Create scope factory in asp.net core

问题

I want to create scoped container in asp.net core and use it in 2 methods of my singleton method.

I've tried create this in each method of sigleton. it works, but i think it is overhead.

        var scopeFactory = _serviceProvider.GetService<IServiceScopeFactory>();
        var scope = scopeFactory.CreateScope();
        var scopedContainer = scope.ServiceProvider;

I write it in each method when i need it. I think it is logic mistake. Please, explain me how to do it correct? thank you

回答1:

It is technically not incorrect the way you do it. If you are within a singleton service and you need to access scoped services, then you should create a new service scope and retrieve the services from that scope’s service provider. And when you are done, you should also dispose the scope.

In practice, you can simplify this a bit. You should avoid having to inject IServiceProvider directly into a service. Instead, you can just inject the IServiceScopeFactory directly. And then you should also create the scope with a using statement to make sure that it is disposed properly after use.

So an example singleton service could look like this:

public class ExampleSingletonService
{
    private readonly IServiceScopeFactory _serviceScopeFactory;

    public ExampleSingletonService(IServiceScopeFactory serviceScopeFactory)
    {
        _serviceScopeFactory = serviceScopeFactory;
    }

    public async Task DoSomethingAsync()
    {
        using (var scope = _serviceScopeFactory.CreateScope())
        {
            var db = scope.ServiceProvider.GetService<MyDbContext>();

            db.Add(new Foo());
            await db.SaveChangesAsync();
        }
    }
}

As you can see, there isn’t really that much overhead for this. But of course this makes you think twice about whether you want to use a scoped service within a singleton or not.

来源：https://stackoverflow.com/questions/55381340/create-scope-factory-in-asp-net-core