Tip 22 - How to make Include really Include

re: Tip 22 - How to make Include really Include

Vincent Ottens — Mon, 21 Mar 2011 11:38:35 GMT

Hi Alex,

Create post, it helped me a lot! I tried to use eagor loading wile doing a "group by into". This didn't work because of the anonymous that is created by the group by. your post directed me in the right direction.

Thnx

re: Tip 22 - How to make Include really Include

Anand — Fri, 22 Oct 2010 13:33:10 GMT

Hi Alex,

I am having a similar question as Rishi and Lori. I am coming to the conclusion that it is not possible to filter children records based during eager loading and include. Is that correct?

re: Tip 22 - How to make Include really Include

BJenkins — Wed, 30 Jun 2010 17:28:18 GMT

The line that reads:

var mem = (MemberExpression)param.Body;

should, instead, be:

var mem = (MemberExpression)exp.Body;

re: Tip 22 - How to make Include really Include

kevin sucre — Thu, 27 May 2010 16:14:02 GMT

dont wait for MS, just use expression trees:

public static class ObjectQueryExtension

{

public static ObjectQuery<T> Include<T,TProperty>(this ObjectQuery<T> obj, Expression<Func<T,TProperty>> exp)

where T:EntityObject

{

var mem = (MemberExpression)param.Body;

obj.Include(mem.Member.Name);

return obj;

}

re: Tip 22 - How to make Include really Include

neothemachine — Tue, 11 May 2010 12:22:02 GMT

This works with eager loading:

var r =

(from n in context.News.Include("Sources")

select n).ToList();

This doesn't work:

var r =

(from n in context.News.Include("Sources")

let calculation = true

select n).ToList();

The let-assignment could be anything later used in the query, maybe in a where-condition. But even the simple case with a "true" assignment drops eager loading.

This does work:

var r =

((from n in context.News

let calculation = true

select n) as ObjectQuery<Post>).Include("Sources").ToList();

Why??? This seems pretty stupid to me and is a major missing "feature".

re: Tip 22 - How to make Include really Include

Lori — Tue, 13 Apr 2010 23:12:56 GMT

Hi Alex,

I have the exact same issue as Rishi (Posted Feb 2). Being able to filter the children records on a parent would be AWESOME. I just started using EF and RIA services and I can't figure out how to do this one - and it's driving me crazy!

This was an excellent post!

re: Tip 22 - How to make Include really Include

Daniel Laberge — Fri, 26 Feb 2010 23:03:10 GMT

Thanks a lot for this post, this problem was driving me mad!

re: Tip 22 - How to make Include really Include

Rishi — Tue, 02 Feb 2010 14:03:45 GMT

Hi Alex

Is there anyway so that i can apply a filter on child records and only those child records which satisfy the filter condition should be included with Parent Entity.

To further Clarify.. My Problem is that i have ORDER Entity Type and ORDERDETAILS Entity Type. I want only those ORDERDETAILS included with ORDER Entity which satisfy some criteria not all the ORDERDETAILS.

re: Tip 22 - How to make Include really Include

Daniel Chambers — Fri, 22 Jan 2010 07:12:23 GMT

Just an FYI for anyone trying to do the "as ObjectQuery<Post>" in a compiled query: it won't work.

However, if you do a normal cast instead of using the "as" keyword, it will work. The syntax isn't as nice, but at least it works.

re: Tip 22 - How to make Include really Include

serge.mueller.zh.ch@gmail.com — Fri, 18 Dec 2009 09:05:58 GMT

Hello there,

i've got a related question.. is there a way to retrieve the includes that were made on a ObjectQuery<> so i may reapply them when needed (at the latest possible moment) ?

We use some basic functionality that predefines includes which get lost along the way..

that would be very helpful... otherwise we have a huge design breaking change ahead of us..

Yours serge