How to write dynamic where in LINQ?

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.NET3.0

I have a LinQ query as below

SQL

var filtered=from c in country
         where c.Id>=5
         select c;

Now i need to have the operator '>=' to be dynamic i.e., the operator may be '>=' or '==' or '<=' etc depending on a certain criteria and the query should execute based on that operator. How to achieve this in LinQ?

Posted 18-Jul-11 20:48pm

abi1988

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2 solutions

Solution 2

How to use the close button in crystal report

Posted 19-Jul-11 0:06am

AmuthaRamasamy

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Christoph Keller · Accepted Answer · 2011-07-18T21:07:00

Solution 1

Hi,

You could add a check-function which returns a bool.
Something like this:

C#

private bool TestValue(int id, int contiditon)
{
    if (condition == 1)
    {
        return id <= 5;
    }
    else
    {
        return id >= 5;
    }
}

/* your linq query would look like this */
var filtered = from c in country
               where TestValue(c.Id, c.Condition)
               select c;

This is completely untested so it could contain errors ;)
Hope this helps.

Best regards and happy coding,
Stops

Posted 18-Jul-11 21:07pm

Christoph Keller

Comments

abi1988 19-Jul-11 3:20am

@sTOPs:Thanks for the reply. I know to use an if..else or select..case for this scenario. I need to minimize the code by doing something else from the above mentioned techniques.So, is there any other possibilities?

Christoph Keller 19-Jul-11 3:25am

You could write it this way:

var filtered = from c in country
where (c.Condition == 1 && c.Id >= 5) ||
(c.Condition != 1 && c.Id <= 5)
select c;

so first check for the condition and combine it (by using '&&') with the second check.

As far as I know, there is no possibility to have a "dynamic" check, whathever this means. The check must be defined somewhere so it is always static.

Hope this helps.

abi1988 19-Jul-11 3:42am

Yes..this technique may be a better way for this scenario. this reduces the complexity of the code.
Thanks a lot sTOPs.:)

Christoph Keller 19-Jul-11 8:32am

you're welcome! :)