Creating a dynamic LINQ to Objects

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I have something like this where I need the selected filter variables to run at the runtime inside the LINQ statement, and I know the LING is not doing as I anticipate. Any answer would be appreciated.

C#

//code starts here.......
string strOnGameWhere = " && t.GameType.Contains(Texas)";

var tournament = from t in tournamentName
                             where t.BeachBar == "Bar" + strOnGameWhere
                             select t;

Posted 16-Aug-11 23:30pm

VelmuruganC

Updated 17-Aug-11 0:31am

Simon Bang Terkildsen

v3

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Simon_Whale 17-Aug-11 6:51am

In what way isn't it doing what you want? does it error? does it return incorrect results?

3 solutions

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Anurag Gandhi · Answer 1 · 2011-08-17T00:52:00

Solution 1

You can do this and many more by using expression trees in Linq. Click Here[^] for detail or Just google Google it[^].

Posted 17-Aug-11 0:52am

Anurag Gandhi

popojani · Answer 2 · 2011-08-17T12:19:00

Solution 2

I had the same problem earlier. Solution 1 is correct.
This forum post helped me a lot to achieve my goal:
http://social.msdn.microsoft.com/forums/en-US/linqprojectgeneral/thread/5edb3dd0-c778-47e2-b89d-a9c90a0bd1bc/

Posted 17-Aug-11 12:19pm

popojani

BillWoodruff · Answer 3 · 2011-08-17T18:30:00

One obvious thing that 'leaps out' at me looking at your code is that 'strOnGameWhere' is a string: when you add it to the string 'Bar,' of course you just get another string.

Clearly what you intend to do is to have the LINQ evaluation in progress evaluate the condition

&& t.GameType.Contains(Texas)

as part of the 'Where' clause, so what is executed is:

where t.BeachBar == "Bar" && t.GameType.Contains(Texas)

So, to me, the issue you are dealing with is how to call a variable function in a LINQ query that is executed inside a Where clause.

In LINQ terms, as I understand them, that means the LINQ expression must 'capture' an 'outer' variable reference, in this case ... a function ? ... a lambda ?

For understanding that, and so much else in .NET, I suggest you get and read Jon Skeet's masterpiece, "C# in Depth" (Manning Press, 2nd. edition).