如何在MVC模型上获取新生成的标识

Question

我有具有多个实体的模型。例如，我有一个order，它有CustomerId到外键。在模型中，我有一些来自order的字段和customer实体的一些字段。当我保存新记录时，我想首先保存customer，获取新生成的身份值并将其放到order表中。如何实现这一目标？我可以通过从customer表中获得MAX(ID)来实现，但我确信有更好的方法来处理这个问题。

这是我的控制器方法：

public ActionResult Create(OrderModels model, FormCollection form) 
{ 
    try 
    { 
     Customer customer = new Customer() { FirstName = model.FirstName, MiddleName = model.MiddleName, SecondName = model.SecondName, Email = model.Email, PhoneNbr = model.PhoneNbr }; 
     int orderSource = Int32.Parse(form["OrderSourceList"]); 
     int paymentType = Int32.Parse(form["PaymentTypeList"]); 
     string warehouseGuid = form["Warehouses"]; 
     ProductLogic productLogic = new ProductLogic(); 
     Product product = productLogic.GetProductByArticle(model.Article); 
     DateTime now = DateTime.Now; 

     SalesOrder salesOrder = new SalesOrder() 
     { 
      OrderNbr = model.OrderNbr, 
      OrderSourceId = orderSource, 
      NpWarehouseRef = new Guid(warehouseGuid), 
      TTN = model.TTN, 
      OrderStatusId = 1, 
      PaymentTypeId = paymentType, 
      OrderDate = DateTime.Now 
     }; 
     using (AccountingRepository repository = new AccountingRepository()) 
     { 

      repository.AddOrUpdate<Customer>(customer); 
      repository.AddOrUpdate<SalesOrder>(salesOrder); 
     } 
     return RedirectToAction("Index"); 
    } 
    catch (Exception e) 
    { 
     return View(); 
    } 
} 

AccountingRepository有dispose方法

public void Dispose() 
{ 
    if (_context != null) 
    { 
     _context.SaveChanges(); 
     _context.Dispose(); 
    } 
} 

我Order类：使用系统

; using System.ComponentModel.DataAnnotations; using System.Collections.Generic; using System.ComponentModel.DataAnnotations.Schema; using System.Data.Entity.ModelConfiguration;

namespace Accounting.Entity 
{ 
    [Table("SalesOrder", Schema = "dbo")] 
    public class SalesOrder 
    { 
     [Key] 
     [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 
     public int? Id { get; set; } 

... 
     public int? CustomerId { get; set; } 

... 
     public virtual Customer Customer { get; set; } 

     internal class Config : EntityTypeConfiguration<SalesOrder> 
     { 
      public Config() 
      { 

       HasRequired(r => r.Customer) 
        .WithMany(r => r.SalesOrder) 
        .HasForeignKey(r => r.CustomerId); 



      } 
     } 
    } 
} 

我Customer类：

using System.ComponentModel.DataAnnotations; 
using System.Collections.Generic; 
using System.ComponentModel.DataAnnotations.Schema; 
using System.Data.Entity.ModelConfiguration; 

namespace Accounting.Entity 
{ 
    [Table("Customer", Schema = "dbo")] 
    public class Customer 
    { 
     [Key] 
     [DatabaseGenerated(DatabaseGeneratedOption.Identity)] 
     public int? Id { get; set; } 

     public string FirstName { get; set; } 

     public string MiddleName { get; set; } 

     public string SecondName { get; set; } 

     public string PhoneNbr { get; set; } 

     public string Email { get; set; } 


     public virtual HashSet<SalesOrder> SalesOrder { get; set; } 

     internal class Config : EntityTypeConfiguration<Customer> 
     { 
      public Config() 
      { 

      } 
     } 
    } 
} 

Answer 1

两种方式：

1. 保存客户实体，和Entity Framework将回填的PK属性与它的ID。然后，您可以将此用于订单实体。

   db.Customers.Add(customer); 
   db.SaveChanges(); 
   order.CustomerId = customer.Id; // has a value now 
   

2. 只需通过导航属性将客户与订单关联即可。当您保存所有实体框架时，首先需要保存哪些关系，然后在相关实体中填写相应的FK ID。

   order.Customer = customer; 
   db.Orders.Add(order); 
   db.SaveChanges(); // customer is saved first and the id is set for order.CustomerId automatically