DataLoadOptions.AssociateWith Method

Definition

Namespace:

System.Data.Linq

Assembly:

System.Data.Linq.dll

Overloads

AssociateWith(LambdaExpression)	Filters the objects retrieved for a particular relationship.
AssociateWith<T>(Expression<Func<T,Object>>)	Filters objects retrieved for a particular relationship.

AssociateWith(LambdaExpression)

Filters the objects retrieved for a particular relationship.

public:
 void AssociateWith(System::Linq::Expressions::LambdaExpression ^ expression);

public void AssociateWith (System.Linq.Expressions.LambdaExpression expression);

member this.AssociateWith : System.Linq.Expressions.LambdaExpression -> unit

Public Sub AssociateWith (expression As LambdaExpression)

Parameters

expression

LambdaExpression

Identifies the query to be used on a particular one-to-many field or property. Note the following:

If the expression does not start with a field or property that represents a one-to-many relationship, an exception is thrown.

If an operator other than a valid operator appears in the expression, an exception is thrown. Valid operators are as follows:

Where

OrderBy

ThenBy

OrderByDescending

ThenByDescending

Take

Examples

Northwnd db = new Northwnd(@"c:\northwnd.mdf");
DataLoadOptions dlo = new DataLoadOptions();
dlo.AssociateWith<Customer>(c => c.Orders.Where(p => p.ShippedDate != DateTime.Today));
db.LoadOptions = dlo;
var custOrderQuery =
    from cust in db.Customers
    where cust.City == "London"
    select cust;

foreach (Customer custObj in custOrderQuery)
{
    Console.WriteLine(custObj.CustomerID);
    foreach (Order ord in custObj.Orders)
    {
        Console.WriteLine("\t {0}",ord.OrderDate);
    }
}

Dim db As New Northwnd("c:\northwnd.mdf")

Dim dlo As DataLoadOptions = New DataLoadOptions()
dlo.AssociateWith(Of Customer)(Function(c As Customer) _
        c.Orders.Where(Function(p) p.ShippedDate <> DateTime.Today))
db.LoadOptions = dlo

Dim custOrderQuery = _
    From cust In db.Customers _
    Where cust.City = "London" _
    Select cust

For Each custObj In custOrderQuery
    Console.WriteLine(custObj.CustomerID)
    For Each ord In custObj.Orders
        Console.WriteLine("{0}{1}", vbTab, ord.OrderDate)
    Next

Next

Remarks

In the following example, the inner loop iterates only over those Orders that have not been shipped today.

AssociateWith<T>(Expression<Func<T,Object>>)

Filters objects retrieved for a particular relationship.

public:
generic <typename T>
 void AssociateWith(System::Linq::Expressions::Expression<Func<T, System::Object ^> ^> ^ expression);

public void AssociateWith<T> (System.Linq.Expressions.Expression<Func<T,object>> expression);

member this.AssociateWith : System.Linq.Expressions.Expression<Func<'T, obj>> -> unit

Public Sub AssociateWith(Of T) (expression As Expression(Of Func(Of T, Object)))

Type Parameters

T

The type that is queried against.

If the type is unmapped, an exception is thrown.

Parameters

expression

Expression<Func<T,Object>>

Identifies the query to be used on a particular one-to-many field or property. Note the following:

If the expression does not start with a field or property that represents a one-to-many relationship, an exception is thrown.

If an operator other than a valid operator appears in the expression, an exception is thrown. Valid operators are as follows:

Where

OrderBy

ThenBy

OrderByDescending

ThenByDescending

Take

Examples

In the following example, the inner loop iterates only over those Orders that have not been shipped today.

Northwnd db = new Northwnd(@"c:\northwnd.mdf");
DataLoadOptions dlo = new DataLoadOptions();
dlo.AssociateWith<Customer>(c => c.Orders.Where(p => p.ShippedDate != DateTime.Today));
db.LoadOptions = dlo;
var custOrderQuery =
    from cust in db.Customers
    where cust.City == "London"
    select cust;

foreach (Customer custObj in custOrderQuery)
{
    Console.WriteLine(custObj.CustomerID);
    foreach (Order ord in custObj.Orders)
    {
        Console.WriteLine("\t {0}",ord.OrderDate);
    }
}

Dim db As New Northwnd("c:\northwnd.mdf")

Dim dlo As DataLoadOptions = New DataLoadOptions()
dlo.AssociateWith(Of Customer)(Function(c As Customer) _
        c.Orders.Where(Function(p) p.ShippedDate <> DateTime.Today))
db.LoadOptions = dlo

Dim custOrderQuery = _
    From cust In db.Customers _
    Where cust.City = "London" _
    Select cust

For Each custObj In custOrderQuery
    Console.WriteLine(custObj.CustomerID)
    For Each ord In custObj.Orders
        Console.WriteLine("{0}{1}", vbTab, ord.OrderDate)
    Next

Next

Remarks

For information about how to avoid cycles, see DataLoadOptions.