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Filter on entities futher away on the business object path
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bigfish View Drop Down
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Joined: 20-Mar-2009
Location: Australia
Posts: 36 		Post Options Post Options   Quote bigfish Quote  Post ReplyReply Direct Link To This Post Topic: Filter on entities futher away on the business object path
    Posted: 29-Oct-2009 at 12:00am
I cannot define an entity query that filters entities that are futher away than "nextdoor" to the root entity.
 
Please consider this:
 
var query = manager.Orders
.Include("Customer")
.Include("OrderDetails")
.Include("OrderDetails.Product")
.Where(a => a.OrderDetails.Product.ProductName == "Duff Beer");
The properties of the Product entity are not exposed to filter on. ProductName is not exposed via intellisense.
 
Do you know of another method to achieve this instead ?
 
My real world need has yet another entity on the object graph to navigate to as well.  At this stage I am considering the creation of a sql view (though not preferred).
 
Thanks kindly
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GregD View Drop Down
IdeaBlade
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Joined: 09-May-2007
Posts: 374 		Post Options Post Options   Quote GregD Quote  Post ReplyReply Direct Link To This Post Posted: 30-Oct-2009 at 6:52am
Bigfish:

LINQ wants the subject in the Where clause to be a single property of the object currently being examined (an Order, in your query). It doesn't know how to resolve the expression "a.OrderDetails.Product", because that isn't a single property of Order.

You need to rewrite your query as follows:

var query = manager.OrderDetails
  .Where(od => od.Product.ProductName == "Duff Beer")
  .Select(od => od.Order)
    .Include("Customer")
    .Include("OrderDetails")
    .Include("OrderDetails.Product");

First you obtain the set of OrderDetails that meet your condition; then from that set, project the related Orders. Note that the Includes are specified in relation to the projected type (Order), not the type initially referenced in the query (OrderDetail).
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bigfish View Drop Down
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Joined: 20-Mar-2009
Location: Australia
Posts: 36 		Post Options Post Options   Quote bigfish Quote  Post ReplyReply Direct Link To This Post Posted: 31-Oct-2009 at 1:03am
Thanks heaps Greg, much appreciated.  That helps a lot.
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GregD View Drop Down
IdeaBlade
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Joined: 09-May-2007
Posts: 374 		Post Options Post Options   Quote GregD Quote  Post ReplyReply Direct Link To This Post Posted: 03-Nov-2009 at 11:28am
Quite welcome, bigfish.
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