Question

我有3张桌子，

 public class DatabaseInitializer : DropCreateDatabaseIfModelChanges<DatabaseContext>
    {
        protected override void Seed(DatabaseContext context)
        {
            base.Seed(context);

            //
            context.Cities.Add(
        new Cities() { CityId = 1, CityDesc = "Tel Aviv" }
        );
            context.Cities.Add(
    new Cities() { CityId = 2, CityDesc = "Ramat Gan" }

    );

            context.Streets.Add(
                new Streets() { StreetId = 1, CityId = 1, StreetDesc = "Pinkas"}
                );

            context.Streets.Add(
              new Streets() { StreetId = 2, CityId = 2, StreetDesc = "Bialik" }
              );

            context.Parkings.Add(
              new Parkings() { ParkStreetId = 1, ParkCityId = 1, StartDate = "2018-01-17", EndDate = "2018-01-17" }
              );

            context.Parkings.Add(
          new Parkings() { ParkStreetId = 2, ParkCityId = 2, StartDate = "2018-01-17", EndDate = "2018-01-17" }
          );

            context.SaveChanges();
        }
    }

这个想法是 - 城市有很多街道，街道有很多停车场。最终的目标是带来一个包含以下内容的Parkings对象：

[dbo.Parkings.ParkId，dbo.Parkings.ParkStartDate，dbo.Parkings.ParkEndDate，dbo.Cities.CityDesc，dbo.Streets.StreetDesc]

（进入新停车场的表格将包含：StartDate，EndDate，CityDesc，StreetDesc）

我首先尝试使用数据为数据库设定种子：

"exceptionMessage": "The ForeignKeyAttribute on property 'Cities' on type 'BeraleBack.Models.entites+Parkings' is not valid. The foreign key name 'CityId' was not found on the dependent type 'BeraleBack.Models.entites+Parkings'. The Name value should be a comma separated list of foreign key property names.",
  "exceptionType": "System.InvalidOperationException",

但是我收到了这个错误：

{{1}}

我首先要知道，如果我的配置是基于我提供的信息是正确的。第二，我应该如何种下它？

我是一个完整的菜鸟，并没有遇到任何有用的教程..

非常感谢!!

Answer 1

当我更频繁地使用DBFirst时，请耐心等待，但看起来您的实体框架无法找到您的外键属性。

将Parkings与Streets

进行比较

public class Streets
    {
        [Key]
        public int StreetId { get; set; }

        public int CityId { get; set; } //Property which foreign key is assoctiated with
        [Required]
        public string StreetDesc { get; set; }

        [ForeignKey("CityId")]
        public virtual Cities Cities { get; set; }

    }

但是Parkings实体

中没有此属性

public class Parkings
    {
        [Key]
        public int ParkId { get; set; }
        [Required]
        public string StartDate { get; set; }
        [Required]
        public string EndDate { get; set; }  

        public int ParkStreetId { get; set; }

        public int CityId{ get; set; }

        [ForeignKey("CityId")]
        public virtual Cities Cities { get; set; }
    }

实体框架外键＆amp;种子了解

1 个答案: