设置一对一关系

Question

如何在Entity Framework的code-first中使用fluent API正确设置一对一关系？

根模型是Project 类。每个项目都包含一个报价。它还可以选择包含一个客户订单。

历史模型的目的是包含各个非历史行的快照（当添加Project 时，会创建一个新的Project，然后将其复制到一个新的ProjectHistorical 类中，如果它是编辑后，将创建一个新的ProjectHistorical 类，其中填充了编辑后的Project 的数据）。 历史对象应该是AutoMapper 友好的。您可以将历史模型视为一种愚蠢、琐碎和幼稚的解决方法，因为数据库引擎中不支持时态数据库。

使用此配置，我遇到以下困难：

1. CustomerOrders 和 Offers 表及其历史 对应对象生成了一个Project_Id 列。我没找到办法 如何强制使用Id 主键或注释 ProjectId 属性（我更喜欢使用注释过的ProjectId 属性）。
2. ProjectHistoricals 表有 生成CustomerOrder_Id 和Offer_Id 列。我没找到办法 如何强制使用Id 列（请注意，Id 列不是历史表的主键）或注释 CustomerOrderId 和 OfferId 列（在 Project 和 ProjectHistorical类；我更喜欢使用带注释的CustomerOrderId 和OfferId 列）。

我尝试了很多搜索并尝试了更多的东西，但没有达到（我本来）预期的效果。

我有以下型号：

public class Project
{
  public virtual int Id { get; set; }
  // public virtual int OfferId { get; set; }
  public virtual Offer Offer { get; set; }
  // public virtual int? CustomerOrderId { get; set; }
  public virtual CustomerOrder CustomerOrder { get; set; }
}

public class ProjectHistorical
{
  public virtual int LogId { get; set; }
  public virtual int Id { get; set; }
  // public virtual int OfferId { get; set; }
  public virtual Offer Offer { get; set; }
  // public virtual int? CustomerOrderId { get; set; }
  public virtual CustomerOrder CustomerOrder { get; set; }
}

public class CustomerOrder 
{
  public virtual int Id { get; set; }
  // public virtual int ProjectId { get; set; }
  public virtual Project Project { get; set; }
}

public class CustomerOrderHistorical
{
  public virtual int LogId { get; set; }
  public virtual int Id { get; set; }
  // public virtual int ProjectId { get; set; }
  public virtual Project Project { get; set; }
}

public class Offer
{
  public virtual int Id { get; set; }
  // public virtual int ProjectId { get; set; }
  public virtual Project Project { get; set; }
}

public class OfferHistorical
{
  public virtual int LogId { get; set; }
  public virtual int Id { get; set; }
  // public virtual int ProjectId { get; set; }
  public virtual Project Project { get; set; }
}

以及以下 fluent api（主键必须始终命名为 Id，因为所有模型都实现了一个共享接口，而不是由应用程序的通用部分使用）：

modelBuilder.Conventions.Remove<IdKeyDiscoveryConvention>();
modelBuilder.Conventions.Remove<ForeignKeyAssociationMultiplicityConvention>();
modelBuilder.Conventions.Remove<PrimaryKeyNameForeignKeyDiscoveryConvention>();
modelBuilder.Conventions.Remove<OneToOneConstraintIntroductionConvention>();
modelBuilder.Conventions.Remove<TypeNameForeignKeyDiscoveryConvention>();
modelBuilder.Conventions.Remove<AssociationInverseDiscoveryConvention>();
modelBuilder.Conventions.Remove<ManyToManyCascadeDeleteConvention>();
modelBuilder.Conventions.Remove<OneToManyCascadeDeleteConvention>();

modelBuilder.Entity<CustomerOrder>().HasKey(t => t.Id);

modelBuilder.Entity<CustomerOrderHistorical>().HasKey(t => t.LogId);
modelBuilder.Entity<CustomerOrderHistorical>().HasRequired(t => t.Project);

modelBuilder.Entity<Offer>().HasKey(t => t.Id);

modelBuilder.Entity<OfferHistorical>().HasKey(t => t.LogId);
modelBuilder.Entity<OfferHistorical>().HasRequired(t => t.Project);

modelBuilder.Entity<Project>().HasKey(t => t.Id);
modelBuilder.Entity<Project>().HasRequired(t => t.Offer).WithRequiredPrincipal(t => t.Project);
modelBuilder.Entity<Project>().HasOptional(t => t.CustomerOrder).WithRequired(t => t.Project);

modelBuilder.Entity<ProjectHistorical>().HasKey(t => t.LogId);
modelBuilder.Entity<ProjectHistorical>().HasRequired(t => t.Offer);
modelBuilder.Entity<ProjectHistorical>().HasOptional(t => t.CustomerOrder);

这是实体框架将模型编译到数据库的方式：

        CreateTable(
            "dbo.CustomerOrderHistoricals",
            c => new
                {
                    LogId = c.Int(nullable: false, identity: true),
                    Id = c.Int(nullable: false),
                    Project_Id = c.Int(nullable: false),
                })
            .PrimaryKey(t => t.LogId)
            .ForeignKey("dbo.Projects", t => t.Project_Id)
            .Index(t => t.Project_Id);

        CreateTable(
            "dbo.Projects",
            c => new
                {
                    Id = c.Int(nullable: false, identity: true),
                })
            .PrimaryKey(t => t.Id);

        CreateTable(
            "dbo.CustomerOrders",
            c => new
                {
                    Id = c.Int(nullable: false, identity: true),
                    Project_Id = c.Int(nullable: false),
                })
            .PrimaryKey(t => t.Id)
            .ForeignKey("dbo.Projects", t => t.Project_Id)
            .Index(t => t.Project_Id);

        CreateTable(
            "dbo.Offers",
            c => new
                {
                    Id = c.Int(nullable: false, identity: true),
                    Project_Id = c.Int(nullable: false),
                })
            .PrimaryKey(t => t.Id)
            .ForeignKey("dbo.Projects", t => t.Project_Id)
            .Index(t => t.Project_Id);

        CreateTable(
            "dbo.OfferHistoricals",
            c => new
                {
                    LogId = c.Int(nullable: false, identity: true),
                    Id = c.Int(nullable: false),
                    Project_Id = c.Int(nullable: false),
                })
            .PrimaryKey(t => t.LogId)
            .ForeignKey("dbo.Projects", t => t.Project_Id)
            .Index(t => t.Project_Id);

        CreateTable(
            "dbo.ProjectHistoricals",
            c => new
                {
                    LogId = c.Int(nullable: false, identity: true),
                    Id = c.Int(nullable: false),
                    CustomerOrder_Id = c.Int(),
                    Offer_Id = c.Int(nullable: false),
                })
            .PrimaryKey(t => t.LogId)
            .ForeignKey("dbo.CustomerOrders", t => t.CustomerOrder_Id)
            .ForeignKey("dbo.Offers", t => t.Offer_Id)
            .Index(t => t.CustomerOrder_Id)
            .Index(t => t.Offer_Id);

Answer 1

您可以阅读this tutorial 或查看stackoverflow 上的this answer 或MSDN 上的this answer。