C# 实体框架中的多重性

我是实体框架的新手，在尝试首先实现ERD代码时遇到了一些问题。情况如下：

一个产品有一组问题。一个问题组有多个问题，可以属于多个问题组。问卷基本上有一个问题组和一个问题顺序。问题顺序应该保持问题在该问卷中的位置。因为一个问题组可以有多个问题顺序，并且一个问题顺序可以属于多个问题组，所以需要使用问询表

因为我正在尽我最大的努力保持这篇文章的简洁，除非你要求看，否则我不会发布我所有的课程。我创建的实体类如下所示：

public class Question
    {
        [Key]
        public int Id { get; set; }

        [MaxLength(2000)]
        [Required]
        public string Text { get; set; }
        public Answer Answer { get; set; }
        public QuestionType Type { get; set; }
        public ICollection<QuestionAnswerOption> Options { get; set; }
        public ICollection<QuestionOrder> Orders { get; set; }

        [ForeignKey("FollowupQuestion")]
        public int QuestionId { get; set; }
        public virtual Question FollowupQuestion { get; set; }
        [ForeignKey("Questiongroup")]
        public int QuestionGroupId { get; set; }
        public virtual QuestionGroup Questiongroup { get; set; }

    }

public class QuestionOrder
    {
        [Key]
        public int Id { get; set; }

        public int Position { get; set; }

        [ForeignKey("Question")]
        [Required]
        public int QuestionId { get; set; }
        public virtual Question Question { get; set; }
        [ForeignKey("Questionaire")]
        [Required]
        public int QuestionaireId { get; set; }
        public virtual Questionaire Questionaire { get; set; }

    }

  public class Product
    {
        [Key]
        public int Id { get; set; }

        [MaxLength(150)]
        [Required]
        [Index(IsUnique = true)]
        public string Name { get; set; }
        [MaxLength(500)]
        public string Summary { get; set; }
        [MaxLength(500)]
        public string Examples { get; set; }
        public virtual QuestionGroup QuestionGroup { get; set; }
    }

public class QuestionGroup
    {
        [Key]
        public int Id { get; set; }

        public ICollection<Question> Questions { get; set; }

        [ForeignKey("Product")]
        public int ProductId { get; set; }
        public virtual Product Product { get; set; }

    }

 public class Questionaire
    {
        [Key]
        public int Id { get; set; }

        public QuestionGroup Group { get; set; }

        public QuestionOrder Order { get; set; }
    }

我得到的错误如下所示：

QuestionGroup\u Product\u Source:：多重性在关系“QuestionGroup\u Product”中的角色“QuestionGroup\u Product\u Source”中无效。因为依赖角色属性不是键属性，所以依赖角色的多重性上限必须为“*”

QuestionOrder\u Questionaire\u Source:：多重性在关系“QuestionOrder\u Questionaire”中的角色“QuestionOrder\u Questionaire\u Source”中无效。因为依赖角色属性不是键属性，所以依赖角色的多重性上限必须为“*”

QuestionType\u Question\u Source:：多重性在关系“QuestionType\u Question”中的角色“QuestionType\u Question\u Source”中无效。因为依赖角色属性不是键属性，所以依赖角色的多重性上限必须为“*”

我们得出的问题是：

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这里有人知道修复我的表之间关系的方法吗？也许我的ERD也需要一些改进，但我认为问题在于我的代码优先实现缺少一些东西。

这个设计对您来说怎么样

public class Customer
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int CustomerId { get; set; }
    public string CompanyName { get; set; }

    public virtual ICollection<ContactInfo> ContactInfoes { get; set; }
    public virtual ICollection<ProductQuestionaireReport> Reports { get; set; }
}
public class ContactInfo
{
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [Key]
    public int ContactInfoId { get; set; }
    public string Name { get; set; }
    public string Email { get; set; }
    public int Telephone { get; set; }

    [ForeignKey("Customer")]
    public int CustomerId { get; set; }
    public virtual Customer Customer { get; set; }
}
public class ProductQuestionaireReport
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ProductQuestionaireReportId { get; set; }

    [ForeignKey("Product")]
    public int ProductId { get; set; }
    public virtual Product Product { get; set; }

    public virtual QuestionaireResult Result { get; set; }

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

    public bool Haste { get; set; }
    public string Status { get; set; }
    public string Comment { get; set; }
}
public class QuestionaireResult
{
    [Key, ForeignKey("ProductQuestionaireReport")]
    public int ProductQuestionaireReportId { get; set; }

    [ForeignKey("Questionaire")]
    public int QuestionaireId { get; set; }
    public virtual Questionaire Questionaire { get; set; }

    public DateTime SurveyCreated { get; set; }
    public Double Costs { get; set; }
    public Double FunctionPoints { get; set; }

    public virtual ProductQuestionaireReport ProductQuestionaireReport { get; set; }
    public virtual ICollection<QuestionaireAnswer> Answers { get; set; }
}
public class Product
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ProductId { get; set; }
    public string Name { get; set; }
    public string Summary { get; set; }
    public string Examples { get; set; }

    public virtual ICollection<Questionaire> Questionaires { get; set; }
    public virtual ICollection<ProductQuestionaireReport> Reports { get; set; }
}
public class QuestionaireAnswer
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int QuestionaireAnswerId { get; set; }

    [ForeignKey("QuestionaireResult")]
    public int QuestionaireResultId { get; set; }
    public virtual QuestionaireResult QuestionaireResult { get; set; }

    [ForeignKey("QuestionaireQuestion")]
    public int QuestionaireId { get; set; }
    public virtual QuestionaireQuestion QuestionaireQuestion { get; set; }

    [ForeignKey("Answer")]
    public int AnswerId { get; set; }
    public virtual QuestionOption Answer { get; set; }

    public string Text { get; set; }
    public virtual ICollection<string> Files { get; set; }
}
public class Questionaire
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int QuestionaireId { get; set; }
    [ForeignKey("Product")]
    public int ProductId { get; set; }
    public virtual Product Product { get; set; }

    public virtual ICollection<QuestionaireQuestion> QuestionaireQuestions { get; set; }
    public virtual ICollection<QuestionaireResult> Results { get; set; }
}
public class Question
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int QuestionId { get; set; }

    [ForeignKey("ParentQuestion")]
    public int ParentQuestionId { get; set; }
    public virtual Question ParentQuestion { get; set; }

    public virtual QuestionType QuestionType { get; set; }
    public virtual ICollection<QuestionOption> Options { get; set; }
}
public class QuestionType
{
    [Key, ForeignKey("Question")]
    public int QuestionId { get; set; }

    public string Text { get; set; }
    public bool IsOpenQuestion { get; set; }

    public virtual Question Question { get; set; }
}
public class QuestionOption
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int QuestionAnswerOptionId { get; set; }

    [ForeignKey("Question")]
    public int QuestionId { get; set; }
    public string Text { get; set; }

    public virtual Question Question { get; set; }
}
public class QuestionaireQuestion
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int QuestionaireQuestionId { get; set; }

    [ForeignKey("Questionaire")]
    public int QuestionaireId { get; set; }
    public virtual Questionaire Questionaire { get; set; }

    [ForeignKey("Question")]
    public int QuestionId { get; set; }
    public int DisplayOrder { get; set; }

    public virtual Question Question { get; set; }
}

---

检查并反馈给我

您是否有其他实体配置？例如，使用Fluent API？不，我没有。我不知道这是怎么回事。缺少产品和问卷的定义。不是100%确定，但可能是因为FK属性名称与键属性名称不相同。我知道这看起来很愚蠢，但请将有问题的Id重命名为QuestionId，看看是否有任何错误消失。如果是这样，你知道这可能是问题的一部分。至于如何处理FollowupQuestion，我不确定EF是如何处理的。另外，将问题中的Id重命名为QuestionId并没有解决任何问题QuestionGroup包含一组特定于产品的问题。我明白你想说什么了。我想你的意思是产品应该有一个Icollection。但不确定这将如何解决问题。嗨@Flippey。。。什么是…的答案实体？在你的ERD中，你有一个答案表，它是什么？这是一个产品调查的ERD吗？这是一种调查是的。答案实体是一个问题的答案。嗨@Flippey我想你的ERD设计有问题。。。检查答案，谢谢。

modelBuilder.Entity<Customer>().HasMany(c => c.ContactInfoes)
    .WithRequired(i => i.Customer).HasForeignKey(i => i.CustomerId).WillCascadeOnDelete(false);

modelBuilder.Entity<Question>().HasMany(q => q.Options)
    .WithRequired(o => o.Question).HasForeignKey(o => o.QuestionId).WillCascadeOnDelete(false);

modelBuilder.Entity<QuestionaireResult>().HasMany(r => r.Answers)
    .WithRequired(a => a.QuestionaireResult).HasForeignKey(o => o.QuestionaireResultId).WillCascadeOnDelete(false);