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ObjectQuery<T>.Include(String) Method

  • Reference

Definition

Namespace:
System.Data.Objects
Assembly:
System.Data.Entity.dll

Specifies the related objects to include in the query results.

public:
 System::Data::Objects::ObjectQuery<T> ^ Include(System::String ^ path);
public System.Data.Objects.ObjectQuery<T> Include (string path);
member this.Include : string -> System.Data.Objects.ObjectQuery<'T>
Public Function Include (path As String) As ObjectQuery(Of T)

Parameters

path
String

Dot-separated list of related objects to return in the query results.

Returns

ObjectQuery<T>

A new ObjectQuery<T> with the defined query path.

Exceptions

ArgumentNullException

path is null.

ArgumentException

path is empty.

Examples

using (AdventureWorksEntities context =
    new AdventureWorksEntities())
{
    // Define an object query with a path that returns
    // orders and items for a specific contact.
    Contact contact =
        context.Contacts.Include("SalesOrderHeaders.SalesOrderDetails")
        .FirstOrDefault();

    // Execute the query and display information for each item
    // in the orders that belong to the first contact.
    foreach (SalesOrderHeader order in contact
        .SalesOrderHeaders)
    {
        Console.WriteLine(String.Format("PO Number: {0}",
            order.PurchaseOrderNumber));
        Console.WriteLine(String.Format("Order Date: {0}",
            order.OrderDate.ToString()));
        Console.WriteLine("Order items:");
        foreach (SalesOrderDetail item in order.SalesOrderDetails)
        {
            Console.WriteLine(String.Format("Product: {0} "
                + "Quantity: {1}", item.ProductID.ToString(),
                item.OrderQty.ToString()));
        }
    }
}

Remarks

Query paths can be used with Entity SQL and LINQ queries.

Paths are all-inclusive. For example, if an include call indicates Include("Orders.OrderLines"), not only will OrderLines be included, but also Orders. For more information, see Loading Related Objects.

When you call the Include method, the query path is only valid on the returned instance of the ObjectQuery<T>. Other instances of ObjectQuery<T> and the object context itself are not affected.

Because the Include method returns the query object, you can call this method multiple times on an ObjectQuery<T> to specify multiple paths for the query, as in the following example:

// Create a SalesOrderHeader query with two query paths,
// one that returns order items and a second that returns the
// billing and shipping addresses for each order.
ObjectQuery<SalesOrderHeader> query =
    context.SalesOrderHeaders.Include("SalesOrderDetails").Include("Address");

Applies to

See also