c# - 无法使用 DbContext 实体框架核心 SaveChanges()

Question

我对 EF 核心比较陌生，所以对我来说很简单。

我正在尝试使用 Entity Framework Core 使用数据库优先方法（因为代码优先也不起作用）创建应用程序。我已经成功地使用 EF Core 对所有模型进行了逆向工程，但是在尝试使用 my 向数据库添加新项目时DbContext，我收到了一个视图嵌套异常消息。我的应用程序使用两个多对多关系。

我能够将单个项目添加到数据库中，将项目添加到连接表中会出现问题

错误发生后

ctx.Usergorups.Add(newusergroup)

在

ctx.SaveChanges();

以及以下所有Add()声明：

Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure<System.IServiceProvider>.Instance '((Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure<System.IServiceProvider>)ctx.Usergroups).Instance' 引发了“System.NotImplementedException”System.IServiceProvider 类型的异常{System.NotImplementedException}

发现错误发生的地方：

private void Create_Group(object sender, RoutedEventArgs e)
{
    string groupname = this.namebox.Text;

    if (groupname.Equals("Enter user friendly name") || (groupname.Equals("")))
    {
        MessageBox.Show("The group name cannot be the default. Enter something something descriptive");
        return;
    }
    else
    {
        try
        {
            List<UserUserGroup> usergroups = new List<UserUserGroup>();
            List<AccessGroupUserGroup> Accessgroupers = new List<AccessGroupUserGroup>();
            Usergroups newusergroup = new Usergroups()
                {
                    Name = groupname
                };

            var ctx = new FMS_SIRContext();

            ctx.Usergroups.Add(newusergroup);
            ctx.SaveChanges();

            foreach (Users u in this.members.Where(u => u != null))
            {
                usergroups.Add(new UserUserGroup()
                    {
                        UserId = u.Id,
                        User = u,
                        UserGroupId = newusergroup.Id,
                        UserGroup = newusergroup
                    });
            }

            ctx.UserUserGroup.AddRange(usergroups);

            foreach (Accessgroups a in this.acceessGroups.Where(a => a != null))
            {
                Accessgroupers.Add(new AccessGroupUserGroup()
                    {
                        AccessGroup = a,
                        AccessGroupId = a.Id,
                        UserGroup = newusergroup,
                        UserGroupId = newusergroup.Id
                    });
            }

            ctx.AccessGroupUserGroup.AddRange(Accessgroupers);
            ctx.SaveChanges();

            this.Close();
        }
        catch (Exception s)
        {
            MessageBox.Show(s.Data.ToString());
        }
    }
}

我的DbContext班级：

public partial class FMS_SIRContext : DbContext
{
    public FMS_SIRContext()
    {
    }

    public FMS_SIRContext(DbContextOptions<FMS_SIRContext> options)
        : base(options)
    {
        this.ChangeTracker.LazyLoadingEnabled = false;
    }

    public virtual DbSet<AccessGroupUserGroup> AccessGroupUserGroup { get; set; }
    public virtual DbSet<Accessgroups> Accessgroups { get; set; }
    public virtual DbSet<UserUserGroup> UserUserGroup { get; set; }
    public virtual DbSet<Usergroups> Usergroups { get; set; }
    public virtual DbSet<Users> Users { get; set; }

    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
    {
        if (!optionsBuilder.IsConfigured)
        {
            optionsBuilder.UseSqlServer("Data Source=az18w7413;Initial Catalog=****;Persist Security Info=True;User ID=******;Password=******;");
        }
    }

    protected override void OnModelCreating(ModelBuilder modelBuilder)
    {
        modelBuilder.Entity<AccessGroupUserGroup>(entity =>
        {
            entity.HasKey(e => new { e.AccessGroupId, e.UserGroupId });

            entity.ToTable("AccessGroupUserGroup", "asps");
            entity.HasIndex(e => e.UserGroupId);

            entity.Property(e => e.AccessGroupId).HasColumnName("AccessGroupID");
            entity.Property(e => e.UserGroupId).HasColumnName("UserGroupID");

            entity.HasOne(d => d.AccessGroup)
                .WithMany(p => p.AccessGroupUserGroup)
                .HasForeignKey(d => d.AccessGroupId);

            entity.HasOne(d => d.UserGroup)
                .WithMany(p => p.AccessGroupUserGroup)
                .HasForeignKey(d => d.UserGroupId);
        });

        modelBuilder.Entity<Accessgroups>(entity =>
        {
            entity.ToTable("accessgroups", "asps");

            entity.Property(e => e.Id).HasColumnName("ID");
            entity.Property(e => e.Itname).HasColumnName("ITNAME");
            entity.Property(e => e.Name).HasColumnName("NAME");
            entity.Property(e => e.Permission).HasColumnName("PERMISSION");
        });

        modelBuilder.Entity<UserUserGroup>(entity =>
        {
            entity.HasKey(e => new { e.UserId, e.UserGroupId });

            entity.ToTable("UserUserGroup", "asps");
            entity.HasIndex(e => e.UserGroupId);

            entity.Property(e => e.UserId).HasColumnName("UserID");
            entity.Property(e => e.UserGroupId).HasColumnName("UserGroupID");

            entity.HasOne(d => d.UserGroup)
                .WithMany(p => p.UserUserGroup)
                .HasForeignKey(d => d.UserGroupId);

            entity.HasOne(d => d.User)
                .WithMany(p => p.UserUserGroup)
                .HasForeignKey(d => d.UserId)
                .OnDelete(DeleteBehavior.ClientSetNull)
                .HasConstraintName("FK_UserUserGroup_User");
        });

        modelBuilder.Entity<Usergroups>(entity =>
        {
            entity.ToTable("usergroups", "asps");

            entity.Property(e => e.Id).HasColumnName("ID");
            entity.Property(e => e.Name).HasColumnName("NAME");
        });

        modelBuilder.Entity<Users>(entity =>
        {
            entity.ToTable("Users", "asps");

            entity.HasIndex(e => e.Eid)
                .HasName("IX_EID")
                .IsUnique();

            entity.HasIndex(e => e.Id)
                .HasName("IX_ID");

            entity.Property(e => e.Id).HasColumnName("ID");
            entity.Property(e => e.Eid)
                .HasColumnName("EID")
                .HasMaxLength(50);
            entity.Property(e => e.FirstName).HasMaxLength(100);
            entity.Property(e => e.LastName).HasMaxLength(100);
            entity.Property(e => e.LocationId).HasColumnName("LocationID");
            entity.Property(e => e.Mail).HasMaxLength(200);
        });

        OnModelCreatingPartial(modelBuilder);
    }

    partial void OnModelCreatingPartial(ModelBuilder modelBuilder);
}

标签： c#sql-serverwpfentity-framework-core

Answer 1

我终于想通了（8小时后）。这不是依赖注入问题，而是 ID 分配错误。我分配了用户、用户组、访问组和用户组的 ID，并分配了对象，因此从默认构造函数中将 ID 设为 0。

private void Create_Group(object sender, RoutedEventArgs e)
        {
            string groupname = this.namebox.Text;
            if (groupname.Equals("Enter user friendly name") || (groupname.Equals("")))
            {
                MessageBox.Show("The group name cannot be the default. Enter something something descriptive");
                return;
            }
            else
            {
                try
                {
                    List<UserUserGroup> usergroups = new List<UserUserGroup>();
                    List<AccessGroupUserGroup> Accessgroupers = new List<AccessGroupUserGroup>();
                    Usergroups newusergroup = new Usergroups()
                    {
                        Name = groupname
                    };
                    FMS_SIRContext ctx = new FMS_SIRContext();
                    ctx.Usergroups.Add(newusergroup);
                    ctx.SaveChanges();
                    foreach (Users u in members.Where(u => u != null))
                    {
                        usergroups.Add(new UserUserGroup()
                        {
                           UserId = u.Id,
                            //User = u,
                            UserGroupId = newusergroup.Id,
                            //UserGroup = newusergroup
                        });
                    }
                    //ctx.Usergroups.Add(newusergroup);
                    ctx.AddRange(usergroups);
                    foreach (Accessgroups a in this.acceessGroups.Where(a => a != null))
                    {
                        Accessgroupers.Add(new AccessGroupUserGroup()
                        {
                            //AccessGroup = a,
                            AccessGroupId = a.Id,
                            //UserGroup = newusergroup,
                            UserGroupId = newusergroup.Id
                        });
                    }
                    ctx.AddRange(Accessgroupers);
                    ctx.SaveChanges();
                    this.Close();
                }
                catch (Exception s)
                {
                    MessageBox.Show(s.Data.ToString());
                }
            }

        }