CODEWITHSUNDEEP
entity-frameworksqliteasp.net-core-webapiasp.net-core-2.1ef-core-2.1
Hairydruidy
Hairydruidy

Reputation: 107

Dependency Injection, EF Core + web api 2 architecture

My layout

project.web (.net core 2.1 web api)

Some binding models (for post/put requests) and resource models for GET requests Controllers. I only call interfaces from (x.api) which are resolved to x.core services. No validation or anything. This happens inside the core layer I've setup a few things like automapper and swagger, that are not relevant for my question.

project.api (class lib)

only contains interfaces for .core and .store projects (services, repositories and domain models)

project.core (class lib)

two kinds of services

1) Services which call the repository services (interfaces). But validate the data before calling the repo service.

2) Services that will have to execute long term stuff (IE: scanning folders, handling file information, ...). I actually created HostedServices for these as a folder could easily contain thousands of files.

project.store (class lib)

Wrapper services for my storage (Only contains helper methods so I don't have to write the same queries a hundred times.)

Problem / question

At this time I have registered all of my services and repositories as singletons in public void ConfigureServices(IServiceCollection services) because I was using a different storage (nosql, litedb) before refactoring code to EF (sqllite)

Now the problem is that I want to register my DbContext as scoped (by default) But my repositories (singleton) depend on dbcontext. Which means I will have to make these scoped as well. I'm ok with this, as these are only wrapper services, so I don't have to write the same queries all the time.

But some other services, that will need access to my data are singletons, and I cannot register these as scoped. Contains some data that needs to be the same for every request, and some collections and long running jobs.

I can think of two solutions

The first solution is to make a dependency to IServiceScopeFactory in my repository and use something like using (var scope = ServiceScopeFactory.CreateScope()) { scope.ServiceProvider.GetService(typeof(MyDbContext))... }

this way I can remove the dependency from my repository wrapper, but this doesn't sound clean to me.

The other solution is to register all of my services that only handle database stuff as scoped. (IE customerSservice in core only does validations and calls customerRepository) I remove dependencies from my remaining singleton services. In those singletons, instead of depending on the customersService, I could use a rest call with restsharp or something similar

Just like how I would consume them from my windows client applications and web client apps.

I don't actually like either. But perheps someone can give me some advice or thoughts?

Upvotes: 0

Views: 401

Answers (1)

Chris Pratt
Chris Pratt

Reputation: 239430

Well, the two options you laid out are in fact your only two options. The first is the service locator antipattern, which as the name implies, is something you should avoid. However, when you are dealing with singleton-scoped objects needing access to objects in other scopes, there is no other way.

The only other option is to reduce the scope of your services from singletons, such that you can then inject the context directly. Not everything necessarily needs to be a singleton. Generally, if you need to utilize something like DbContext, there's a strong argument to be made that your object should not be singleton-scope in the first place. If you need it to be singleton-scoped, that's most likely an indication that the class is either doing too much or is otherwise brittle.

Upvotes: 1

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