One More Lib For MediatR

As the name suggests, a new library that extends MediatR with integrated PipelineBehavior:

• Performance Logger
• MemoryCache
• Validation with FluentValidation
• Retry Pattern with Polly

Installing One.More.Lib.For.MediatR

Link to the nuget package

We recommend using NuGet:

Install-Package One.More.Lib.For.MediatR

Or via the .NET Core command line interface:

dotnet add package One.More.Lib.For.MediatR

Performance Logger PipelineBehavior

How to configure it?

The simplest way:

builder.Services.AddMediatRExtensions(cfg => cfg.PerformanceLoggerSupport = true);

If you want to configure it:

builder.Services.AddMediatRExtensions(cfg => cfg.AddPerformanceLoggerSupport(500));

How yo use it?

Nothing to do. Requests exceeding th threshold will be logged.

MemoryCache PipelineBehavior

How to configure it?

The simplest way:

builder.Services.AddMediatRExtensions(cfg => cfg.MemoryCacheSupport = true);

If you want a complete configuration:

builder.Services.AddMediatRExtensions(cfg => cfg.AddMemoryCacheSupport(slidingExpiration: TimeSpan.FromMinutes(10), priority: CacheItemPriority.Low));

All the possible options are:

• DateTimeOffset? AbsoluteExpiration
  

• TimeSpan? AbsoluteExpirationRelativeToNow
  

• TimeSpan? SlidingExpiration
  

• CacheItemPriority Priority
  

You can also create a specific configuration with the same options for a given request:

builder.Services.AddMediatRExtensions(cfg =>
{
  cfg.AddMemoryCacheSupport(slidingExpiration: TimeSpan.FromMinutes(10), priority: CacheItemPriority.Low);
  cfg.AddMemoryCacheSupportOverrideFor<GiveRequest>(priority: CacheItemPriority.High);
}

How yo use it?

Just add [MemoryCache] attribute on requests classes or records.

[MemoryCache]
public class GetUserByName : IRequest<User?>
{
    public string Name { get; set; }
}

Validation with FluentValidation

How to configure it?

There is not simplest way because you need to enter the assemblies to be scanned for FluentValidation:

builder.Services.AddMediatRExtensions(cfg => cfg.AddFluentValidationSupport(new[] { typeof(Program).Assembly }));

How to use it?

Nothing to do, just create Validation rules. If a rule is not respected a ValidationException will be thrown.

Retry Pattern with Polly

How to configure it?

The simplest way:

builder.Services.AddMediatRExtensions(cfg => cfg.RetrySupport = true);

If you want to configure it:

builder.Services.AddMediatRExtensions(cfg => cfg.AddRetrySupport(retryCount: 3, retryDelay: 100));

When to use it?

• For example, when you call on external resources and the infrastructure can sometimes have temporarey failures.
• Or when you want to deal with the database and there may be temporary conflicts.

How to use it?

Just add [RetryPolicy] attribute on requests classes or records.

[RetryPolicy]
public class GetProduct : IRequest<Product>
{
    public Guid ProductId { get; set; }
}

Or you can override default values by passing them in the RetryPolicy Attribute

[RetryPolicy(OverrideRetryCount = true, RetryCount = 5)]
public class GetProduct : IRequest<Product>
{
    public Guid ProductId { get; set; }
}

[RetryPolicy(OverrideRetryDelay = true, RetryDelay = 200)]
public class GetProduct : IRequest<Product>
{
    public Guid ProductId { get; set; }
}