Exception handling in .NET 8: IExecptionHandler

adhakshinamoorthy — Sun, 26 Nov 2023 16:07:08 +0000

This is an example of how to handle exception globally by implementing IExceptionHandler in .NET 8 Minimal Api

ApiResponse.cs

record ApiResponse(bool Success, string Message);

AppExceptionHandler.cs

using Microsoft.AspNetCore.Diagnostics;

public class AppExceptionHandler : IExceptionHandler
{
    public async ValueTask<bool> TryHandleAsync(
        HttpContext httpContext,
        Exception exception,
        CancellationToken cancellationToken)
    {
        httpContext.Response.StatusCode = 501;
        httpContext.Response.ContentType = "application/json";
        await httpContext.Response.WriteAsJsonAsync(
            new ApiResponse(false, exception.Message),
            cancellationToken);
        return true;
    }
}

Program.cs

var builder = WebApplication.CreateBuilder(args);

// Adds an AppExceptionHandler to services
builder.Services.AddExceptionHandler<AppExceptionHandler>();

var app = builder.Build();

// Adds an exception handling middleware to the pipeline
app.UseExceptionHandler(_ => { });

app.MapGet("api", () =>
{
    throw new ApplicationException("Something went wrong");
});

app.Run();

Output

Ref: Microsoft

Rate limiting middleware in .NET 8: Fixed Window Limiter

adhakshinamoorthy — Sat, 25 Nov 2023 19:11:24 +0000

This is an example of how to implement rate limiting middleware using fixed window limiter in .NET 8 Minimal Api

Program.cs

using Microsoft.AspNetCore.RateLimiting;

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

// Add rate limiting service and configure the options
builder.Services.AddRateLimiter(options =>
{
    options.AddFixedWindowLimiter("fixed", config =>
    {
        config.Window = TimeSpan.FromSeconds(5);
        config.PermitLimit = 1;

        // Disable Queue
        config.QueueLimit = 0;

        // Enable Queue
        //config.QueueLimit = 1;
        //config.QueueProcessingOrder = QueueProcessingOrder.OldestFirst;
    });
    options.RejectionStatusCode = StatusCodes.Status429TooManyRequests;
});

var app = builder.Build();
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}
app.UseHttpsRedirection();

// Enables rate limiting 
app.UseRateLimiter();

var summaries = new[]
{
    "Freezing", "Bracing", "Chilly", "Cool", "Mild", "Warm", "Balmy", "Hot", "Sweltering", "Scorching"
};

app.MapGet("/limit", () =>
{
    var forecast = Enumerable.Range(1, 5).Select(index =>
        new WeatherForecast
        (
            DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
            Random.Shared.Next(-20, 55),
            summaries[Random.Shared.Next(summaries.Length)]
        ))
        .ToArray();
    return forecast;
})
.RequireRateLimiting("fixed") // Enables rate limiting on this endpoint
.WithName("Limit")
.WithOpenApi();

app.MapGet("/unlimit", () =>
{
    var forecast = Enumerable.Range(1, 5).Select(index =>
        new WeatherForecast
        (
            DateOnly.FromDateTime(DateTime.Now.AddDays(index)),
            Random.Shared.Next(-20, 55),
            summaries[Random.Shared.Next(summaries.Length)]
        ))
        .ToArray();
    return forecast;
})
.DisableRateLimiting() // Disables rate limiting on this endpoint
.WithName("UnLimit")
.WithOpenApi();

app.Run();

internal record WeatherForecast(DateOnly Date, int TemperatureC, string? Summary)
{
    public int TemperatureF => 32 + (int)(TemperatureC / 0.5556);
}

Api.http

@BaseAddress = https://localhost:????

###
GET {{BaseAddress}}/limit

###
GET {{BaseAddress}}/unlimit

Ref: Microsoft

DEV Community: adhakshinamoorthy

Exception handling in .NET 8: IExecptionHandler

ApiResponse.cs

AppExceptionHandler.cs

Program.cs

Output

Rate limiting middleware in .NET 8: Fixed Window Limiter

Program.cs

Api.http