I check a lot of tutorials and everywhere developers describe that if I add CancellationToken to my request then when the request become cancelled then flag IsCancellationRequested should change from fals to true. But be honest it doesn’t work for me when I run it for .NET 7 & 8. Mabye someone tell me what I’m doing wrong becuase maybe I don’t understand something.

Simple example bellow, when I test it via postman or Swagger and cancel it I have never got status 499.

using Microsoft.AspNetCore.Mvc;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

app.MapGet("/long-running-request", async (CancellationToken cancellationToken) =>
    {
        var randomId = Guid.NewGuid();
        var results = new List<string>();

        for (int i = 0; i < 100; i++)
        {
            if (cancellationToken.IsCancellationRequested)
                return Results.StatusCode(499);

            await Task.Delay(1000);
            var result = $"{randomId} - Result {i}";
            Console.WriteLine(result);
            results.Add(result);
        }

        return Results.Ok(results);
    })
    .WithName("GetAllData")
    .WithOpenApi();


app.Run();

I try to figured out how can I cancel my API request and detect it to stop processing my logic in endpoint.