[英]How do I map an inherited table with a composite key using Entity Framework code-first?
我有兩個課,像這樣:
public class Customer {
public string Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
}
public class CustomerChange : Customer {
public DateTime ChangedAtUtc { get; set; }
}
我正在嘗試使用Entity Framework代碼優先將它們映射到數據庫架構。 模式應如下所示:
+-------------+
| Customer |
+-------------|
| * Id |
| FirstName |
| LastName |
+-------------+
|
|
/|\
+----------------+
| CustomerChange |
+----------------+
| * Id |
| * ChangedAtUtc |
| FirstName |
| LastName |
+----------------+
因此, Customer
表列出了每一個客戶的最新狀態,每一次客戶的變化,我們UPDATE
Customer表和INSERT
一行到CustomerChange表。 CustomerChange為您提供一段時間內該客戶記錄狀態的完整歷史記錄-請注意,在此模型中,CustomerChanges應該被認為是不變的。
我嘗試在[Key]
.Customer屬性和[CustomerChange.ChangedAtUtc [Key]
屬性上都放置[Key]
屬性,但這沒有用。 我試過顯式重寫OnModelCreating:
modelBuilder.Entity<CustomerChange>().Map(m => {
m.MapInheritedProperties();
m.ToTable("CustomerChanges");
}).HasKey(change => new { change.Id, change.ChangedAtUtc });
但我無法讓EF使用復合鍵(Id,ChangedAtUtc)創建CustomerChanges表
(是的,在此示例中,我依靠id + timestamp是唯一的。這很好。)
我應該如何修飾/覆蓋各種實體框架位以正確創建此表?
我認為這應該有效。 將客戶類別定義為:
//Customer class
public class Customer
{
public int Id { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
//Relationships
public virtual ICollection<CustomerChange> CustomerChanges { get; set; }
}
//Mapping details for Customer
public class CustomerMap : EntityTypeConfiguration<Customer>
{
public CustomerMap()
{
this.HasKey(c => c.Id);
}
}
將CustomerChange定義為:
//CustomerChange class
public class CustomerChange
{
public int Id { get; set; }
public DateTime ChangeDate { get; set; }
public string FirstName { get; set; }
public string LastName { get; set; }
//Relationships
public virtual Customer Customer { get; set; }
}
//Mapping details for CustomerChange class
public class CustomerChangeMap : EntityTypeConfiguration<CustomerChange>
{
public CustomerChangeMap()
{
this.HasKey(c => new { c.Id, c.ChangeDate });
//Relationship mappings
this.HasRequired(cm => cm.Customer)
.WithMany(c => c.CustomerChanges)
.HasForeignKey(cm => cm.Id);
}
}
然后在OnModelCreating中添加映射詳細信息
public override void OnModelCreating()
{
this.Configurations.Add(new CustomerMap());
this.Configurations.Add(new CustomerChangeMap());
}
希望它對您有用。
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