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How to access nested navigation properties

Printed From: IdeaBlade
Category: DevForce
Forum Name: DevForce 2009
Forum Discription: For .NET 3.5
URL: http://www.ideablade.com/forum/forum_posts.asp?TID=1619
Printed Date: 05-Apr-2025 at 9:27pm


Topic: How to access nested navigation properties
Posted By: anwar
Subject: How to access nested navigation properties
Date Posted: 18-Jan-2010 at 11:43am
Hello All,
 
My entity model contains multilevel navigation properties, can any one help  me how to access multilevel/nested  navigation properties.
 
The sample in developer guide shows one level of navigation access. here is the code snippet from dev. guide.
 

// Retrieve a collection of related entities using a collection navigation property

targetOrder.OrderDetails.PendingEntityListResolved +=

new EventHandler<PendingEntityListResolvedEventArgs<OrderDetail>>(

OrderDetails_PendingEntityListResolved);

 

void OrderDetails_PendingEntityListResolved(object sender,

PendingEntityListResolvedEventArgs<OrderDetail> e) {

Console.WriteLine("OrderDetails retrieved: {0}", e.ResolvedEntities.Count);

}

 
Help will be appricitated.
 
Thanks,
Anwar


Replies:
Posted By: davidklitzke
Date Posted: 19-Jan-2010 at 3:52pm
Nested navigation properties should end with either a scalar (e.g., Order.Customer.FirstName) or with a list or collection (e.g., Order.Customer.Orders).  If you are using a scalar, use a scalar navigation property (such as one that requires PendingEntity). If you are querying for a collection, use a collection navigation property (such as one that requires PendingEntityList).

Posted By: GregD
Date Posted: 20-Jan-2010 at 3:56pm
Anwar:

I'm going to expand a bit on David's answer with a couple of examples of accessing multilevel navigation properties, using entities from NorthwindIB:

     anOrder.Customer.Orders

would retrieve all of the Orders (i.e., a collection) for the Customer associated with anOrder.

     anOrderDetail.Product.Supplier

would return the Supplier (i.e., a scalar) associated with the Product mentioned in anOrderDetail.

When operating in an asynchronous environment like Silverlight, you will often want to be notified when retrieval of the referenced entity or entities has completed.  For a collection navigation property like anOrder.Customer.Orders you would handle the PendingEntityListResolved event on the referenced property. For a scalar navigation property like anOrderlDetail.Product.Supplier you would handle the PendingEntityResolved event on the referenced property.


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