Error Handling Study Portal

Common pitfalls

❌ Anti-Pattern 1: Overly Defensive Core Logic

// Bad: Hiding bugs with defensive checks in domain logic
public class Order
{
    public void SetQuantity(decimal quantity)
    {
        // Too defensive - silently ignoring invalid input
        if (quantity <= 0)
        {
            _logger.LogWarning("Invalid quantity ignored");
            return; // BUG IS HIDDEN!
        }
        Quantity = quantity;
    }
}

// Good: Fail-fast in domain logic
public class Order
{
    public void SetQuantity(decimal quantity)
    {
        if (quantity <= 0)
            throw new ArgumentException("Quantity must be positive");

        Quantity = quantity;
    }
}

❌ Anti-Pattern 2: Fail-Fast at API Boundaries

// Bad: Throwing raw exceptions from controller
[HttpPost]
public IActionResult CreateOrder([FromBody] CreateOrderRequest request)
{
    // Too fail-fast - letting exceptions crash through
    var order = new Order(request.Symbol, request.Quantity, request.Price);
    // ArgumentException crashes the request
    return Ok(order);
}

// Good: Defensive at boundary
[HttpPost]
public IActionResult CreateOrder([FromBody] CreateOrderRequest request)
{
    try
    {
        var order = new Order(request.Symbol, request.Quantity, request.Price);
        return Ok(order);
    }
    catch (ArgumentException ex)
    {
        return BadRequest(ex.Message);
    }
}

❌ Anti-Pattern 3: Silent Failures

// Bad: Swallowing exceptions
public decimal CalculatePrice()
{
    try
    {
        return _priceCalculator.Calculate();
    }
    catch
    {
        return 0; // Silent failure - debugging nightmare
    }
}

// Good: Log and re-throw or handle appropriately
public decimal CalculatePrice()
{
    try
    {
        return _priceCalculator.Calculate();
    }
    catch (Exception ex)
    {
        _logger.LogError(ex, "Price calculation failed");
        throw new PriceCalculationException("Failed to calculate price", ex);
    }
}