连接表中的Code First Fluent API和导航属性

Question

我有四个实体,我想通过代码第一流利的API(我使用的是在databaseanswers.org发现了一个模型)转化为数据库中的表,但我不能确定是如何.我遇到的问题是,SuggestedMenuId正在复合键(MenuCourse和CourseRecipeChoice)中的两个不同表中迁移.

这是我得到的信息:

"在模型生成期间检测到一个或多个验证错误:

\ tSystem.Data.Entity.Edm.EdmAssociationConstraint ::关系约束中的从属角色和主要角色中的属性数必须相同."

这是我在EntityTypeConfiguration类中尝试过的,显然不正确......

public class CourseRecipeChoiceConfiguration : EntityTypeConfiguration<CourseRecipeChoice>
{
    public CourseRecipeChoiceConfiguration()
    {
        HasKey(crc => new { crc.Id});
        HasRequired(r => r.Recipe).WithMany(crc => crc.CourseRecipeChoices).HasForeignKey(crc => crc.RecipeId);
        HasRequired(m => m.MenuCourse).WithMany(crc => crc.CourseRecipeChoices).HasForeignKey(crc => crc.MenuCourseId);
        HasRequired(m => m.MenuCourse).WithMany(crc => crc.CourseRecipeChoices).HasForeignKey(crc => crc.SuggestedMenu_MenuCourseId);
    }
}

导航属性的正确语法是什么,以及CourseRecipeChoice连接表的流畅api语法的正确语法是什么？

public class SuggestedMenu
{
    public int SuggestedMenuId { get; set; }

    public virtual ICollection<MenuCourse> MenuCourses { get; set; }
}

public class MenuCourse
{
    public int Id { get; set; }
    public int SuggestedMenuId { get; set; }

    public SuggestedMenu SuggestedMenu { get; set; }
    public virtual ICollection<CourseRecipeChoice> CourseRecipeChoices { get; set; }
}

public class CourseRecipeChoice
{
    public int SuggestedMenuId { get; set; }
    public int MenuCourseId { get; set; }
    public int Id { get; set; }
    public int RecipeId { get; set; }

    //How do I represent the navigation properties in this class? 

}

public class Recipe
{
    public int RecipeId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }

    public ICollection<CourseRecipeChoice> CourseRecipeChoices { get; set; }
}

钥匙如下:

• SuggestedMenu(同上)
• MenuCourse(Id,SuggestedMenuId)
• CourseRecipeChoice(Id,SuggestedMenuId,MenuCourseId,RecipeId) //这实际上是我感到困惑的地方,因为根据模型,SuggestedMenuId是在SuggestedMenu中的PK和在MenuCourse和CourseRecipeChoice中的PF(这可能只是糟糕的设计吗？)
• 配方(RecipeId)

Answer 1

......基于手头的信息(关键,关系并不完全清楚),
这是最复杂的场景,应该涵盖你的想法......

public class SuggestedMenu
{
    public int SuggestedMenuId { get; set; }
    public string Description { get; set; }
    public virtual ICollection<MenuCourse> MenuCourses { get; set; }
    // public virtual ICollection<CourseRecipeChoice> CourseRecipeChoices { get; set; }
}
public class MenuCourse
{
    public int MenuCourseId { get; set; }
    public int SuggestedMenuId { get; set; }
    public SuggestedMenu SuggestedMenu { get; set; }
    public virtual ICollection<CourseRecipeChoice> CourseRecipeChoices { get; set; }
}
public class CourseRecipeChoice
{
    public int CourseRecipeChoiceId { get; set; }
    public int MenuCourseId { get; set; }
    public int SuggestedMenuId { get; set; }
    public int RecipeId { get; set; }
    // no virtuals if required, non-optional 
    public Recipe Recipe { get; set; }
    public MenuCourse MenuCourse { get; set; }
    // public SuggestedMenu SuggestedMenu { get; set; }
}
public class Recipe
{
    public int RecipeId { get; set; }
    public string Name { get; set; }
    public string Description { get; set; }
    public virtual ICollection<CourseRecipeChoice> CourseRecipeChoices { get; set; }
}

......并且OnModelCreating(我更喜欢在那里完成所有配置,虽然它是相同的)...

modelBuilder.Entity<CourseRecipeChoice>()
    .HasKey(crc => new { crc.CourseRecipeChoiceId, crc.SuggestedMenuId, crc.MenuCourseId, crc.RecipeId });

modelBuilder.Entity<CourseRecipeChoice>()
    .HasRequired(r => r.Recipe)
    .WithMany(crc => crc.CourseRecipeChoices)
    .HasForeignKey(crc => crc.RecipeId)
    .WillCascadeOnDelete(false);

modelBuilder.Entity<CourseRecipeChoice>()
    .HasRequired(m => m.MenuCourse)
    .WithMany(crc => crc.CourseRecipeChoices)
    .HasForeignKey(crc => new { crc.MenuCourseId, crc.SuggestedMenuId })
    .WillCascadeOnDelete(false);

modelBuilder.Entity<SuggestedMenu>()
    .HasKey(crc => crc.SuggestedMenuId );

modelBuilder.Entity<MenuCourse>()
    .HasKey(crc => new { crc.MenuCourseId, crc.SuggestedMenuId });

modelBuilder.Entity<MenuCourse>()
    .HasRequired(m => m.SuggestedMenu)
    .WithMany(crc => crc.MenuCourses)
    .HasForeignKey(crc => crc.SuggestedMenuId)
    .WillCascadeOnDelete(false);

modelBuilder.Entity<Recipe>()
    .HasKey(crc => crc.RecipeId );

......并测试例如...

        using (var db = new YourDbContext())
        {
            SuggestedMenu suggestedmenu = new SuggestedMenu { Description = "suggested menu" };
            var menucourse = new MenuCourse { MenuCourseId = 2, SuggestedMenu = suggestedmenu };
            var recipe = new Recipe { Name = "My recipe", Description = "recipe desc" };
            var crc = new CourseRecipeChoice { CourseRecipeChoiceId = 2, MenuCourse = menucourse, Recipe = recipe, };
            db.CourseRecipeChoices.Add(crc);
            int recordsAffected = db.SaveChanges();
            foreach (var crcs in db.CourseRecipeChoices.Include(c => c.MenuCourse).Include(c => c.Recipe))
            {
                Console.WriteLine("{0}, {1}, {2}, {3}", crcs.MenuCourse.MenuCourseId, crcs.MenuCourse.SuggestedMenuId, crcs.Recipe.Name, crcs.Recipe.Description);
            }
        }