?
Solved

LINQ and NOT IN / Contains Subquery Problem

Posted on 2010-08-26
4
Medium Priority
?
1,210 Views
Last Modified: 2013-11-11
I am trying to return a set of data using LINQ and Entity Framework which will only return items where a related item exists and fulfils a set of criteria.

I have the following code:

 
'Gets a list of customer IDs which have callbacks set
                Dim Callbacks = (From f In MyContext.Callbacks.Include("Customer") Where (f.TypeId > 0) Select f.Customer.Id).ToList

                'Select customers who DO NOT have callbacks set
                Customers = From c In MyContext.Customers _
                    Where (c.StatusId = 2) _
                    And Not Callbacks.Contains(c.Id) _
                    Select c

Open in new window


However, I am getting an error:

LINQ to Entities does not recognize the method 'Boolean Contains(Int32)' method, and this method cannot be translated into a store expression.

How can I do this with LINQ? I have tried using one LINQ query (with a nested subquery instead of the Callbacks.Contains(c.Id) ) and two LINQ queries as shown above
0
Comment
Question by:pipelineconsulting
  • 2
  • 2
4 Comments
 
LVL 10

Expert Comment

by:joriszwaenepoel
ID: 33529397
You could sole it like this:

Customers = From c In MyContext.Customers _
                    Where (c.StatusId = 2) _
                    Select c

For each cb in Callbacks
    Customers = From c in Customers Where c.ID <> cb.ID
Next

Then, when the query is executed, the SQL will contain a list of OR operators instead of a single IN operator, but it is the only way I have been able to work around this error.
0
 

Author Comment

by:pipelineconsulting
ID: 33529666
That doesn't quite make sense

For each cb in Callbacks
    Customers = From c in Customers Where c.ID <> cb.ID
Next


Compairing c.ID to cb.ID is not correct as they are two different entities. Each customer has several callbacks but I don't think that comparing their primary keys will give me what I need.

I need only the customers that do not have a callback in place.
0
 
LVL 10

Accepted Solution

by:
joriszwaenepoel earned 1000 total points
ID: 33529691
Sorry,

Since cb is already a customerID, I meant:

For each cb in Callbacks
    Customers = From c in Customers Where c.ID <> cb
Next
0
 

Author Closing Comment

by:pipelineconsulting
ID: 33529842
Seems to do the trick! There is probably a more elegant solution but for now it is fine.
0

Featured Post

The new generation of project management tools

With monday.com’s project management tool, you can see what everyone on your team is working in a single glance. Its intuitive dashboards are customizable, so you can create systems that work for you.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Just a quick little trick I learned recently.  Now that I'm using jQuery with abandon in my asp.net applications, I have grown tired of the following syntax:      (CODE) I suppose it just offends my sense of decency to put inline VBScript on a…
International Data Corporation (IDC) prognosticates that before the current the year gets over disbursing on IT framework products to be sent in cloud environs will be $37.1B.
Enter Foreign and Special Characters Enter characters you can't find on a keyboard using its ASCII code ... and learn how to make a handy reference for yourself using Excel ~ Use these codes in any Windows application! ... whether it is a Micr…
How to fix display issue, screen flickering issue when I plug in power cord to the machine. Before I start explaining the solution lets check out once the issue how it looks like after I connect the power cord. most of you also have faced this…
Suggested Courses

601 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question