c# - 错误 OnModelCreating (ModelBuilder)' : no suitable method found to override

Question

在一个新的asp.net core 3.1项目中返回上面的错误信息。我有一个根据 Text 配置的多对多关系

不确定为什么会发生这种情况，但我已将 EntityFrameworkCore 包添加到项目中，所以我不确定为什么会返回此错误。

数据库上下文.cs:

using Microsoft.EntityFrameworkCore;
using Ballista.Models;

namespace Ballista.Data 
{
    public class AnnouncementsContext : DbContext
    {
        public AnnouncementsContext (DbContextOptions<AnnouncementsContext> options)
            : base(options)
        {
        }

        public DbSet<Announcements> Announcements { get; set; }
        public DbSet<AnnouncementTargets> AnnouncementTargets { get; set; }
        public DbSet<TargetGroup> TargetGroup { get; set; }
    }
    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<AnnouncementTargets>()
            .HasKey(at => new { at.AnnouncementID, at.TargetGroupID });

        modelBuilder.Entity<AnnouncementTargets>()
            .HasOne(at => at.Announcement)
            .WithMany(a => a.AnnouncementTargets)
            .HasForeignKey(at => at.AnnouncementID);
        modelBuilder.Entity<AnnouncementTargets>()
            .HasOne(at => at.TargetGroup)
            .WithMany(tg => tg.AnnouncementTargets)
            .HasForeignKey(t => t.TargetGroupID);
        base.OnModelCreating(modelBuilder);
    }

}

AnnouncementModels.cs:

using System;
using System.ComponentModel.DataAnnotations;
using System.Collections.Generic;

namespace Ballista.Models
{
    public class Announcements
    {
        public int ID { get; set; }
        public string Title { get; set; }
        public string SubTitle { get; set; }
        public string Content { get; set; }
        public ICollection<AnnouncementTargets> AnnouncementTargets { get; set; }

    }

    public class TargetGroup
    {
        public int ID { get; set; }
        public string Group { get; set; }
        public ICollection<AnnouncementTargets> AnnouncementTargets { get; set; }
    }

    public class AnnouncementTargets
    {
        public int AnnouncementID { get; set; }
        public Announcements Announcement { get; set; }
        public int TargetGroupID { get; set; }
        public TargetGroup TargetGroup { get; set; }
    }
}

我配置了多对多关系，但我不断收到错误消息 <invalid-global-code>.OnModelCreating(ModelBuilder)': no suitable method found to override

Answer 1

DbContext 有 OnModelCreating(DbModelBuilder) 来覆盖。将函数的定义从 OnModelCreating(ModelBuilder modelBuilder) 更改为 OnModelCreating(DbModelBuilder modelBuilder)

protected override void OnModelCreating(DbModelBuilder modelBuilder)