builder.Services.AddDbContext<MyContext>(ServiceLifetime.Transient)?

[michaelcsikos]

In a Blazor solution, sometimes I get the following error:

A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext.

Is the solution ServiceLifetime.Transient or are there side effects to this approach?

[rockfordlhotka]

Transient lifetime means that you get a new instance of the service each time you ask for one.

Scoped lifetime means that you get a new instance of the service if there isn't already one in the current scope.

Singleton lifetime means that you get a new instance of the service only once during the lifetime of the app.

The local data portal creates a new scope when the code hits the logical server-side code, and disposes that scope before returning to the logical client. All server-side code executing during each data portal call runs in that scope.

Generally speaking, a remote data portal call works the same way, because aspnetcore creates a scope, the server-side code runs in that scope, and the scope is disposed at the end of the call.

[jhuerta3]

Hello @michaelcsikos ,

Im getting a error similar to this topic. I working on a Blazor control with pagination. May I ask how you resolved the issue? My error is below.

A second operation was started on this context instance before a previous operation completed. This is usually caused by different threads concurrently using the same instance of DbContext. For more information on how to avoid threading issues with DbContext, see https://go.microsoft.com/fwlink/?linkid=2097913.

[michaelcsikos]

I have been using ServiceLifetime.Transient. In Program.cs:

builder.Services.AddDbContext<EfDbContext>(options => options.UseSqlServer(builder.Environment.IsProduction()
                                                                           ? PRODUCTION_CONNECTION_STRING
                                                                           : DEVELOPMENT_CONNECTION_STRING),
                                           ServiceLifetime.Transient);

Each of my Dal classes call DbContext.SaveChanges() for their own changes so I'm quite happy for each one to get a new instance. It's much better than getting this horrible exception.

[jhuerta3]

Thank you.
I just realized I was using the following on my Program.cs
builder.Services.AddSingleton(s => new ASPNetContext(aspnetdb_connectionString));
so I changed it to
builder.Services.AddTransient(s => new ASPNetContext(aspnetdb_connectionString));
Thank you @michaelcsikos