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DataServiceContext.AddLink Method

Adds the specified link to the set of objects the DataServiceContext is tracking.

Namespace:  System.Data.Services.Client
Assembly:  System.Data.Services.Client (in System.Data.Services.Client.dll)

public void AddLink(
	Object source,
	string sourceProperty,
	Object target


Type: System.Object

The source object for the new link.

Type: System.String

The name of the navigation property on the source object that returns the related object.

Type: System.Object

The object related to the source object by the new link.


When source, sourceProperty, or target are null.


If a link already exists.


If either the source or target objects are in a Detached or Deleted state.


If sourceProperty is not a collection.

Notifies the DataServiceContext that a new link exists between the related source and target objects and that the link is represented by the specified source property. The DataServiceContext adds this link to the set of newly created links that will be sent to the data service on the next call to SaveChanges.

Links are one-way relationships. Because associations are bi-directional, in a one-to-one association you must call either AddLink again to create the reverse link, and in a many-to-one association you must call SetLink to create a reference link to the "one" end of the association.

The target object must be of the type identified by the sourceProperty parameter or a subtype of the type.

The following example shows how to use the AddLink and SetLink methods to create links that define relationships. In this example, the navigation properties on the Order_Details object are also explicitly set. This example uses the DataServiceContext generated by the Add Service Reference tool based on the Northwind data service, which is created when you complete the ADO.NET Data Services quickstart.

int productId = 25;
string customerId = "ALFKI";

Order_Details newItem = null;

// Create the DataServiceContext using the service URI.
NorthwindEntities context = new NorthwindEntities(svcUri);

    // Get the specific product.
    var selectedProduct = (from product in context.Products
                           where product.ProductID == productId
                           select product).Single();

    // Get the specific customer.
    var cust = (from customer in context.Customers.Expand("Orders")
                where customer.CustomerID == customerId
                select customer).Single();

    // Get the first order. 
    Orders order = cust.Orders.FirstOrDefault();

    // Create the a new order detail for the specific product.
    newItem = Order_Details.CreateOrder_Details(
        order.OrderID, selectedProduct.ProductID, 10, 5, 0);

    // Add the new order detail to the context.

    // Add links for the one-to-many relationships.
    context.AddLink(order, "Order_Details", newItem);
    context.AddLink(selectedProduct, "Order_Details", newItem);

    // Set reference links for the many-to-one relationships.
    context.SetLink(newItem, "Orders", order);
    context.SetLink(newItem, "Products", selectedProduct);

    // Add the new order detail to the collection, and 
    // set the reference to the product.
    newItem.Products = selectedProduct;

    // Send the inserts to the data service.
catch (DataServiceQueryException ex)
    throw new ApplicationException(
        "An error occurred when saving changes.", ex);

// Handle any errors that may occur during insert, such as  
// a constraint violation. 
catch (DataServiceRequestException ex)
    throw new ApplicationException(
        "An error occurred when saving changes.", ex);

Windows 7, Windows Vista, Windows XP SP2, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003

The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

.NET Framework

Supported in: 3.5 SP1