Entity Framework Core 无法创建“DbContext”类型的对象。 错误

Question

I am building an n-tier web api with .net 6 using cqrs and mediatr patterns.

But i am getting the following exception when i want to add first migration.

Unable to create an object of type 'WorldCupApiDbContext'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

This is what my solution looks like:

My Program.cs codes:

using System.Reflection;
using MediatR;
using Microsoft.EntityFrameworkCore;
using WorldCupApi.Application.Handler.QueryHandler;
using WorldCupApi.Repository.Entities;

var builder = WebApplication.CreateBuilder(args);

// Add services to the container.

builder.Services.AddControllers();
// Learn more about configuring Swagger/OpenAPI at https://aka.ms/aspnetcore/swashbuckle
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

builder.Services.AddDbContextPool<WorldCupApiDbContext>(options =>
{
    options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection"));
});

builder.Services.AddMediatR(typeof(GetGroupQueryHandler).GetTypeInfo().Assembly);

var app = builder.Build();

// Configure the HTTP request pipeline.
if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();

app.UseAuthorization();

app.MapControllers();

app.Run();

My DbContext codes:

using Microsoft.EntityFrameworkCore;

namespace WorldCupApi.Repository.Entities;

public class WorldCupApiDbContext : DbContext
{
    public WorldCupApiDbContext(DbContextOptions<WorldCupApiDbContext> options) : base(options)
    {
        
    }
    
    //entities
    public DbSet<Group> Groups { get; set; }
    public DbSet<Team> Teams { get; set; }
}

I tried editing the DbContext register as follows but doesn't work.

builder.Services.AddDbContextPool<WorldCupApiDbContext>(options =>
{
    options.UseSqlServer(builder.Configuration.GetConnectionString("DefaultConnection"), 
        b=> b.MigrationsAssembly("WorldCupApi.Repository"));
});

If you need more details, I can send them quickly. Please help me.

Answer 1

I solved the problem. I would like to share with you too.

if you use dotnet-cli just type this in terminal:

dotnet ef migrations add MigrationName -s mainProject -p DbContextProject