How to Create a DbContextFactory in .NETCore 3.1 & Blazor

Question

I'm following guidelines in how to setup EF Core to work safely in Blazor & .NET Core 3.1. The MS documentation is here: https://docs.microsoft.com/en-us/aspnet/core/blazor/blazor-server-ef-core?view=aspnetcore-3.1

In the instructions, advice is to create a DbContextFactory which is used to create a dbcontext in each service. All makes sense in the Blazor world, but the code won't compile as AddDbContextFactory does not exist. If there's another way to do it in .Net Core 3.1/ EF Core 3 - I can't see it.

services.AddDbContextFactory<ContactContext>(opt =>
    opt.UseSqlite($"Data Source={nameof(ContactContext.ContactsDb)}.db")
    .EnableSensitiveDataLogging());

Answer 1

AddDbContextFactory will be introduced in .NET Core 5. See here: https://devblogs.microsoft.com/dotnet/announcing-entity-framework-core-ef-core-5-0-preview-7/.

Answer 2

The page you linked to gives you the code (albeit in pieces) to roll your own.

You will have to add the AddDbContextFactory<TContext> class and the FactoryExtensions to your project. Download the sample app there to make it complete.

And when you upgrade to net5 just replace it with the library version.