Limiting query size with entity framework

Question

this is a simple question (I think), but I have not been able to find a solution. I know with other types of queries, you can add a limit clause that makes the query only return up to that many results. Is this possible with an entity query?

var productQuery = from b in solutionContext.Version
                               where b.Product.ID != 1 && b.VersionNumber == b.Product.ActiveNumber
                               orderby b.Product.LastNumber
                               select b;

I just want to make it so this query only returns 25 version objects. Thanks for any help.

score 54 · Accepted Answer · answered Jul 27 '10 at 14:12

54

sure.. for example you can do it like this:

var productQuery = from b in solutionContext.Version
                           where b.Product.ID != 1 && b.VersionNumber == b.Product.ActiveNumber
                           orderby b.Product.LastNumber
                           select b;

var limitedProductQuery = productQuery.Take(25);

also you may need this for paging results:

var pagedProductQuery = productQuery.Skip(25 * page).Take(25)

answered Jul 27 '10 at 14:12

Łukasz W.

9,538
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That's going to select everything from the table before restricting the results in memory. – David Neale Jul 27 '10 at 14:16
10

David.. no, its not.. Its querable object.. its equivalent to query... It will execute when he will try to get some objects or use ToList method etc. – Łukasz W. Jul 27 '10 at 14:16
@David, what in that original query forces execution? – Marc Jul 27 '10 at 14:17
@LukaszW.pl, sorry I didn't realise that. – David Neale Jul 27 '10 at 14:29

score 5 · Answer 2 · answered Jul 27 '10 at 14:12

What you're looking for is Take:

var productQuery = (from b in solutionContext.Version
                   where b.Product.ID != 1 
                       && b.VersionNumber == b.Product.ActiveNumber
                   orderby b.Product.LastNumber
                   select b).Take(25);

score 4 · Answer 3 · answered Jul 27 '10 at 14:13

4

var productQuery = (from b in solutionContext.Version
                           where b.Product.ID != 1 && b.VersionNumber == b.Product.ActiveNumber
                           orderby b.Product.LastNumber
                           select b).Take(25);

answered Jul 27 '10 at 14:13

David Neale

16,498
6
59
85

Limiting query size with entity framework

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