When does a DbContext instance get disposed in ASP.NET Core 5

Question

I'm using the recommended approach to create DbContext instance through dependency injection.

In Startup.cs -

services.AddDbContext<DashboardContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DashboardConnection")));

and in the Controller -

private readonly DashboardContext db;
public AccountController(DashboardContext context)
{
    db = context;
}

What I want to know is when this instance gets disposed.

Previously we would always use the using statement which would dispose on close of braces -

using (DashboardContext db = new DashboardContext())
{
    // Query
}

AddDbContext<>() registers the DBContext as a service with ServiceLifetime.Scoped which means that your DbContext is created per web request. It is disposed when request is completed. — jazb
– jazb, Commented Jan 27, 2021 at 5:19
The DbContext will be disposed as soon as the request ends. This gives you "transaction-per-request" out of the box - if you don't want to persist changes, don't call SaveChanges before exiting the action. — Panagiotis Kanavos
– Panagiotis Kanavos, Commented Jan 27, 2021 at 7:26

atiyar · Accepted Answer · 2021-01-30 15:45:08Z

7

With the AddDbContext method, a DbContext will be created with Scoped lifetime by default; which means, it's lifetime is scoped within the current request, and it will get disposed as soon as the current request completes.

But you can override the default by passing a value for the contextLifetime parameter, like -

services.AddDbContext<DashboardContext>(options => 
    options.UseSqlServer(
        Configuration.GetConnectionString("DashboardConnection")),
        ServiceLifetime.Transient);

For further detail check - AddDbContext

EDIT - (in reply to @Dale's comment) :
Considering the overall architecture of the ASP.NET Core MVC, and how we tend to use the framework, I'd say (personal opinion) that in general for most applications its better to stick to the default Scoped lifetime.
In the answer, I just wanted to make it clear that the option for manual config is there for you. Of course, there might be use cases or scenarios (depending on how you design your own application) where the manual config has its use.

edited Jan 30, 2021 at 15:45

answered Jan 27, 2021 at 5:30

atiyar

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2 Comments

Dale Fraser Over a year ago

Thats super helpfull, Im a little unsure on in a normal ASP.NET Core 5 MVC application if Scoped or Transient is better I read your link and while it explains them, its not clear what would work best.

mjwills Over a year ago

@DaleFraser Let's say a controller has a dependency on IBob and ICathy. Cathy (the ICathy) also has a dependency on IBob. Do you want the controller and Cathy to share the same IBob? If so - IBob should be Scoped. If not - IBob should be Transient. Disposal wise - Transient and Scoped will act the same, they'll Dispose when the web request ends. I'd argue for most scenarios Transient is the safer default.

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