Generating CRUD pages in ASP.NET 6 Razor Pages ends with an error "Unable to resolve service for type DbContextOptions"

Question

I want to generate CRUD pages for my db models, but I get an error.

What I've done:

1. Created a default ASP.NET Core Web App (Razor Pages) with Individual Account (Identity)
2. Added and configured InMemory package as a DB provider
3. Added a 'Student' model + attached a proper DbSet<> to the context
4. Generated pages for the model (Add Razor Page -> Razor Page using EF (CRUD) -> Model: Student, Data context class: ApplicationDbContext)
5. Works great

but as soon as I split my solution into 3 projects: Test.App, Test.Common, Test.Infrastructure it doesn't work anymore, outputting the error:

Any ideas why that is happening? When my context class is in the main project it suddenly works again.

The code ( https://github.com/RawMajkel/Test ):

Program.cs

using Microsoft.AspNetCore.Identity;
using Microsoft.EntityFrameworkCore;
using Tests.App.Infrastructure.Data;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
var connectionString = builder.Configuration.GetConnectionString("DefaultConnection");
builder.Services.AddDbContext<ApplicationDbContext>(options =>
    options.UseInMemoryDatabase(databaseName: "testDatabase"));
builder.Services.AddDatabaseDeveloperPageExceptionFilter();

builder.Services.AddDefaultIdentity<IdentityUser>(options => options.SignIn.RequireConfirmedAccount = true)
    .AddEntityFrameworkStores<ApplicationDbContext>();
builder.Services.AddRazorPages();

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseMigrationsEndPoint();
}
else
{
    app.UseExceptionHandler("/Error");
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
}

app.UseHttpsRedirection();
app.UseStaticFiles();

app.UseRouting();

app.UseAuthentication();
app.UseAuthorization();

app.MapRazorPages();

app.Run();

Student.cs

using System.ComponentModel.DataAnnotations;

namespace Tests.Common;

public class Student
{
    [Key]
    public string Id { get; set; }
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public DateTime DateOfBirth { get; set; }
    public int Age { get; set; }
}

ApplicationDbContext.cs

using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;
using Tests.Common;

namespace Tests.App.Infrastructure.Data;

public class ApplicationDbContext : IdentityDbContext
{
    public DbSet<Student> Students { get; set; }

    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options)
        : base(options)
    {
    }
}

I've also tried changing public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options): base(options)

to

public ApplicationDbContext(DbContextOptions options): base(options)

but it didn't work either.

Have anyone had this problem before? Thanks for your help

Answer 1

Had this issue and to fix it I had to configure the provider in the DbContext class itself (which was not part of the main api entrypoint csproj)

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    // needed for local scafolding of razor views
    if (!optionsBuilder.IsConfigured)
    {
        optionsBuilder.UseNpgsql("mongodb://localhost:27017/ssl=false");
        // or other provider... like optionsBuilder.UseSqlServer("....");
    }
}

There are probably other ways around it but this worked for me. The downside is that you need to install the provider package on the csproj where the DbContext lives.