DependencyInjection.Interception

A library to perform interception based AOP using .Net Core DI

Introduction

Extend .NET Core DI to create proxy wrapper around service class instances to intercept method execution

• execute custom code before and/or after method execution to inject dynamic behavior
• modularize cross cutting concerns (logging, caching, security, etc.) into their own classes
• flexibility to control which class/methods should be intercepted

Getting Started

1. Install package from nuget dotnet add package DependencyInjection.Interception
2. Create one or more class that will perform interception by inheriting from Interceptor class and overriding PreInterceptor and PostInterceptor methods as needed

public class LogInterceptor : Interceptor
{
    public override void PreInterceptor(InterceptionContext context)
    {
        //Do pre-interception here...
    }

    public override void PostInterceptor(InterceptionContext context)
    {
        //Do post-interception here...
    }
}

3. Register interception class(es) to ServiceCollection

var services = new ServiceCollection();
services.AddSingleton<LogInterceptor>();

4. Decorate class to be intercepted with Interceptable attribute

[Interceptable]
public class Foo : IFoo
{
    ...
}

5. Decorate Interceptor(Type) attribute to class (or methods) by passing type of Interception class

[Interceptable]
[Interceptor(typeof(LogInterceptor))]
public class Foo : IFoo
{
    ...
}

6. Ensure methods are marked as virtual to ensure they can be intercepted

[Interceptable]
[Interceptor(typeof(LogInterceptor))]
public class Foo : IFoo
{
    public virtual void Bar()
    {
        ...
    }
}

7. Register service class(es) to ServiceCollection

var services = new ServiceCollection();
services.AddSingleton<LogInterceptor>();
services.AddTransient<IFoo, Foo>();

8. Build interceptable provider using BuildServiceProviderWithInterception() method

var provider = services.BuildServiceProviderWithInterception();

9. Get service class instance from IServiceCollection

var foo = provider.GetService<IFoo>();