Dynamic "Not" by parameter in LINQ (Or any other code for that matter)

Question

Okay,

This may be really simple or it may not even be possible, or I am just having a brain freeze :)

Here is an example of what I am trying to do:

public void SomeMethod(bool include)
        {
            using (AccountDataContext db = AccountContextFactory.CreateContext())
            {
                if (include)
                {
                    var query = from a in db.FundingTypes where a.FundingTypeId == 1 select a;
                }
                else
                {
                    var query = from a in db.FundingTypes where a.FundingTypeId != 1 select a;
                }
            }
        }

I would like to dynamically change the != and = without having to write an entire new query. The query that I am using in real life is very large and I don't like code duplication.

Thought or Ideas?

Thanks

Answer 1

How about this:

public void SomeMethod(bool include, Func<int, bool> query)
{
    using (AccountDataContext db = AccountContextFactory.CreateContext())
    {
         var query = from a in db.FundingTypes where query(a.FundingTypeId) select a;
    }
}

Answer 2

Try this:

SomeMethod(bool include)
{
    using (AccountDataContext db = AccountContextFactory.CreateContext())
    {
        var query = from a in db.FundingTypes where !include ^ (a.FundingTypeId == 1) select a;
    }
}

Edit simplified the logic with an XOR

Answer 3

Try this:

var predicate = include
    ? (Func<FundingType, bool>) f => f.FundingTypeId == 1
    : (Func<FundingType, bool>) f => f.FundingTypeId != 1
return (from a in db.FundingTypes select a).Where(predicate);

Answer 4

That seems perfectly straightforward.

var predicate = include ? 
  (Func<int, bool>) x=>x == 1 : 
  (Func<int, bool>) x=>x != 1 ;
var query = from a in db.FundingTypes where predicate(a.FundingTypeId) select a;

Answer 5

Hi Jason,

How about this:

var query = 
    from a in db.FundingTypes 
    where (a.FundingTypeId == 1) == include 
    select a;

Joe