How to access DbContext in/from Program class?

Question

I have setup an ASP.NET Core project, and configured the DbContext in Startup.cs like -

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<DBContext>(options =>
        options.UseSqlServer(Configuration["ConnectionStrings:DefaultConnection"]));
}

I can access the DbContext object in controller classes with dependency injection. But I need a reference of the DbContext in the Program class (in Program.cs file).

I tried the following approach, but it indicates syntax error -

public class Program
{
    public static void Main(string[] args)
    {
        using (var db = new DBContext())    // getting syntax error here
        {
            db.Database.EnsureCreated();
        }
        CreateHostBuilder(args).Build().Run();
    }


    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>()
                    .UseUrls("http://localhost:4000");
            });
}

So, how to get access to the DbContext object in the Program class?

I need to find a way to get dbcontext in program.cs like we access the same in any other controller.. — Sunny Singh
– Sunny Singh, Commented Dec 22, 2020 at 11:56

poke · Accepted Answer · 2020-12-22 12:36:01Z

Since you have registered and configured your database context using dependency injection, you cannot just create a context using new since you would be skipping the configuration that way.

Instead, you will need to retrieve the database context from the dependency injection service provider, which is available from the Host that is being built in your Program.

Since the database context has a scoped lifetime by default, you will need to create a scope first, retrieve the database context within that scope, and finally dispose the scope again when you are done.

This should look like this:

public static void Main(string[] args)
{
    var host = CreateHostBuilder(args).Build();

    using (var scope = host.Services.CreateScope())
    {
        var db = scope.ServiceProvider.GetRequiredService<DBContext>();
        db.Database.EnsureCreated();
    }

    host.Run();
}

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