Gewusst wie: Sofortiges Abrufen vieler Objekte (LINQ to SQL)
Aktualisiert: November 2007
Sie können in einer Abfrage viele Objekte abrufen, indem Sie LoadWith verwenden.
Beispiel
Im folgenden Code wird die LoadWith-Methode verwendet, um ein Customer-Objekt und ein Order-Objekt abzurufen.
Dim db As New Northwnd("c:\northwnd.mdf")
Dim ds As DataLoadOptions = New DataLoadOptions()
ds.LoadWith(Of Customer)(Function(c) c.Orders)
ds.LoadWith(Of Order)(Function(o) o.OrderDetails)
db.LoadOptions = ds
Dim custQuery = From cust In db.Customers() _
Where cust.City = "London" _
Select cust
For Each custObj In custQuery
Console.WriteLine("Customer ID: " & custObj.CustomerID)
For Each ord In custObj.Orders
Console.WriteLine(vbTab & "Order ID: " & ord.OrderID)
For Each detail In ord.OrderDetails
Console.WriteLine(vbTab & vbTab & _
"Product ID: {0}", detail.ProductID)
Next
Next
Next
Northwnd db = new Northwnd(@"northwnd.mdf");
DataLoadOptions ds = new DataLoadOptions();
ds.LoadWith<Customer>(c => c.Orders);
ds.LoadWith<Order>(o => o.OrderDetails);
db.LoadOptions = ds;
var custQuery =
from cust in db.Customers
where cust.City == "London"
select cust;
foreach (Customer custObj in custQuery)
{
Console.WriteLine("Customer ID: {0}", custObj.CustomerID);
foreach (Order ord in custObj.Orders)
{
Console.WriteLine("\tOrder ID: {0}", ord.OrderID);
foreach (OrderDetail detail in ord.OrderDetails)
{
Console.WriteLine("\t\tProduct ID: {0}", detail.ProductID);
}
}
}