Add a way to pass in dependencies when configuring the LINQ to HQL generator registry class

[nfplee]

I'm currently in the process of upgrading a ASP.NET app to use ASP.NET Core and NHibernate 5.1.

When I create the configuration object I say:

var configuration = new Configuration();

configuration.LinqToHqlGeneratorsRegistry<LinqToHqlGeneratorsRegistry>();
configuration.SetInterceptor(new SqlInterceptor(x));

Notice how I can feed dependencies into the constructor of the SqlInterceptor but I cannot do the same for my LinqToHqlGeneratorsRegistry class.

Here's my LinqToHqlGeneratorsRegistry class:

public class LinqToHqlGeneratorsRegistry : DefaultLinqToHqlGeneratorsRegistry {
    public LinqToHqlGeneratorsRegistry() : base() {
        var buildManager = DependencyResolver.Current.GetService<IBuildManager>();

        // Register the method generators
        foreach (var generator in buildManager.GetInstances<BaseHqlGeneratorForMethod>()) {
            this.Merge(generator);
        }

        // Register the property generators
        foreach (var generator in buildManager.GetInstances<BaseHqlGeneratorForProperty>()) {
            this.Merge(generator);
        }
    }
}

This allows me to register my method and property generators in a more modular way. However in .NET Core there is no DependencyResolver. I have found the following https://stackoverflow.com/questions/37813721/asp-net-core-dependencyresolver which describes a way to mimic the DependencyResolver but it still feels like a hack.

Ideally I'd like to be able to feed in an instance of IBuildManager into the constructor of my class.

[nfplee]

It would also be good if you can do the same thing when specifying the database dialect. Currently I say something like:

configuration.DataBaseIntegration(db => db.Dialect<CustomMsSql2008Dialect>())

But again I don't have the option to inject dependencies into CustomMsSql2008Dialect.

[fredericDelaporte]

This is a general issue with all cases where NHibernate takes a class as a configuration setting, not an instance. These "configuration by class" settings are to remain for backward compatibility, but alternate ways allowing to provide instances instead (or factories instances) should be added wherever possible.

[nfplee]

I think I've come up with a temporary way of doing this until it is baked in. I have created the following objects factory class:

public class ActivatorObjectsFactory : IObjectsFactory {
    private readonly IServiceProvider _serviceProvider;

    public ActivatorObjectsFactory(IServiceProvider serviceProvider) {
        _serviceProvider = serviceProvider;
    }

    public object? CreateInstance(Type type) {
        try {
            return ActivatorUtilities.CreateInstance(_serviceProvider, type);
        } catch {
            return Activator.CreateInstance(type);
        }
    }

    object IObjectsFactory.CreateInstance(Type type, bool nonPublic) => throw new NotImplementedException();
    object IObjectsFactory.CreateInstance(Type type, params object[] ctorArgs) => throw new NotImplementedException();
}

Now when I configure the session factory I say the following (where _serviceProvider is injected in the constructor of the class which creates the session factory):

NHibernate.Cfg.Environment.ObjectsFactory = new ActivatorObjectsFactory(_serviceProvider);