c# - 找不到合适的方法来覆盖 OnModelCreating()

Question

当我尝试覆盖 OnModelCreating 时虚函数它说找不到合适的方法来覆盖。我很确定我已经安装了所有必要的 Entity Framework 包

using System;
using System.Collections.Generic;
using System.Data.Entity;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;

namespace MVCOurselves.Models
{
    public class MVCOurselvesContext : IdentityDbContext
    {
        public System.Data.Entity.DbSet<Student> Student { get; set; }
        public System.Data.Entity.DbSet<Grade> Grades { get; set; }

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

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            // configures one-to-many relationship
            modelBuilder.Entity<Student>()
                .HasRequired<Grade>(s => s.Grade)
                .WithMany(g => g.Students)
                .HasForeignKey<int>(s => s.Id);
        }

    }

}

Answer 1

查看您的代码后，您似乎已经从 ASP.NET MVC 升级了您的应用程序。至 ASP.NET Core但它仍然引用 ASP.NET MVC 库。

删除 using System.Data.Entity并替换 DbModelBuilder与 ModelBuilder并重写 one-to-many配置如下:

using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Identity.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore;

namespace MVCOurselves.Models
{
    public class MVCOurselvesContext : IdentityDbContext
    {
        public DbSet<Student> Students { get; set; }
        public DbSet<Grade> Grades { get; set; }

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

        protected override void OnModelCreating(ModelBuilder 
modelBuilder)
        {
            // configures one-to-many relationship
            modelBuilder.Entity<Grades>()
                        .HasMany(g => g.Students)
                        .WithOne(s => s.Grade)
                        .HasForeignKey(s => s.GradeId);
        }

    }

}