使用实体框架的表中的相关数据

Posted 2023-04-13

【中文标题】使用实体框架的表中的相关数据

【英文标题】：Related data in tables using Entity Framework

【发布时间】：2020-07-20 15:10:02

【问题描述】：

我对有疑问。我有 2 个表“customer”&&“customerpreferences”，因为两个表都有客户，所以主键是“Id_Cus”。我回顾了急切的延迟加载。决定使用急切加载。我的服务在 WCF 上实现了 REST 架构。我想知道是否有必要在每个方法中编写 (Include (a => a.customerpreferences)) 。还有一个问题，在下面的截图中，我检查了我插入上述表达式的位置，但这不起作用，你能告诉我把这个表达式放在哪里吗？提前谢谢！

我的第三张图片代码

   using System;
   using System.Collections.Generic;
   using System.Linq;
   using System.Runtime.Serialization;
   using System.ServiceModel;
   using System.Text;
   using mysql.Data;
   using System.Data.Entity;

   using WcfRestFullService.Model;

   namespace WcfRestFullService
   
    // NOTE: You can use the "Rename" command on the "Refactor" menu to change 
    the class name "CustomerSevice" in code, svc and config file together.
    // NOTE: In order to launch WCF Test Client for testing this service, 
    please select CustomerSevice.svc or CustomerSevice.svc.cs at the Solution 
    Explorer and start debugging.
    public class CustomerSevice : ICustomerSevice
    
        MySQLEntities dc;
        public CustomerSevice()
        
            dc = new MySQLEntities();
        

        public List<customer> GetAllCustomer()
        
            var query = (from a in dc.customers
                         select a).Include(c=>c.customerpreference).Distinct();

            List<customer> CustomersList = new List<customer>();

            query.ToList().ForEach(x =>
            
                CustomersList.Add(new customer
                
                    Id_Cus = x.Id_Cus,
                    FirstName_Cus = x.FirstName_Cus,
                    LastName_Cus = x.LastName_Cus,
                    PhoneNum_Cus = x.PhoneNum_Cus,
                    Email_Cus = x.Email_Cus,
                );
            );
            return CustomersList;
        

        public customer CustomerDetails(string Id_Cus)
        
            customer Cust = new customer();
            try
            
                var query = (from a in dc.customers
                             where a.Id_Cus.Equals(Id_Cus)
                             select a).Distinct().FirstOrDefault();
                Cust.Id_Cus = query.Id_Cus;
                Cust.FirstName_Cus = query.FirstName_Cus;
                Cust.LastName_Cus = query.LastName_Cus;
                Cust.PhoneNum_Cus = query.PhoneNum_Cus;
                Cust.Email_Cus = query.Email_Cus;
            
            catch (Exception ex)
            
                throw new FaultException<string>(ex.Message);
            
            return Cust;
        

        // DELETE

        public void DeleteCustomer(string Id_Cus)
        
            //MySQLEntities Cust = new MySQLEntities(); //check the file 
        Model.edmx->ModelContext.tt->MySQLEntitys

            int k = Convert.ToInt32(Id_Cus);
            customer cur = (from n in dc.customers
                            where n.Id_Cus == k
                            select n).ToList().First();

            dc.Configuration.ValidateOnSaveEnabled = false;
            dc.customers.Remove(cur);
            dc.SaveChanges();
        

        //Insert/POST

        public void InsertCustomer(customer customerDataContract)
        
            //MySQLEntities Cust = new MySQLEntities();
            customer cust = new customer();

            cust.Id_Cus = Convert.ToInt32(customerDataContract.Id_Cus);
            cust.FirstName_Cus = customerDataContract.FirstName_Cus;
            cust.LastName_Cus = customerDataContract.LastName_Cus;
            cust.PhoneNum_Cus = 
        Convert.ToInt32(customerDataContract.PhoneNum_Cus);
            cust.Email_Cus = customerDataContract.Email_Cus;
            dc.customers.Add(cust);
            dc.SaveChanges();
        

        //Update/PUT
        public void UpdateCustomer(customer customerDataContract)
        
            //using (CustomerDataContract Cust = new CustomerDataContract())
            //using (MySQLEntities Cust = new MySQLEntities()) 
            
                int k = Convert.ToInt32(customerDataContract.Id_Cus);
                customer cust = dc.customers.Where(n => n.Id_Cus == 
           k).Include(a=>a.customerpreference).FirstOrDefault();

                cust.Id_Cus = Convert.ToInt32(customerDataContract.Id_Cus);
                cust.FirstName_Cus = customerDataContract.FirstName_Cus;
                cust.LastName_Cus = customerDataContract.LastName_Cus;
                cust.PhoneNum_Cus = 
              Convert.ToInt32(customerDataContract.PhoneNum_Cus);
                cust.Email_Cus = customerDataContract.Email_Cus;

                dc.SaveChanges();
            
        
    

```



[enter image description here][1]

[enter image description here][2]

[enter image description here][3]


  [1]: https://i.stack.imgur.com/zlATm.png
  [2]: https://i.stack.imgur.com/gQju8.png
  [3]: https://i.stack.imgur.com/6E7vw.png

【参考方案1】：

是的，您需要明确地预先加载客户偏好，如下所示：

(from a in dc.customers select a).Include(c => c.customerpreference).Distinct();

【讨论】：

是的，我做到了。数据未出现在第二个表中

您可以激活日志记录到控制台或调试以查看正在生成的查询，然后自己运行并尝试调试它

好的，谢谢你的提示。我以尝试运行它的方式编辑了我的代码。另一个问题，我需要在所有方法中规定表关系吗？或者只是在“GET”中注册