Question

我正在创建一个EF Code-First MVC应用程序。当我第一次开始时，我首先使用我知道需要的表格创建了数据库。现在我遇到了需要添加另一个表的情况。在过去，我通常会使用EF Database-First，只需在SSMS中创建表并更新我的EDMX，但我想扩展我的知识并开始执行Code-First项目。

因此，我需要创建的表名为Event，该表将链接到另一个已创建的表...名为ApplicantInformation。

关系是1个事件可以包含许多申请人信息 - Event 1 ... * ApplicantInformation。

以下是我创建Event课程的方法：

public class Event
{
    [Key]
    public int Id { get; set; }
    public string EventName { get; set; }
    public bool Active { get; set; }
}

这是我的ApplicantInformation课程：

[Table("ApplicantInformation")]
public partial class ApplicantInformation
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public ApplicantInformation()
    {
        Events = new HashSet<Event>();
    }
    public int ID { get; set; }

    public string FirstName { get; set; }

    public string LastName { get; set; }

    public int City { get; set; }

    public int State { get; set; }
    public string EmailAddress { get; set; }

    public bool Active { get; set; }
    public DateTime DateEntered { get; set; }
    public int EventId { get; set; }

    [ForeignKey("EventId")]
    public Event Event { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<Event> Events { get; set; }
}

当我add-migration时，我看到了这一点：

    public override void Up()
    {
        CreateTable(
            "dbo.Events",
            c => new
                {
                    Id = c.Int(nullable: false, identity: true),
                    EventName = c.String(),
                    Active = c.Boolean(nullable: false),
                    ApplicantInformation_ID = c.Int(), // where does this come from?
                })
            .PrimaryKey(t => t.Id)
            .ForeignKey("dbo.ApplicantInformation", t => t.ApplicantInformation_ID) // where did ApplicantInformation_ID come from?
            .Index(t => t.ApplicantInformation_ID); // again, where did this property come from?

        AddColumn("dbo.ApplicantInformation", "EventId", c => c.Int(nullable: false));
        CreateIndex("dbo.ApplicantInformation", "EventId");
        AddForeignKey("dbo.ApplicantInformation", "EventId", "dbo.Events", "Id", cascadeDelete: true);
        DropColumn("dbo.ApplicantInformation", "CareerEvent");
    }

我的问题（如果您没有阅读评论），ApplicantInformation_ID来自哪里？我显然没有把这个属性放在我的Event课程中？

感谢任何帮助。

更新

所以我可以摆脱我ICollection<Event>课程中的ApplicantInformation和构造函数，它仍然是一对多的关系？

public class Event
{
    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2214:DoNotCallOverridableMethodsInConstructors")]
    public Event()
    {
        ApplicantInformations = new HashSet<ApplicantInformation>();
    }

    [Key]
    public int Id { get; set; }
    public string EventName { get; set; }
    public bool Active { get; set; }

    [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Usage", "CA2227:CollectionPropertiesShouldBeReadOnly")]
    public virtual ICollection<ApplicantInformation> ApplicantInformations { get; set; }
}

[Table("ApplicantInformation")]
public partial class ApplicantInformation
{
    public int ID { get; set; }

    public string FirstName { get; set; }

    public string LastName { get; set; }

    public int City { get; set; }

    public int State { get; set; }
    public string EmailAddress { get; set; }

    public bool Active { get; set; }
    public DateTime DateEntered { get; set; }
    public int EventId { get; set; }

    [ForeignKey("EventId")]
    public Event Event { get; set; }
}

迁移：

    public override void Up()
    {
        CreateTable(
            "dbo.Events",
            c => new
                {
                    Id = c.Int(nullable: false, identity: true),
                    EventName = c.String(),
                    Active = c.Boolean(nullable: false),
                })
            .PrimaryKey(t => t.Id);

        AddColumn("dbo.ApplicantInformation", "EventId", c => c.Int(nullable: false));
        CreateIndex("dbo.ApplicantInformation", "EventId");
        AddForeignKey("dbo.ApplicantInformation", "EventId", "dbo.Events", "Id", cascadeDelete: true);
        DropColumn("dbo.ApplicantInformation", "CareerEvent");
    }

Answer 1

Per Ivan在评论部分：

我理解，但是你可能把错误的收藏放在了错误的地方。规则很简单 - 您将集合导航属性放在一侧，并在多方面引用导航属性。你描述所需关系的方式，该集合应该是公共ICollection申请人{get;组;在Event类中。

这正是我的问题。

关于创建新表EF代码的困惑 - 首先是一对多

1 个答案: