EF Fluent API 一对一关系答案

【问题标题】：EF Fluent API One-to-One relationshipEF Fluent API 一对一关系
【发布时间】：2013-05-05 06:27:31
【问题描述】：

我正在尝试配置可选必需的简单关系，但 EF 似乎没有为正确的迁移搭建脚手架：

public class Applicant
{
    public int Id { get; set; }

    public string   FirstName   { get; set; }
    public string   LastName    { get; set; }
    public int ContactInfoId            { get; set; }
    public string PreferredCultureId    { get; set; }

    public virtual ApplicantContact     Contact             { get; set; }
    public virtual Culture              PreferredCulture    { get; set; }
}




public ApplicantConfiguration()
{
    HasKey(a => a.Id);
    Property(a => a.FirstName).IsRequired().HasMaxLength(50);
    Property(a => a.LastName).IsRequired().HasMaxLength(50);

    HasOptional(a => a.Contact)
        .WithRequired(c => c.Applicant)
        .WillCascadeOnDelete();

    HasOptional(a => a.PreferredCulture)
        .WithMany()
        .HasForeignKey(a => a.PreferredCultureId);
}






CreateTable(
    "Main.Applicants",
    c => new
        {
            Id = c.Int(nullable: false, identity: true),
            FirstName = c.String(nullable: false, maxLength: 50),
            LastName = c.String(nullable: false, maxLength: 50),
            ContactInfoId = c.Int(nullable: false),
            PreferredCultureId = c.String(maxLength: 128),
        })
    .PrimaryKey(t => t.Id)
    .ForeignKey("General._Cultures", t => t.PreferredCultureId)
    .Index(t => t.PreferredCultureId);

为什么 ContactInfoId 不是作为外键生成并且可以为空，因为它是关系的可选部分？

【问题讨论】：

标签： entity-framework entity-framework-4 entity-framework-5

【解决方案1】：

在你的领域类中尝试

public class Applicant
{

    public string   FirstName   { get; set; }
    public string   LastName    { get; set; }

    public virtual ApplicantContact     Contact             { get; set; }
    public virtual Culture              PreferredCulture    { get; set; }
}


public class ContactInfo
{
   // whatever contact info fields you have
}

public class Culture
{
  // culture fields
}

那么在你的上下文中有

 public DbSet<ContactInfo> ContactInfos { get; set; }
 public DbSet<Applicant> Applicants { get; set; }
 public DbSet<Culture> Cultures { get; set; }

如果 Id 字段为 int，则应自动获取。

【讨论】：