How to: Filter at the DataContext Level (LINQ to SQL)
You can filter EntitySets at the DataContext level. Such filters apply to all queries done with that DataContext instance.
Example
In the following example, DataLoadOptions.AssociateWith(LambdaExpression) is used to filter the pre-loaded orders for customers by ShippedDate.
Dim db As New Northwnd("c:\northwnd.mdf")
' Preload Orders for Customer.
' One directive per relationship to be preloaded.
Dim ds As DataLoadOptions = New DataLoadOptions()
ds.LoadWith(Of Customer)(Function(cust) cust.Orders)
ds.AssociateWith(Of Customer)( _
Function(cust) _
From ord In cust.Orders _
Where ord.ShippedDate <> DateTime.Today)
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: " & detail.ProductID)
Next
Next
Next
Northwnd db = new Northwnd(@"northwnd.mdf");
// Preload Orders for Customer.
// One directive per relationship to be preloaded.
DataLoadOptions ds = new DataLoadOptions();
ds.LoadWith<Customer>(c => c.Orders);
ds.AssociateWith<Customer>
(c => c.Orders.Where(p => p.ShippedDate != DateTime.Today));
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);
}
}
}