includes metadata for the types you serialize/deserialize.

Example Models

The examples in the following section use this model.

public sealed class SampleModel
{
    public int Id { get; set; }
    public string? Name { get; set; }
}

// Generate AOT metadata for SampleModel
[JsonSerializable(typeof(SampleModel))]
public partial class SampleModelJsonContext : JsonSerializerContext
{
}

Add JSON Content

The AOT-safe JSON content extensions use JsonTypeInfo<T> or JsonSerializerContext.

var model = new SampleModel { Id = 42, Name = "Grant" };

// using JsonTypeInfo<T>
var builder = client
    .UsingBase()
    .WithRoute("api/sample")
    .WithJsonContent(model, SampleModelJsonContext.Default.SampleModel);

// using JsonSerializerContext
var builder = client
    .UsingBase()
    .WithRoute("api/sample")
    .WithJsonContent(model, SampleModelJsonContext.Default);

Available Overloads

• WithJsonContent<T>(T, JsonTypeInfo<T>)
• WithJsonContent<T>(T, JsonTypeInfo<T>, string)
• WithJsonContent<T>(T, JsonTypeInfo<T>, MediaTypeHeaderValue)
• WithJsonContent<T>(T, JsonSerializerContext)
• WithJsonContent<T>(T, JsonSerializerContext, string)
• WithJsonContent<T>(T, JsonSerializerContext, MediaTypeHeaderValue)

Deserialize Typed JSON

The AOT-safe deserialization extensions use JsonTypeInfo<T> or JsonSerializerContext. All extension methods are applicable to HttpResponseMessage and Task<HttpResponseMessage>.

// using JsonTypeInfo<T>
var model = await response.ReadJsonAsync(
    SampleModelJsonContext.Default.SampleModel,
    cancellationToken);

// using a JsonSerializerContext
var model = await response.ReadJsonAsync<SampleModel>(
    SampleModelJsonContext.Default,
    cancellationToken);

Available Overloads

• ReadJsonAsync<T>(JsonTypeInfo<T>, CancellationToken)
• ReadJsonAsync<T>(JsonSerializerContext, CancellationToken)

tip

If the response content is null, empty, or whitespace, these overloads return default(T) (typically null for reference types), matching the behavior of the reflection-based overloads.

Behavior Notes

All methods:

• Use JsonTypeInfo<T> or JsonSerializerContext.
• Do not require dynamic code generation.
• Return default(T) when the HTTP content is null, empty, or whitespace.
• When using JsonSerializerContext overloads, the context must include metadata for the generic type T. If it does not, an InvalidOperationException is thrown.
• The AOT-safe overloads do not use JsonSerializerOptions and cannot honor custom converters unless they are part of the source-generated context.

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Quick Reference

Method	Description
WithJsonContent<T>(T, JsonTypeInfo<T>)	Serializes a value to JSON using source-generated type metadata and sets it as request content with the default JSON media type.
WithJsonContent<T>(T, JsonTypeInfo<T>, string)	Serializes a value using generated type metadata and applies the specified media type.
WithJsonContent<T>(T, JsonTypeInfo<T>, MediaTypeHeaderValue)	Serializes a value using generated type metadata and applies a fully configured content-type header.
WithJsonContent<T>(T, JsonSerializerContext)	Serializes a value using a serializer context (extracting its type metadata) and sets the default JSON media type.
WithJsonContent<T>(T, JsonSerializerContext, string)	Serializes a value using a serializer context and applies the specified media type.
WithJsonContent<T>(T, JsonSerializerContext, MediaTypeHeaderValue)	Serializes a value using a serializer context and applies a fully configured content-type header.
ReadJsonAsync<T>(JsonTypeInfo<T>, CancellationToken)	Deserializes JSON from an HTTP response using generated type metadata, and returns `default(T) when content is empty or null.
ReadJsonAsync<T>(JsonSerializerContext, CancellationToken)	Deserializes JSON using a serializer context (extracting its type metadata), and returns `default(T) when content is empty or null.