Override ISolrOperations dependency injection lifetime

[gdau]

Hi,

I am attempting to consume the solr API from a IHostedService implementation (i.e. outside of a web application - this console application will maintain the search index).

As per the instructions, I am registering the necessary dependencies with this built-in call during ConfigureServices:

services.AddSolrNet("mysearch");

which internally registers the ISolrOperations<> type as having Scoped lifetime. This is fine for a web application where the scope is generally tied to the request lifetime but it does create issues when trying to inject my class which has a dependency on ISolrOperations into the IHostedService (since IHostedService has a lifetime of Singleton by default).

I have gotten around this by adding this line straight after the registration above which effectively replaces the Scoped lifetime with a Transient lifetime.

services.AddTransient(typeof(ISolrOperations<>), typeof(SolrInjectionServer<>));

Is there any particular reason why the lifetime is set to scoped and would there be any side-effects of making it transient or singleton? Would it be possible to override this behaviour in future?

Thank you!

g

[mausch]

Hi, I'm curious what issues does this cause?

[gdau]

Hi, I'm curious what issues does this cause?

Do you mean what issues does it cause if you don't use my workaround?

There is a DI exception raised immediately during startup of the console application because you cannot inject a scoped service into a service with a singleton lifetime. The pattern to get around this is to inject a IServiceProvider and create a scope inside the singleton but I'm not in control of the hosting service and it seems like it's a waste of time if I could rather just change the lifetime of the solr service without any side-effects.

[mausch]

Ah yeah, I forget the MS container throws in that situation.
You can easily just change service lifetimes... something like this should work:

        static void MakeSolrNetTransient(IServiceCollection services)
        {
            var solrNetServices = services
                .Where(s => s.ServiceType.Namespace.StartsWith("SolrNet"))
                .Where(s => s.ImplementationInstance == null)
                .ToList();
            foreach (var service in solrNetServices)
            {
                services.Remove(service);
                if (service.ImplementationFactory != null)
                {
                    services.Add(ServiceDescriptor.Transient(service.ServiceType, service.ImplementationFactory));
                } else if (service.ImplementationType != null)
                {
                    services.Add(ServiceDescriptor.Transient(service.ServiceType, service.ImplementationType));
                }
            }
        }