Use AsyncAPI extensions

AsyncAPI defines x- extension fields for application-specific data. Use these directly with the library; ordinary extension values do not require a custom parser. The model stores them in an element's Extensions dictionary, keyed by the full extension name, and the reader preserves values as AsyncApiAny by default.

Write an extension

Assign an AsyncApiAny value to the document or another extensible element. AsyncApiAny supports scalar, array, and object values:

using ByteBard.AsyncAPI.Models;

var document = new AsyncApiDocument();
document.Extensions["x-enabled"] = new AsyncApiAny(true);
document.Extensions["x-retries"] = new AsyncApiAny(3);
document.Extensions["x-ratio"] = new AsyncApiAny(2.2m);
document.Extensions["x-labels"] = new AsyncApiAny(new[] { "blue", "green" });
document.Extensions["x-metadata"] = new AsyncApiAny(new { test = 123 });

The extension name must include its x- prefix. Extensions can be set on any model element that exposes an Extensions dictionary.

Read an extension

Without a custom parser, use the extension as an AsyncApiAny and convert it to the expected value type:

var document = new AsyncApiStringReader().Read(input, out var diagnostics);
if (document.Extensions.TryGetValue("x-retries", out var extension) &&
    extension is AsyncApiAny any && any.TryGetValue<int>(out var retries))
{
    Console.WriteLine(retries);
}

The value stays generic; use the AsyncApiAny conversion methods appropriate to its shape. For custom parsing or conversion during reading, see custom extension parsers. The default validation rules check extension naming conventions; see custom validation rules if your validation policy needs adjustment.