Dependencies Injection on IDocumentSessionListener

[eliecer2323]

Hello everyone, I'm trying to integrate an interceptor of CRUD operation to an specific table for doing another operations, so I found the IDocumentSessionListener interface for doing it

Here is my custom listener:

public class LedgerListener : IDocumentSessionListener
    {
        private readonly ICSVService _csvSvc;

        public LedgerListener(ICSVService csvSvc)
        {
            _csvSvc = csvSvc;
        }

        public async Task BeforeSaveChangesAsync(IDocumentSession session, CancellationToken token)
        {
            IUnitOfWork pendingChanges = session.PendingChanges;

            IEnumerable<Ledger> pendingLedgerInserts = pendingChanges.InsertsFor<Ledger>();

            foreach (Ledger record in pendingLedgerInserts)
            {
                _csvSvc.CreateSheet(record);
            }
        }
}

My service:

public class CSVService : ICSVService
{
        private readonly IDocumentStore _documentStore;

        public CSVService(IDocumentStore documentStore)
        {
            _documentStore = documentStore;
        }

        public void CreateSheet(Ledger contract)
        {
            using (var session = _documentStore.LightweightSession())
            {
                Console.WriteLine("Some proccess ...");
            }
        }
}

And here is the listener additions in the Startup.cs:

        ...previous code...
        services.AddTransient<ICSVService, CSVService>();
        services.AddScoped<IDocumentStore>(provider =>
                DocumentStore.For(_ =>
                {
                    _.AutoCreateSchemaObjects = AutoCreate.CreateOrUpdate;
                    _.Connection(cn);
                    _.Listeners.Add(new LedgerListener());
                }));
        ...next code...

But my current trouble is that I don't find any way to do the dependencies injection for the ICSVService and its dependency IDocumentStore, is there a way to do the CDI in the _.Listeners.Add(new LedgerListener()); code line? I can't simply pass the instances manually because there could be too many dependencies with their own dependencies

[jeremydmiller]

@eliecer2323 You can add additional document session listeners to an IDocumentSession after it's created. So one way to do what I think you need to do here is change your IoC registrations for IDocumentSession to add the necessary listeners inside a Lambda service registration. You can utilize the DI container right then and there to pull out whatever you need.

If you're in v4, you can use a custom factory to build document sessions I can dig up for you if you want. We're still updating docs for v4 and we're behind.

[eliecer2323]

Hi @jeremydmiller thanks for your support I appreciate it.

do you suggest to use the IDocumentSession instead of the IDocumentStore , but then I'd need to add the listeners on each place I instantiate a IDocumentSession and my objective is to subscribe a process to CRUD operations to that specific table independently on who does that without the need to have knowledge of this. I didn't get your thought about pulling out the dependencies from the DI container, I have very limited knowledges about .Net, could you dig in it please and maybe give me a code example please?

[amferguson]

Late to the party, but I had this same question a few days ago, and this discussion pointed me in the right direction (thanks!). This example is specifically for Autofac, but @jeremydmiller's suggestion to do it as a lambda registration ought to translate to any other DI system that supports it. I did something (basically) like this:

builder.Register(r =>
   {
       var session = r.Resolve<IDocumentStore>().DirtyTrackedSession();
       session.Listeners.Add(r.Resolve<ApplicationStoreListener>()); //ApplicationStoreListener requires other services 
       return session;
   }).As<IDocumentSession>().InstancePerLifetimeScope();

where builder is the Autofac ContainerBuilder and ApplicationStoreListener is an implementation of IDocumentSessionListener that requires other services that are registered with the container. Then, wherever we want this type of session, we just inject an IDocumentSession and get one with the listener added to its list.

[jeremydmiller]

There's an overload of AddMarten() that lets you supply a Func<IServiceProvider, StoreOptions> model to configure Marten. That would let you set up whatever you want here. That or you can supply your own ISessionBuilder if the listener is per session.