我正在开发一个网络应用程序和服务，专门从事带有菜单和预订的餐饮活动。我正在使用种子数据构建数据库，但是当我尝试进行初始创建时出现错误。
错误是：
无法添加实体类型“MenuFoodItem”的种子实体，因为没有为所需属性“FoodItemId1”提供值。
我的代码采用 C# 编写，分为 5 个类：
FoodBooking、FoodItem、Menu、MenuFoodItem 和 CateringDbContext。
这是我每个班级的代码：
餐饮DbContext：
using Microsoft.EntityFrameworkCore;
using static System.Net.Mime.MediaTypeNames;
namespace ThAmCo.Catering.Data
{
public class CateringDbContext : DbContext
{
// Notes
// - DbSet defines the database table.
// - the class name is defined as part of the data model
// - the instance/object name is normally plural
// - by default, the instance name will become the table name
public DbSet<Menu> Menus { get; set; }
public DbSet<FoodItem> FoodItems { get; set; }
public DbSet<MenuFoodItem> MenuFoodItems { get; set; }
public DbSet<FoodBooking> FoodBookings { get; set; }
private string DbPath { get; set; } = string.Empty;
// Constructor to set-up the database path & name
public CateringDbContext()
{
var folder = Environment.SpecialFolder.MyDocuments;
var path = Environment.GetFolderPath(folder);
DbPath = Path.Join(path, "ThAmCo.Catering.db");
}
// OnConfiguring to specify that the SQLite database engine will be used
protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
base.OnConfiguring(optionsBuilder);
optionsBuilder.UseSqlite($"Data Source={DbPath}");
}
protected override void OnModelCreating(ModelBuilder builder)
{
base.OnModelCreating(builder);
builder.Entity<MenuFoodItem>()
.HasKey(ms => new { ms.MenuId, ms.FoodItemId });
builder.Entity<Menu>()
.HasMany(m => m.MenuFoodItems)
.WithOne(fi => fi.Menu)
.HasForeignKey(tr => tr.FoodItemId)
.OnDelete(DeleteBehavior.Restrict);
builder.Entity<FoodItem>()
.HasMany(m => m.MenuFoodItems)
.WithOne(fi => fi.FoodItem)
.OnDelete(DeleteBehavior.Restrict);
// Seed/Test data to be added here
builder.Entity<Menu>().HasData(
new Menu { MenuId = 1, MenuName = "Pasta" },
new Menu { MenuId = 2, MenuName = "Pizza" },
new Menu { MenuId = 3, MenuName = "Pies" },
new Menu { MenuId = 4, MenuName = "Carvery" },
new Menu { MenuId = 5, MenuName = "Desert" }
);
builder.Entity<FoodItem>().HasData(
new FoodItem { FoodItemId = 1, Description = "Tuna Pasta Bake", UnitPrice = 9.99F },
new FoodItem { FoodItemId = 2, Description = "Four Cheese Pizza", UnitPrice = 10.99F },
new FoodItem { FoodItemId = 3, Description = "Chicken and Leak Pie", UnitPrice = 5.65F },
new FoodItem { FoodItemId = 4, Description = "Usual Sunday Carvery", UnitPrice = 12.99F },
new FoodItem { FoodItemId = 5, Description = "Ice Cream with melted Cookies", UnitPrice = 6.99F }
);
builder.Entity<MenuFoodItem>().HasData(
new MenuFoodItem { MenuId = 1, FoodItemId = 1 },
new MenuFoodItem { MenuId = 2, FoodItemId = 2 },
new MenuFoodItem { MenuId = 3, FoodItemId = 3 },
new MenuFoodItem { MenuId = 4, FoodItemId = 4 },
new MenuFoodItem { MenuId = 5, FoodItemId = 5 }
);
builder.Entity<FoodBooking>().HasData(
new FoodBooking { FoodBookingId = 1, ClientReferenceId = 1, NumberOfGuests = 1, MenuId = 1 },
new FoodBooking { FoodBookingId = 2, ClientReferenceId = 2, NumberOfGuests = 2, MenuId = 2 },
new FoodBooking { FoodBookingId = 3, ClientReferenceId = 3, NumberOfGuests = 3, MenuId = 3 },
new FoodBooking { FoodBookingId = 4, ClientReferenceId = 4, NumberOfGuests = 4, MenuId = 4 },
new FoodBooking { FoodBookingId = 5, ClientReferenceId = 5, NumberOfGuests = 5, MenuId = 5 }
);
}
}
}
餐饮预订：
using System.ComponentModel.DataAnnotations;
namespace ThAmCo.Catering.Data
{
public class FoodBooking
{
[Required]
public int FoodBookingId { get; set; }
public int ClientReferenceId { get; set; }
public int NumberOfGuests { get; set; }
public int MenuId { get; set; }
//Placeholder for link to FoodItem
public FoodItem? FoodItem { get; set; }
}
}
食品项目：
using System.ComponentModel.DataAnnotations;
namespace ThAmCo.Catering.Data
{
public class FoodItem
{
[Key]
public int FoodItemId { get; set; }
[MaxLength(50)]
public string Description { get; set; } = null!;
public float UnitPrice { get; set; }
// Placeholder for List of MenuFoodItem
public List<MenuFoodItem> MenuFoodItems { get; set; }
// Placeholder for List of FoodBooking
public List<FoodBooking> FoodBookings { get; set; }
}
}
菜单：
using System.ComponentModel.DataAnnotations;
namespace ThAmCo.Catering.Data
{
public class Menu
{
[Key]
[MaxLength(15)]
public int MenuId { get; set; }
[MaxLength(50)]
public string MenuName { get; set; } = null!;
//Placeholder for List of MenuFoodItem
public List<MenuFoodItem> MenuFoodItems { get; set; }
}
}
菜单食品项目：
using System.ComponentModel.DataAnnotations;
namespace ThAmCo.Catering.Data
{
public class MenuFoodItem
{
[Required]
public int MenuId { get; set; }
[Required]
[MaxLength(15)]
public int FoodItemId { get; set; }
//Placeholder for link to FoodItem
public FoodItem? FoodItem { get; set; }
//Placeholder for link to Menu
public Menu? Menu { get; set; }
}
}
我相信我的人际关系在某个地方出了问题，但不能 100% 确定是哪一部分。
提前谢谢您。
问题可能在于使用
[MaxLength(15)]FoodItemIdusing System.ComponentModel.DataAnnotations;
namespace ThAmCo.Catering.Data
{
public class MenuFoodItem
{
[Required]
public int MenuId { get; set; }
[Required]
public int FoodItemId { get; set; }
public FoodItem? FoodItem { get; set; }
public Menu? Menu { get; set; }
}
}
您应该对 Menu 类执行相同的操作。
namespace ThAmCo.Catering.Data
{
public class Menu
{
[Key]
public int MenuId { get; set; }
[MaxLength(50)]
public string MenuName { get; set; } = null!;
//Placeholder for List of MenuFoodItem
public List<MenuFoodItem> MenuFoodItems { get; set; }
}
}
如果您确实想使用对整数有效的最大值，则可以对整数使用
[MaxValue()]