Fast-endpoints global headers in swagger for all endpoints

Question

I am using fast-endpoints library for building a minimal API. I need to have two generic headers (name, tracking-Id) across all methods of all the resources.

To implement this requirement, I have used a custom implementation of IGlobalPreProcessor which checks if the incoming requests have these headers. It sends out a validation failure message if the headers are not present.

However on the swagger page, I don't see these two headers. I need help to add these two headers on swagger.

I have tried to implement IOperationProcessor, but not sure how to use it with fast-endpoints as builder.services.AddOpenApiDocument() is called inside fast-endpoints extension builder.Services.SwaggerDocument()

Answer 1

you can register an IOperationProcessor like this with FastEndpoints:

builder.Services.SwaggerDocument(o =>
{
    o.DocumentSettings = s => s.OperationProcessors.Add(new AddCustomHeader());
});

and here's an example processor that adds a custom header to the swagger doc globally:

internal sealed class AddCustomHeader : IOperationProcessor
{
    public bool Process(OperationProcessorContext context)
    {
        var hdrParameter = new OpenApiParameter()
        {
            Name = "x-custom",
            Kind = OpenApiParameterKind.Header,
            IsRequired = true,
            Type = JsonObjectType.String,
            Default = "xyz",
            Description = "The description of the field"
        };

        context.OperationDescription.Operation.Parameters.Add(hdrParameter);

        return true;
    }
}