Cannot resolve scoped service from root provider in ASP.NET Core 6 [duplicate]

Question

I'm coding a website with ASP.NET Core 6. It's originally a tutorial from YouTube with .NET Core 3. So I'm facing migration issues. Here, I have a DbInitializer file which contains all my data (i.e.: my database).

using DrinkAndGo.Data.Models;
using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using System.Collections.Generic;
using System.Linq;

namespace DrinkAndGo.Data
{
public class DbInitializer
{
    public static void Seed(IApplicationBuilder applicationBuilder)
    {
        AppDbContext context =
            applicationBuilder.ApplicationServices.GetRequiredService<AppDbContext>();

        if (!context.Categories.Any())
        {
            context.Categories.AddRange(Categories.Select(c => c.Value));
        }

        if (!context.Drinks.Any())
        {
            context.AddRange
            (
                new Drink
                {
                    Name = "Beer",
                    Price = 7.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/beerL_2.jpg",
                    InStock = true,
                    IsPreferredDrink = true,
                    ImageThumbnailUrl = "http://imgh.us/beerS_1.jpeg"
                },
                new Drink
                {
                    Name = "Rum & Coke",
                    Price = 12.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/rumCokeL.jpg",
                    InStock = true,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/rumAndCokeS.jpg"
                },
                new Drink
                {
                    Name = "Tequila ",
                    Price = 12.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/tequilaL.jpg",
                    InStock = true,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/tequilaS.jpg"
                },
                new Drink
                {
                    Name = "Wine ",
                    Price = 16.75M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/wineL.jpg",
                    InStock = true,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/wineS.jpg"
                },
                new Drink
                {
                    Name = "Margarita",
                    Price = 17.95M,
                   
                    ImageUrl = "http://imgh.us/margaritaL.jpg",
                    InStock = true,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/margaritaS.jpg"
                },
                new Drink
                {
                    Name = "Whiskey with Ice",
                    Price = 15.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/whiskyIceL.jpg",
                    InStock = false,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/whiskeyS.jpg"
                },
                new Drink
                {
                    Name = "Jägermeister",
                    Price = 15.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/jagermeisterL.jpg",
                    InStock = false,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/jagermeisterS.jpg"
                },
                new Drink
                {
                    Name = "Champagne",
                    Price = 15.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/champagneL.jpg",
                    InStock = false,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/champagneS.jpg"
                },
                new Drink
                {
                    Name = "Piña colada ",
                    Price = 15.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/pinaColadaL.jpg",
                    InStock = false,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/pinaColadaS.jpg"
                },
                new Drink
                {
                    Name = "White Russian",
                    Price = 15.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/whiteRussianL.jpg",
                    InStock = false,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/whiteRussianS.jpg"
                },
                new Drink
                {
                    Name = "Long Island Iced Tea",
                    Price = 15.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/longTeaL.jpg",
                    InStock = false,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/islandTeaS.jpg"
                },
                new Drink
                {
                    Name = "Vodka",
                    Price = 15.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/vodkaL.jpg",
                    InStock = false,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/vodkaS.jpg"
                },
                new Drink
                {
                    Name = "Gin and tonic",
                    Price = 15.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/ginTonicL.jpg",
                    InStock = false,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/ginTonicS.jpg"
                },
                new Drink
                {
                    Name = "Cosmopolitan",
                    Price = 15.95M,
                    
                    Category = Categories["Alcoholic"],
                    ImageUrl = "http://imgh.us/cosmopolitanL.jpg",
                    InStock = false,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/cosmopolitanS.jpg"
                },
                new Drink
                {
                    Name = "Tea ",
                    Price = 12.95M,
                    
                    Category = Categories["Non-alcoholic"],
                    ImageUrl = "http://imgh.us/teaL.jpg",
                    InStock = true,
                    IsPreferredDrink = true,
                    ImageThumbnailUrl = "http://imgh.us/teaS.jpg"
                },
                new Drink
                {
                    Name = "Water ",
                    Price = 12.95M,
                    
                    Category = Categories["Non-alcoholic"],
                    ImageUrl = "http://imgh.us/waterL.jpg",
                    InStock = true,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/waterS_1.jpg"
                },
                new Drink
                {
                    Name = "Coffee ",
                    Price = 12.95M,
                    
                    Category = Categories["Non-alcoholic"],
                    ImageUrl = "http://imgh.us/coffeeL.jpg",
                    InStock = true,
                    IsPreferredDrink = true,
                    ImageThumbnailUrl = "http://imgh.us/coffeS.jpg"
                },
                new Drink
                {
                    Name = "Kvass",
                    Price = 12.95M,
                    
                    Category = Categories["Non-alcoholic"],
                    ImageUrl = "http://imgh.us/kvassL.jpg",
                    InStock = true,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/kvassS.jpg"
                },
                new Drink
                {
                    Name = "Juice ",
                    Price = 12.95M,
                    
                    Category = Categories["Non-alcoholic"],
                    ImageUrl = "http://imgh.us/juiceL.jpg",
                    InStock = true,
                    IsPreferredDrink = false,
                    ImageThumbnailUrl = "http://imgh.us/juiceS.jpg"
                }
            );
        }

        context.SaveChanges();
    }

    private static Dictionary<string, Category> categories;
    public static Dictionary<string, Category> Categories
    {
        get
        {
            if (categories == null)
            {
                var genresList = new Category[]
                {
                    new Category { CategoryName = "Alcoholic", Description="All alcoholic drinks" },
                    new Category { CategoryName = "Non-alcoholic", Description="All non-alcoholic drinks" }
                };

                categories = new Dictionary<string, Category>();

                foreach (Category genre in genresList)
                {
                    categories.Add(genre.CategoryName, genre);
                }
            }

            return categories;
        }
    }
}
}

Then my Program.cs file:

using DrinkAndGo.Data;
using DrinkAndGo.Data.Interfaces;
using DrinkAndGo.Data.Mocks;
using DrinkAndGo.Data.Repositories;
using Microsoft.EntityFrameworkCore;
using static System.Net.Mime.MediaTypeNames;

var builder = WebApplication.CreateBuilder(args);

builder.Host.ConfigureServices(services =>
{
    services.AddTransient<IDrinkRepository, DrinkRepository>(); 
    services.AddTransient<ICategoryRepository, CategoryRepository>();
    services.AddScoped<AppDbContext>();

});

builder.Services.AddControllersWithViews();
builder.Services.AddDbContext<AppDbContext>(options => options.UseSqlServer(
    builder.Configuration.GetConnectionString("DefaultConnection")
    ));

var app = builder.Build();


if (app.Environment.IsDevelopment())
{
    app.UseDeveloperExceptionPage();
}
else
{
    app.UseExceptionHandler("/Home/Error");
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();
app.UseRouting();
app.UseAuthorization();

DbInitializer.Seed(app);
app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Home}/{action=Index}/{id?}"
    );


app.Run();

When I run the app, with IIS Express, Visual Studio throws the following exception:

System.InvalidOperationException : 'Cannot resolve scoped service 'DrinkAndGo.Data.AppDbContext' from root provider.'

Could someone explain me the problem and how to solve it?

Compressive

Answer 1

You need to create a scope to resolve Scoped services. Use ServiceProviderServiceExtensions.CreateScope:

public static void Seed(WebApplication app)
{
     using var scope = app.Services.CreateScope();
     AppDbContext context = scope.ServiceProvider.GetRequiredService<AppDbContext>();

    // use context
}

Romeo

just note if you use the using in the constructor it will destroy it before you can use it in your methods. – Moisture

As B.Ramburn said, you should not use the 'using' while creating the scope. Otherwise you should get an exception like this: System.ObjectDisposedException: Cannot access a disposed context instance. – Annoyance

@Annoyance it depends on the use case. The provided method signature and implementation does not imply using the context outside the Seed method so using is just fine there. I would say that even more - you should use using unless the ownership of it is transferred, then you should transfer ownership of the scope itself – Romeo

This worked for me when adding a DI for a Quartz job, thanks! – Aphasic