如何从 Code First 中删除外键？

Question

我有两个模特。自行车和预订。

自行车：

public class Bike
    {
        public int Id { get; set; }
        public BikeType Type { get; set; }
        public BikeGender Gender { get; set; }
        public BikeSize Size { get; set; }
        public string Brand { get; set; }
        public double HourRate { get; set; }
        public double DailyRate { get; set; }
        public virtual Store Store { get; set; }

        [ForeignKey("Store")]
        public int Store_Id { get; set; }
    }

和预订：

public class Reservation
    {
        public int Id { get; set; }
        public DateTime Start { get; set; }
        public DateTime End { get; set; }
        public virtual Customer Customer { get; set; }

        [ForeignKey("Customer")]
        public int Customer_Id { get; set; }

        public virtual List<Bike> Bikes { get; set; }

        public Reservation()
        {
            Bikes = new List<Bike>();
        }
    }

当我从 Code First 创建数据库时，它会在 'Bikes' table 中添加一个名为：'Reservation_Id'.

的列

Click to view image of the problem

当我创建一个新的 Reservation 时出现问题，我选择的自行车从 Reservation 获取 ID 的 'Reservation_Id'。因此，当我尝试删除此预订时，出现错误：

SqlException: The DELETE statement conflicted with the REFERENCE constraint "FK_dbo.Bikes_dbo.Reservations_Reservation_Id". The conflict occurred in database "BikeRental.Model.BikeShopDataModel", table "dbo.Bikes", column 'Reservation_Id'.

我用来删除预订的代码： Click here to view the reservation delete code

如何解决我可以删除预订而不影响唯一密钥的问题？或者如何从 table?

中删除整个唯一键

Answer 1

Bike 和 Reservation 之间存在一对多关系。 EfCore 或 EF 在 Many 侧需要一个 ForeignKey。当你没有在右边定义 ForeignKey 时，EF 会阻止你，因为那个 Reservation 对象依赖于 Bike 对象。你的错误是错误地定义了这种关系。

Bike class 应该是这样的：

public class Bike
    {
        public int Id { get; set; }
        public BikeType Type { get; set; }
        public BikeGender Gender { get; set; }
        public BikeSize Size { get; set; }
        public string Brand { get; set; }
        public double HourRate { get; set; }
        public double DailyRate { get; set; }
        public virtual Store Store { get; set; }
        public List<Reservation> Reservations{get;set;}
        [ForeignKey("Store")]
        public int Store_Id { get; set; }
    }

Reservation class 应该是这样的：

public class Reservation
    {
        public int Id { get; set; }
        public DateTime Start { get; set; }
        public DateTime End { get; set; }
        public virtual Customer Customer { get; set; }

        [ForeignKey("Customer")]
        public int Customer_Id { get; set; }

        public virtual Bike Bike { get; set; }
        [ForeignKey("Bike")]
        public int Bike_Id { get; set; }

    }

如何从 Code First 中删除外键？

How do I remove a Foreign Key from Code First?

c#

asp.net-mvc

localdb