DevForce Community Forum : Using Entity Linq with Custom Properties

Using Entity Linq with Custom Properties : Hi mseeli; I just discovered...

Fri, 28 Jan 2011 12:19:43 -700

Author: DenisK
Subject: 2457
Posted: 28-Jan-2011 at 12:19pm

Hi mseeli;

I just discovered that thefollowing can be done to create a dynamic OfType query, not quite a Linq onethough. Hope it can be useful to you in some ways.

Employee - Master type

CurrentEmployee - Sub type ofEmployee

var typeToBeSelected =typeof(CurrentEmployee);

var qBaseWeak =(IQueryable)TypeFns.ConstructGenericInstance(typeof(EntityQuery<>),entityType);

var rBaseWeak =mgr.ExecuteQuery((IEntityQuery)qBaseWeak);

typeToBeSelected could bea sub type and when I tested it, it was able to retrieve the sub type withouthaving to retrieve all the master type first into the client.

Using Entity Linq with Custom Properties : Hi mseeli;You would actually need...

Fri, 21 Jan 2011 17:15:56 -700

Author: DenisK
Subject: 2457
Posted: 21-Jan-2011 at 5:15pm

Hi mseeli;

You would actually need to use OfType<> with your query. Constructing a dynamic OfType Linq query is currently not possible.

To create a similar function that runs on the server, you would need to create a server method and call that server method using EntityManager.InvokeServerMethod or EntityManager.InvokeServerMethodAsync. You can pass in the typeToBeSelected argument to that server method and run the same logic as

var ordersOfCertainType = orders.Where(x=>x.Type.IsOfType( typeToBeSelected));

Please see http://drc.ideablade.com/xwiki/bin/view/Documentation/QueryRSMC for some code samples.

Hope this helps.

Using Entity Linq with Custom Properties : I have a large number of orders.Each...

Fri, 21 Jan 2011 06:07:34 -700

Author: mseeli
Subject: 2457
Posted: 21-Jan-2011 at 6:07am

I have a large number of orders.

Each order is of a type.

The types are in a hierarchical tree: there is one master-type and then many branches and layers down of subtypes and sub-types of those and so on.

I want to be able to query the orders by selecting one type and getting back all the orders of this type plus all the orders that are of a subtype of this type (all the way down).

I created a property on the type called IsOfType(Type) in which I check if a type belongs to the branch of certain type.

It works fine. But I have to first get all the orders down to my client before I can use this property in a linq where statement

var ordersOfCertainType = orders.Where(x=>x.Type.IsOfType( typeToBeSelected));

What I would like to do is to use my property in a Entity query i.e.:

manager.GetQuery.Where(.......) this does not work. Is there a way to get it to work with custom properties?

and if not how would I go about creating a function that runs on the server that does the selection before it sends the resulting orders over the wire.

thank you.