Question

我在Entity Framework 7 RC1上使用LINQ左外连接。我们必须使用变通方法，因为左连接未正确实现，请参阅Left Outer Join with Entity Framework Core

var customers = from customer in _db.Customer
                join postcode in _db.Postcode
                    on customer.PostcodeID equals postcode.PostcodeID into custPCTmp
                from custPC in custPCTmp.DefaultIfEmpty()
                select new
                {
                    // Workaround for EF7 RC1.
                    Customer = customer,
                    CustPC = custPC
                };

// Workaround for EF7 RC1.
model.CustomersList = new List<CustomerListItemViewModel>();
foreach (var cust in customers)
{
    CustomerListItemViewModel custVM = new CustomerListItemViewModel()
    {
        CustomerID = cust.Customer.CustomerID,
        Name = cust.Customer.Name,
        Address = cust.Customer.Address,            
        Town = cust.CustPC == null ? string.Empty : cust.CustPC.Town,
        Postcode = cust.CustPC == null ? string.Empty : cust.CustPC.Postcode
    };
    model.CustomersList.Add(custVM);
}

我期待这样的结果（注意前3行应该有相同的城镇和邮政编码）：

Name    Address     Town    Postcode    
---------------------------------------
Name 1   Address 1   Town 1  Postcode 1

Name 2   Address 2   Town 1  Postcode 1

Name 3   Address 3   Town 1  Postcode 1

Name 4   Address 4   Town 4  Postcode 4

但是我得到了以下结果（重复第一条记录，三次）：

Name    Address     Town    Postcode    
--------------------------------------
Name 1  Address 1   Town 1  Postcode 1

Name 1  Address 1   Town 1  Postcode 1

Name 1  Address 1   Town 1  Postcode 1

Name 4  Address 4   Town 4  Postcode 4

我可以看到它是由于客户与PostcodeID上的邮政编码的连接，但为什么它会像这样重复？数据库中的数据看起来很好。

亲切的问候，

Rasika

实体框架7 RC1左外连接重复行

0 个答案: