C# 对象引用未设置为对象的实例（2）

我在asp.net mvc3中使用实体框架，当我尝试向表中添加新记录时，会出现此错误。这是我的密码

namespace CvGenerator.Models
{
    public class LogInEntities:DbContext
    {
        public DbSet LogIn { get; set; }


        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Conventions.Remove<IncludeMetadataConvention>();
            modelBuilder.Entity<LogIn>().ToTable("LogInData");
            base.OnModelCreating(modelBuilder);
        }
    }

}

---

在标记的行中，我得到了一个exeption

请看一看，我只是对您的

登录名
属性和
登录名
的构造函数做了一些更改

希望你现在不会在所提到的线路上受到干扰

namespace CvGenerator.Models
{
    public class LogInEntities:DbContext
    {
        List<DbSet> lgn;
        public LogInEntities()
        {
             lgn = new List<DbSet>();
        }
        public List<DbSet> LogIn { get{return lgn;} set{lgn=value;} }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Conventions.Remove<IncludeMetadataConvention>();
            modelBuilder.Entity<LogIn>().ToTable("LogInData");
            base.OnModelCreating(modelBuilder);
        }
    }

}

在标记的行中，我得到了exeption
请改为尝试DbSet登录

public void LogIn(string email,string nameAndSurname)
{
    LogInEntities logIndb = new LogInEntities();
    LogIn logIn = new LogIn();

    if(ModelState.IsValid)
    {
        logIn.Email = email;
        logIn.NameAndSurname = nameAndSurname;
        ***logIndb.LogIn.Add(logIn);***
        logIndb.SaveChanges();
    }
}

namespace CvGenerator.Models
{
    public class LogInEntities:DbContext
    {
        List<DbSet> lgn;
        public LogInEntities()
        {
             lgn = new List<DbSet>();
        }
        public List<DbSet> LogIn { get{return lgn;} set{lgn=value;} }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            modelBuilder.Conventions.Remove<IncludeMetadataConvention>();
            modelBuilder.Entity<LogIn>().ToTable("LogInData");
            base.OnModelCreating(modelBuilder);
        }
    }

}

public class LogIn
{
    public int LogInId { get; set; }
    public string NameAndSurname { get; set; }
    public string Email { get; set; }
    public virtual ICollection<LogIn> LogInCol { get; set; }
}

public void LogIn(string email,string nameAndSurname)
{
    LogInEntities logIndb = new LogInEntities();
    LogIn logIn = new LogIn();

    if(ModelState.IsValid)
    {
        logIn.Email = email;
        logIn.NameAndSurname = nameAndSurname;
        ***logIndb.LogIn.Add(logIn);***
        logIndb.SaveChanges();
    }
}