Minimal API and XML formatters - asp.net

Question

Trying out minimal APIs in .NET 6 and can't make it work with XML content type. If I use standard controllers, using .AddXmlSerializerFormatters() extension does the job:
builder.Services.AddControllers().AddXmlSerializerFormatters();
But when I switch from controller to .MapPost(..), I start getting 415 HTTP responses.
app.MapPost("/endpoint", ([FromBody] Request request) => {})
.Accepts<Request>("text/xml");
HTTP response: 415 Microsoft.AspNetCore.Http.BadHttpRequestException: Expected a
supported JSON media type but got "text/xml"
Is there any other way I can declare XML formatters that will work with minimal APIs?

Answer 1

As suggested by the post linked by guru-stron, it's possible to pass XML documents by implementing your own wrapping model that provides a BindAsync method.
internal sealed class XDocumentModel
{
public XDocumentModel(XDocument document) => Document = document;
public XDocument Document { get; init; }
public static async ValueTask<XDocumentModel?> BindAsync(HttpContext context, ParameterInfo parameter)
{
if (!context.Request.HasXmlContentType())
throw new BadHttpRequestException(
message: "Request content type was not a recognized Xml content type.",
StatusCodes.Status415UnsupportedMediaType);
return new XDocumentModel(await XDocument.LoadAsync(context.Request.Body, LoadOptions.None, CancellationToken.None));
}
}
I added a extension method to HttpRequest for convenient Content-Type validation.
internal static class HttpRequestXmlExtensions
{
public static bool HasXmlContentType(this HttpRequest request)
=> request.Headers.TryGetValue("Content-Type", out var contentType)
&& string.Equals(contentType, "application/xml", StringComparison.InvariantCulture);
}
You can then use the model directly as a paramter by your minimal API endpoint.
app.MapGet("/xml-test", (XDocumentModel model) =>
{
// model.Document <- your passed xml Document
return Results.Ok(new { Value = model.Document.ToString() });
})
Some final thoughts: This implementation enables you to pass a generic XML document to the endpoint. However, if you expect a certain document structure, you could implement this by making the XDocumentModel expect a generic type parameter and extracting this type's properties from the XDocument instance.

Answer 2

I did it this way:
app.MapPost("/endpoint", (HttpContext c) =>
{
var reader = new StreamReader(c.Request.Body);
var xml = reader.ReadToEndAsync().Result;
// You can do with your xml string whatever you want
return Results.Ok();
}).Accepts<HttpRequest>("application/xml");