CODEWITHSUNDEEP
c#.netlinq
narudnarud
narudnarud

Reputation: 3

Linq query run over list of parameters

I have a requirement to create a linq query that selects data from a database table where a certain functional result is true.

I am using linq-to-sql and the function works well and I can write a basic query to get the data.

My issue is that I have an in-memory list of parameters and I essentially need to run the linq query multiple times (once for every parameter list item) and aggregate the results.

I have tried using the .Any() as a join but linq doesn't like joining non-database result sets with database result sets.

Some Sample Code:

Parameter list: // lets call it "l"
{    
 One,
 Two,
 Three
}

Query

From w in words where funcWord(l.item) == true select w;

So I would require a query that can run the above query once for every item in l and aggregate the results.

Any help is appreciated.

Thanks.

Upvotes: 0

Views: 1111

Answers (2)

Risky Martin
Risky Martin

Reputation: 2531

Multiple from statements will go through every combination, sort of like nested foreach statements:

from item in list
from w in words
where funcWord(item, w.name) == true
select w;

Interestingly, this gets translated to a SelectMany statement that is similar to Arithmomaniac's answer.

Upvotes: 1

Arithmomaniac
Arithmomaniac

Reputation: 4804

Try SelectMany, which aggregates the result of a one-to-many function, applied to each member.

In this case, the members are the elements of list, and the one-to-many function is your above, l-dependent query (though I rewrote it as a lambda function.)

list.SelectMany(l => words.Where(w => funcWord(l.item, w.name)));

Upvotes: 0

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