I'm using Autofac for dependency injection in my .NET application. I have a scenario where I want to register a service as a singleton and its dependency as InstancePerDependency. Here's a simplified example of what I'm trying to achieve:
builder.Register(c => new ClassA()).As<IClassA>().InstancePerDependency();
builder.Register(c => new ClassB(c.Resolve<IClassA>()))
.As<IClassB>()
.SingleInstance();
Will registering ClassB as a singleton affect IClassA's InstancePerDependency lifetime scope in this setup? If so, how can I achieve a singleton IClassA while ensuring that IClassA follows an InstancePerDependency lifetime scope?
In Autofac, when you register a service as a singleton and its dependency as InstancePerDependency, the singleton service (ClassB in your case) will hold onto a single instance of its dependency (ClassA in your case) throughout its lifetime. This means that every time ClassB
is resolved, it will use the same instance of ClassA
.
If you want ClassA
to follow an InstancePerDependency lifetime scope while ensuring that ClassB
remains a singleton, you can achieve this by registering ClassA
as a factory delegate rather than a concrete instance. Here's how you can modify your registration:
builder.Register(c => new ClassA()).As<IClassA>().InstancePerDependency();
builder.Register(c =>
{
var classAFactory = c.Resolve<Func<IClassA>>();
return new ClassB(classAFactory());
})
.As<IClassB>()
.SingleInstance();