Understanding CQRS

Command Query Responsibility Segregation (CQRS) separates read and write operations, allowing for optimized data models and better scalability.

Implementation with MediatR

MediatR provides an excellent foundation for implementing CQRS in .NET applications:

public record CreateOrderCommand : IRequest<int>
{
    public string CustomerId { get; init; }
    public List<OrderItem> Items { get; init; }
}

public class CreateOrderCommandHandler : IRequestHandler<CreateOrderCommand, int>
{
    public async Task<int> Handle(CreateOrderCommand request, CancellationToken cancellationToken)
    {
        // Command handling logic
    }
}
                        

Event Sourcing Benefits

• Complete audit trail
• Temporal queries
• Event replay capabilities
• Better debugging and troubleshooting

When to Use CQRS

CQRS is particularly useful in complex domains with different read and write requirements, high-performance needs, or when you need detailed audit trails.