How do I access DbContext class in .NET Core 6 program class after builder.Build()?

Question

I have a DbContext class. I have registered that class using this method in my program.cs file:

using BethanyPieShop.Models;
using Microsoft.EntityFrameworkCore;

var builder = WebApplication.CreateBuilder(args);
// Register depancies for data acess it is good to use add scoped
builder.Services.AddDbContext<AppDbContext>(options =>
   options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection"))
);
builder.Services.AddScoped<IPieRespository, MockPieRepository>();
builder.Services.AddScoped<ICatgeoryRepository, MockCategoryRepository>();
builder.Services.AddScoped<IPieRespository, PieRepository>();
builder.Services.AddScoped<ICatgeoryRepository, CategoryRepository>();

builder.Services.AddControllersWithViews();

var app = builder.Build();

app.UseDeveloperExceptionPage();
app.UseHsts();
app.UseStaticFiles();
app.UseRouting();

// this important:
app.MapControllerRoute(
    name: "default",
    pattern: "{controller=Pie}/{action=List}/{id?}");

var serviceDescriptor = builder.Services.Where(sd => sd.ServiceType.Name.Contains("AppDbContext")).FirstOrDefault();
serviceDescriptor.ServiceType.GetType().

// AppDbContext context = (AppDbContext)builder.Services[0];
DbInitializer.Seed((AppDbContext)serviceDescriptor);
app.Run();

Now I have another static class that is asking for the DbContext.

Here is my class:

namespace BethanyPieShop.Models
{
    public static class DbInitializer
    {
        public static void Seed(AppDbContext context)
        {
            //AppDbContext context = applicationBuilder.ApplicationServices.GetRequiredService<AppDbContext>();

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

            if (!context.Pies.Any())
            {
                context.AddRange
                (
                    new Pie { Name = "Apple Pie", Price = 12.95M, ShortDescription = "Our famous apple pies!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", Category = Categories["Fruit pies"], ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/applepie.jpg", InStock = true, IsPieOfTheWeek = true, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/applepiesmall.jpg", AllergyInformation = "" },
                    new Pie { Name = "Blueberry Cheese Cake", Price = 18.95M, ShortDescription = "You'll love it!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", Category = Categories["Cheese cakes"], ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/blueberrycheesecake.jpg", InStock = true, IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/blueberrycheesecakesmall.jpg", AllergyInformation = "" },
                    new Pie { Name = "Cheese Cake", Price = 18.95M, ShortDescription = "Plain cheese cake. Plain pleasure.", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", Category = Categories["Cheese cakes"], ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cheesecake.jpg", InStock = true, IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cheesecakesmall.jpg", AllergyInformation = "" },
                    new Pie { Name = "Cherry Pie", Price = 15.95M, ShortDescription = "A summer classic!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", Category = Categories["Fruit pies"], ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cherrypie.jpg", InStock = true, IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cherrypiesmall.jpg", AllergyInformation = "" },
                    new Pie { Name = "Christmas Apple Pie", Price = 13.95M, ShortDescription = "Happy holidays with this pie!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", Category = Categories["Seasonal pies"], ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/christmasapplepie.jpg", InStock = true, IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/christmasapplepiesmall.jpg", AllergyInformation = "" },
                    new Pie { Name = "Cranberry Pie", Price = 17.95M, ShortDescription = "A Christmas favorite", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", Category = Categories["Seasonal pies"], ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cranberrypie.jpg", InStock = true, IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cranberrypiesmall.jpg", AllergyInformation = "" },
                    new Pie { Name = "Peach Pie", Price = 15.95M, ShortDescription = "Sweet as peach", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", Category = Categories["Fruit pies"], ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/peachpie.jpg", InStock = false, IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/peachpiesmall.jpg", AllergyInformation = "" },
                    new Pie { Name = "Pumpkin Pie", Price = 12.95M, ShortDescription = "Our Halloween favorite", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", Category = Categories["Seasonal pies"], ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/pumpkinpie.jpg", InStock = true, IsPieOfTheWeek = true, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/pumpkinpiesmall.jpg", AllergyInformation = "" },
                    new Pie { Name = "Rhubarb Pie", Price = 15.95M, ShortDescription = "My God, so sweet!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", Category = Categories["Fruit pies"], ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/rhubarbpie.jpg", InStock = true, IsPieOfTheWeek = true, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/rhubarbpiesmall.jpg", AllergyInformation = "" },
                    new Pie { Name = "Strawberry Pie", Price = 15.95M, ShortDescription = "Our delicious strawberry pie!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", Category = Categories["Fruit pies"], ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/strawberrypie.jpg", InStock = true, IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/strawberrypiesmall.jpg", AllergyInformation = "" },
                    new Pie { Name = "Strawberry Cheese Cake", Price = 18.95M, ShortDescription = "You'll love it!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", Category = Categories["Cheese cakes"], ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/strawberrycheesecake.jpg", InStock = false, IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/strawberrycheesecakesmall.jpg", AllergyInformation = "" }
                );
            }

            context.SaveChanges();

Now in my program class, I am calling

DbInitializer.Seed((AppDbContext)serviceDescriptor);

If I search all my registered services in the builder.

I can find the service descriptor for the DbContext class:

var serviceDescriptor = builder.Services.Where(sd => sd.ServiceType.Name.Contains("AppDbContext")).FirstOrDefault();

It's not clear what happens. You call DbInitializer.Seed((AppDbContext)serviceDescriptor); and does it error out? Whats the problem? — Jeremy Thompson
– Jeremy Thompson, Commented Feb 24, 2022 at 4:36
I need to access the AppDbContext class in the programme class after build @JeremyThompson — user18295516
– user18295516, Commented Feb 24, 2022 at 4:37
That doesn't explain whats happening and we're not here to guess. I can see you need to access the AppDbContext class in the DbInitializer class after build and usually with DI setup it should inject it into the Class. You're passing serviceDescriptor and whats wrong with that, which line fails, what error does it cause? — Jeremy Thompson
– Jeremy Thompson, Commented Feb 24, 2022 at 4:42
DbInitializer.Seed((AppDbContext)serviceDescriptor); in this line it fails, it says can not convert from service descriptor to appDbContext — user18295516
– user18295516, Commented Feb 24, 2022 at 4:49
You need to create a service scope to access scoped services. Which has plenty of duplicate questions / answers. — Jeremy Lakeman
– Jeremy Lakeman, Commented Feb 24, 2022 at 6:31

Jeremy Thompson · Accepted Answer · 2022-02-24 07:02:24Z

1

In my Unit Tests I often need to get Services like you're showing. There's obviously not two classes that contain the name AppDbContext so for some reason its not getting the Service properly. This is how I do it with IWebHostEnvironment, you might try something similar:

public UnitTests()
{
    var builder = WebApplication.CreateBuilder();
    var app = builder.Build();
    _serviceProvider = new DependencyResolverHelper(app);

    env = _serviceProvider.GetService<IWebHostEnvironment>();
    AppDomain.CurrentDomain.SetData("ContentRootPath", env.ContentRootPath);
    AppDomain.CurrentDomain.SetData("WebRootPath", env.WebRootPath);
}

A Dependency Helper Class:

public class DependencyResolverHelper
{
    private readonly WebApplication _webApp;

    public DependencyResolverHelper(WebApplication webApp) => _webApp = webApp;

    private IServiceScope serviceScope;

    public T GetService<T>()
    {
        try
        {
            serviceScope = _webApp.Services.CreateScope();
            var services = serviceScope.ServiceProvider;
            var scopedService = services.GetRequiredService<T>();
            return scopedService;
        }
        catch (Exception e)
        {
            Console.WriteLine(e);
            throw;
        }
    }

    public void DisposeServiceScope()
    {
        if (serviceScope != null) serviceScope.Dispose();
    }
}

}

edited Feb 24, 2022 at 7:02

answered Feb 24, 2022 at 6:03

Jeremy Thompson

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2 Comments

Jeremy Lakeman Over a year ago

You're not managing the lifetime of the service scope? You really should dispose the scope when you are done with it.

Jeremy Thompson Over a year ago

@JeremyLakeman thanks for that tip.. this Unit Testing code could easily end up in PROD!

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