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Asp.net – Unable to create a 'DbContext' of type '' while trying to migrate database

I have a Asp.Net project where I try to migrate a Database with a DbContext.
Unfortunately, I get the Error

Unable to create a ‘DbContext’ of type ”. The exception ‘Unable to resolve service for type ‘Microsoft.EntityFrameworkCore.DbContextOptions`1[Bulky.DataAccess.Data.ApplicationDbContext]’ while attempting to activate ‘Bulky.DataAccess.Data.ApplicationDbContext’.’ was thrown while attempting to create an instance.

when I try to migrate the database with the

dotnet ef migrations add AddCategoryToDbAndSeedTable

command

Can you explain to me why it’s not working?
I attached the whole project with a google drive link

Project link: https://drive.google.com/file/d/1hEIv9BeocKmFZRyELYeUZTTtyrIaZbF9/view?usp=sharing

Edit:
And here are the verbose logs:
https://drive.google.com/file/d/1jPweHJc0YsI-Kg_5W6D5cfFQd3n6X8XU/view?usp=sharing

Here is the relevant code:

Program.cs:

using Bulky.DataAccess.Data;
using Microsoft.EntityFrameworkCore;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.
builder.Services.AddControllersWithViews();
builder.Services.AddDbContext<ApplicationDbContext>(options =>
    options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection")));

var app = builder.Build();

// Configure the HTTP request pipeline.
if (!app.Environment.IsDevelopment())
{
    app.UseExceptionHandler("/Home/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.UseAuthorization();

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

app.Run();

ApplicationDbContext.cs:

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

    public DbSet<Category> Categories { get; set; }
    
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<Category>().HasData(
            new Category { Id = 1, Name = "Action", DisplayOrder = 1 },
            new Category { Id = 2, Name = "SciFi", DisplayOrder = 2 },
            new Category { Id = 3, Name = "History", DisplayOrder = 3 }
            );
    }
Tags:

2

Answers


  1. 0

    You need to specify a --project (the project to which the new EF migration should be added) and --startup-project (the project which contains the DB settings) to run the migration against. Without these settings, the Bulky.DataAccess project does not have the DB connection string and the ApplicationDbContext cannot be constructed without dependency injection setup from the BulkyWeb3 project.

    From the same folder as BuklyWeb3.sln, you can run this command:

    dotnet ef migrations add AddInitialMigration --startup-project BulkyWeb3 --project Bulky.DataAccess

    Or, from the same folder as Bulky.DataAccess.csproj, you can run this command:

    dotnet ef migrations add AddInitialMigration --startup-project ..BulkyWeb3

    These commands will create a new EF migration in the new /BulkyWeb3/Bulky.DataAccess/Migrations folder.

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  2. 0

    What you need is an IDesignTimeDbContextFactory<ApplicationDbContext> which will provice a connection string to your ApplicationDbContext while working with the dotnet ef cli tools.

    The connection string can just point to localdb, since dotnet ef migrations add does not connect to the database, it just needs to be able to instantiate your DbContext.

    public class ApplicationDesignTimeDbContextFactory : IDesignTimeDbContextFactory<ApplicationDbContext>
{
    public ApplicationDbContext CreateDbContext(string[] args)
    {
        var optionsBuilder = new DbContextOptionsBuilder<ApplicationDbContext>();
        optionsBuilder.UseSqlServer("Data Source=(localdb)\mssqllocaldb;Initial Catalog=ApplicationDb;integrated security=true;");

        return new ApplicationDbContext(optionsBuilder.Options);
    }
}
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