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Scrutor Build status NuGet Package

Scrutor - I search or examine thoroughly; I probe, investigate or scrutinize
From scrūta, as the original sense of the verb was to search through trash. -

Assembly scanning and decoration extensions for Microsoft.Extensions.DependencyInjection


Install the Scrutor NuGet Package.

Package Manager Console

Install-Package Scrutor


dotnet add package Scrutor


The library adds two extension methods to IServiceCollection:

  • Scan - This is the entry point to set up your assembly scanning.
  • Decorate - This method is used to decorate already registered services.

See Examples below for usage examples.



var collection = new ServiceCollection();

collection.Scan(scan => scan
     // We start out with all types in the assembly of ITransientService
        // AddClasses starts out with all public, non-abstract types in this assembly.
        // These types are then filtered by the delegate passed to the method.
        // In this case, we filter out only the classes that are assignable to ITransientService.
        .AddClasses(classes => classes.AssignableTo<ITransientService>())
            // We then specify what type we want to register these classes as.
            // In this case, we want to register the types as all of its implemented interfaces.
            // So if a type implements 3 interfaces; A, B, C, we'd end up with three separate registrations.
            // And lastly, we specify the lifetime of these registrations.
        // Here we start again, with a new full set of classes from the assembly above.
        // This time, filtering out only the classes assignable to IScopedService.
        .AddClasses(classes => classes.AssignableTo<IScopedService>())
            // Now, we just want to register these types as a single interface, IScopedService.
            // And again, just specify the lifetime.
        // Generic interfaces are also supported too, e.g. public interface IOpenGeneric<T> 
        .AddClasses(classes => classes.AssignableTo(typeof(IOpenGeneric<>)))
        // And you scan generics with multiple type parameters too
        // e.g. public interface IQueryHandler<TQuery, TResult>
        .AddClasses(classes => classes.AssignableTo(typeof(IQueryHandler<,>)))


var collection = new ServiceCollection();

// First, add our service to the collection.
collection.AddSingleton<IDecoratedService, Decorated>();

// Then, decorate Decorated with the Decorator type.
collection.Decorate<IDecoratedService, Decorator>();

// Finally, decorate Decorator with the OtherDecorator type.
// As you can see, OtherDecorator requires a separate service, IService. We can get that from the provider argument.
collection.Decorate<IDecoratedService>((inner, provider) => new OtherDecorator(inner, provider.GetRequiredService<IService>()));

var serviceProvider = collection.BuildServiceProvider();

// When we resolve the IDecoratedService service, we'll get the following structure:
// OtherDecorator -> Decorator -> Decorated
var instance = serviceProvider.GetRequiredService<IDecoratedService>();