Model :

using System.ComponentModel.DataAnnotations;
using System;

namespace Data
{
public class User
{
    [Key]
    public int UserID { get; set; }
    public string? Username { get; set; }
    public User()
    {
        
    }
}
}

Context :

using System;
using System.Collections.Generic;
using System.Linq;
using System.Data.SqlClient;
using System.Data;
using System.Threading.Tasks;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Migrations;
using Microsoft.EntityFrameworkCore.Design;

namespace Data
{
public class MyContext : DbContext
{
    public DbSet<User>? Users { get; set; }
    public MyContext(DbContextOptions<MyContext> options) : base(options) { }
    public MyContext()
    {
    }
 }
}

Connection string :

"ConnectionStrings": {
"MyContext" : "data source =(LocalDb)\\MSSQLLocalDB;Initial Catalog=TestVsCodeDB;               Integrated Security=True ",
"providerName" :"System.Data.SqlClient"
}

Slo

I use VS Code and I get this error during migration. I used a similar method in asp.net mvc, but I get this error in asp.net core

CodePudding user response：

Have you added you dbContext in startup or program.cs ? Are you doing the migration in the correct path? it should be something like this:

cd ./project_with_migrations_folder
dotnet ef --startup-project ../my_startup_project_path/ migrations add myMigration01

CodePudding user response：

You must use the default constructor of MyContext.cs. Remove

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

In Program.cs do this

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllers();
string ConnectionString = configuration.GetConnectionString("MyContext");
    services.AddDbContext<ApplicationDbContext>(
        options => options.UseSqlServer(ConnectionString));
}