Question

我有一个Entity Framework模型，其中有一个“Customers”和一个“CustomerPhones”表。客户可以拥有多个电话号码，因此“客户”实体具有“电话”集合。我可以毫无问题地查询模型：

using (CustomerEntities context = new CustomerEntities())
{
    Customer customer = context.Customers.FirstOrDefault();
    CustomerPhone phone = customer.Phones.FirstOrDefault();

    MessageBox.Show(customer.Name + " " + phone.Number);
}

这个模型对于我需要做的事情太复杂了（尽管我的例子是基本的）所以我试图把它归结为更简单的POCO。以下是两个简单的类：

public class SimplePhone
{
    public int Id { get; set; }
    public string Number { get; set; }
}

public class SimpleCustomer 
{
    public int Id { get; set; }
    public string Name { get; set; }

    //Phones is a list because a single Customer can have multiple phone numbers
    public List<SimplePhone> Phones { get; set; }
}

我可以使用“IQueryable”的“Select”方法填充对象的简单属性：

using (CustomerEntities context = new CustomerEntities())
{
   IQueryable<SimpleCustomer> customers = context.Customers.Select(
           c => new SimpleCustomer
           {
               Id = c.Id,
               Name = c.Name
           }
       );

   SimpleCustomer customer = customers.FirstOrDefault();

   MessageBox.Show(customer.Name);
}

所以我的问题很简单：如何填充列表中的“电话”属性？

using (CustomerEntities context = new CustomerEntities())
{
   IQueryable<SimpleCustomer> customers = context.Customers.Select(
           c => new SimpleCustomer
           {
               Id = c.Id,
               Name = c.Name
               Phones = ///????
           }
       );

   SimpleCustomer customer = customers.FirstOrDefault();
   SimplePhone phone = customer.Phones.FirstOrDefault();

   MessageBox.Show(customer.Name + " " + phone.Number);
}

如果我不清楚和/或您需要更多细节，请告诉我。

谢谢！

Answer 1

我不确定您的问题是否还有其他问题，但据我了解，您只需致电ToList，它就会被列为一个列表：

IQueryable<SimpleCustomer> customers = 
    context.Customers.Select(c => new SimpleCustomer
    {
        Id = c.Id,
        Name = c.Name,
        Phones = c.Phones.Select(p => new SimplePhone 
                 {
                     Id = p.Id, // Unless you want the custom Id, i.e. c.Id
                     Number = p.Number
                 }).ToList();
    });

IQueryable.Select到List类型子POCO

1 个答案: