在迁移过程中将ICollection <T>传递到数据库

Question

你好，我正在尝试获取MVC的窍门，并试图将一个本地网站迁移到.NET MVC应用程序中。从JSON文件我用的网站，我想创建的MVC应用程序的数据库模型，但我被困在这个错误：

无法创建 类型的恒定值“ConFusionMVC.Models.Comment ”。在此上下文中仅支持基本类型或枚举 类型。

这是样品JSON：

{ 
     "id": 1, 
     "name": "Zucchipakoda", 
     "image": "images/zucchipakoda.png", 
     "category": "appetizer", 
     "label": "", 
     "price": 1.99, 
     "description": "dish description", 
     "comments": [ 
     { 
      "rating": 5, 
      "comment": "Imagine all the eatables, living in conFusion!", 
      "author": "John Lemon", 
      "date": "2012-10-16T17:57:28.556094Z" 
     }, 
     { 
      "rating": 4, 
      "comment": "Sends anyone to heaven, I wish I could get my mother-in-law to eat it!", 
      "author": "Paul McVites", 
      "date": "2014-09-05T17:57:28.556094Z" 
     }, 
     { 
      "rating": 3, 
      "comment": "Eat it, just eat it!", 
      "author": "Michael Jaikishan", 
      "date": "2015-02-13T17:57:28.556094Z" 
     }, 
     ] 
    } 

所以一般的想法是有2型“菜”和“评论”以1：许多关系，使菜含有评论的ICollection的。论文是类

public class Dish 
    { 
     [Key] 
     public int DishID { get; set; } 
     public string Name { get; set; } 
     public string Image { get; set; } 
     public string Category { get; set; } 
     public string Label { get; set; } 
     public double Price { get; set; } 
     public string Description { get; set; } 
     public virtual ICollection<Comment> Comments { get; set; } 
    } 

public class Comment 
    { 
     [Key] 
     public int CommentID { get; set; } 
     public int Rating { get; set; } 
     public string Comments { get; set; } 
     public string Author { get; set; } 
     public DateTime DatePosted { get; set; } 
    } 

而且我的DbContext类：我使用的代码优先迁移的方法，这就是我遇到的错误

public class ApplicationDbContext : IdentityDbContext<ApplicationUser> 
    { 
     public DbSet<Dish> Dishes { get; set; } 
     public DbSet<Comment> Comments { get; set; } 


     public ApplicationDbContext() 
      : base("DefaultConnection", throwIfV1Schema: false) 
     { 
     } 

     public static ApplicationDbContext Create() 
     { 
      return new ApplicationDbContext(); 
     } 

     protected override void OnModelCreating(DbModelBuilder modelBuilder) 
     { 
      modelBuilder.Entity<Dish>() 
       .HasMany(s => s.Comments); 

      base.OnModelCreating(modelBuilder); 

     } 

。这是我的种子执行：

var comments = new List<Comment> 
      { 
       new Comment { Rating = 5, Author = "John Lemon", 
        Comments = "author comments", 
        DatePosted = DateTime.Parse("2012-10-16T17:57:28.556094Z") 
       }, 
       new Comment { Rating = 4, Author = "Paul McVites", 
        Comments = "author comments", 
        DatePosted = DateTime.Parse("2014-09-05T17:57:28.556094Z") 
       }, 
       new Comment { Rating = 3, Author = "Michael Jaikishan", 
        Comments = "Eat it, just eat it!", DatePosted = DateTime.Parse("2015-02-13T17:57:28.556094Z") 
       }, 

      }; 

      comments.ForEach(p => context.Comments.AddOrUpdate(c => c.CommentID, p)); 
      context.SaveChanges(); 

      var dishes = new List<Dish> 
      { 

       new Dish 
       { 
        Name ="Uthapizza", Image="~/Images/uthapizza.png", Category="Mains", 
        Label ="Hot", Price=4.99, Description="dish comments" , 
        Comments = new List<Comment>() 
        { 
         comments[0],comments[1], comments[2] 
        } 
       }, 
       new Dish 
       { 
        Name="Zucchipakoda", Image="~/Images/zucchipakoda.png", 
        Category="Appetizer", Label="Hot", Price=1.99, Description = "dish comments", 
        Comments = new List<Comment>() 
        { 
         comments[0],comments[1], comments[2] 
        } 
       }, 

      }; 

      dishes.ForEach(s => context.Dishes.AddOrUpdate(p => p.Comments, s)); 
      context.SaveChanges(); 
     } 

如何获得将注释保存到每个单独的菜肴的数据库？请协助

Answer 1

您可以尝试如下所示。

new Dish 
     { 
     Name ="Uthapizza", Image="~/Images/uthapizza.png", Category="Mains", 
     Label ="Hot", Price=4.99, Description="dish comments" , 
     Comments = new List<Comment>() 
       { 
       new Comment { Rating = 5, Author = "John Lemon", 
           Comments = "author comments", 
           DatePosted = DateTime.Parse("2012-10-16T17:57:28.556094Z") 
       }, 
       new Comment { Rating = 4, Author = "Paul McVites", 
          Comments = "author comments", 
          DatePosted = DateTime.Parse("2014-09-05T17:57:28.556094Z") 
       }, 
       new Comment { Rating = 3, Author = "Michael Jaikishan", 
          Comments = "Eat it, just eat it!", DatePosted = DateTime.Parse("2015-02-13T17:57:28.556094Z") 
       }, 

       } 
     },