Sitecore: inject dependency into sitecore components - dependency-injection

Question

I'm using Sitecore 8.1 MVC with Autofac as the DI. I was wondering what is the recommended way to injecting resolved objects into sitecore created objects i.e. pipelines, commands, computed fields etc... As an example, i am using a membership provider in which i need to invoke my business layer. Is it possible for me to define a constructor on the class and sitecore would injects the objects?
Thanks

Answer 1

With things like pipeline processors, commands etc... Basically anything that Sitecore creates - you are fairly limited. The normal approach is to use the Service Locator pattern to resolve dependencies:
var membershipProvider = DependencyResolver.Current.Resolve<IMembershipProvider>()
There are other ways tho. This post: https://cardinalcore.co.uk/2014/07/02/sitecore-pipelines-commands-using-ioc-containers/ uses a container factory class to resolve the dependencies in the pipeline. This is the class used:
using System;
using System.Diagnostics.CodeAnalysis;
using Sitecore.Reflection;
public class ContainerFactory : IFactory
{
private readonly IContainerManager containerManager;
public ContainerFactory() : this(new LocatorContainerManager()) // service locate an appropriate container
{
}
public ContainerFactory(IContainerManager containerManager)
{
this.containerManager = containerManager;
}
public object GetObject(string identifier)
{
Type type = Type.GetType(identifier);
return this.containerManager.Resolve(type);
}
}
Then this would be setup as the factory for the event or processor using the factory attribute in the config. Example config:
<sitecore>
<events>
<event name="item:saved">
<handler factory="ContainerFactory" ref="MyApp.MyHandler, MyApp" method="MyMethod">
<database>master</database>
</handler>
</event>
</events>
<pipelines>
<MyPipeline>
<processor type="1" factory="ContainerFactory" ref="MyApp.MyProcessor, MyApp" />
</MyPipeline>
</pipelines>
<factories>
<factory id="ContainerFactory" type="MyApp.ContainerFactory"></factory>
</factories>
</sitecore>
With this second method, you can inject your dependencies in your constructor as you normally would.
These are probably the 2 most commonly used options.