Question

I am using Autofac 2.4.5.724 under vb.net 2010. I have several classes without default constructors that I want autofac to resolve, and I want to register them using RegisterAssemblyTypes (not registering the classes one by one). Is it possible?

My interface is like this:

Namespace Repo
    Public Interface IPeople
        Function All() As IList(Of RCO.People)
    End Interface
End Namespace

The implementation is like this:

Namespace Repo
    Public Class People
        Inherits Base
        Implements IPeople

        Public Sub New(ByVal cs As String)
            MyBase.New(cs)
        End Sub

        Public Function All() As IList(Of RCO.People) Implements IPeople.All
            ...
        End Function

    End Class
End Namespace

I can register the classes one by one like this:

Dim builder = New ContainerBuilder
builder.Register(
    Function(x) New MyLib.Repo.People("Data Source=localhost...")
).As(Of MyLib.Repo.IPeople)()
Dim container = builder.Build
Dim peep = container.Resolve(Of MyLib.Repo.IPeople)()

But I don’t want to register the classes one by one, I want autofac to scan my assembly:

Dim builder = New ContainerBuilder
builder.RegisterAssemblyTypes(Reflection.Assembly.Load("MyLib")).Where(
    Function(x) x.Namespace = "Repo").AsImplementedInterfaces() ...what else?...
Dim container = builder.Build
Dim peeprepo = container.Resolve(Of ReportCenterLib.Repo.IPeople)()

Alternatively, can I put constructor parameter during resolve?

Dim peeprepo = container.Resolve(Of ReportCenterLib.Repo.IPeople)(...here?...)

Answer 1

You can definitely specify the parameter when resolving. You just need to add one or more TypedParameters created using the actual parameters to the Resolve call; you can’t pass them directly:

Dim peeprepo = container.Resolve(Of ReportCenterLib.Repo.IPeople)(TypedParameter.From("Data Source=localhost..."))

Now, when Autofac sees a constructor for the registered type that accepts a string, it will substitute the given parameter. Understand that Autofac will get confused if you have a constructor that takes multiple strings; in that case, you’ll need to specify each string as a named parameter which Autofac will match to the constructor parameter names. This has its own complexities; see the SO question here: Autofac parameter passing