Recommended context factory injection method?

I’m looking to run some queries in parallel and understand that I’ll need to create multiple context instances for this. As such I’m looking to inject a factory rather that single instance. Would you be able to give a little guidance please as to a recommended approach?

It looks like runtime context factories aren’t something built-in, and the current DI helper:

https://github.com/aspnet/EntityFrameworkCore/blob/03bcb5122e3f577a84498545fcf130ba79a3d987/src/Microsoft.EntityFrameworkCore/EntityFrameworkServiceCollectionExtensions.cs#L142

…just registers the context type, of course.

Should I just implement my own IEfContextFactory<TContext> type which depends on DbContextOptionsFactory<TContext>? Is there a method you guys use for this scenario?

[bradmarder]

You can try this.

// inject IServiceScopeFactory _factory into ctor
using (var scope = _factory.CreateScope())
{
    var db = scope.ServiceProvider.GetRequiredService<DbContext>();
}

When scope is disposed, it will automatically dispose all instances resolved from it.

[simeyla]

One important reason this would be necessary is for retryable transactions.

The current examples in the docs for ‘Connection Resiliency’ just create a new context as needed.

It is clearly necessary not to continue with the same context if you’re ‘adding’ items to a table, and then retrying the entire operation again if it fails - you’ll get duplicates.

That’s what led me here, and I’m using connection pooling so I thought perhaps there ought to be a well defined way to reset a context - especially since I know that functionality exists as that’s how connection pools work!