Linq: Sum int

Question

Linq: Sum int

I get " A null value cannot be assigned to a member of type System.Int32, which is a non-nullable value type " when I execute Sum () of my empty statement. ResultView works fine, but

var r = from v in DataContext.Visits
        join bs in DataContext.BaseContents on v.BaseContentID equals bs.Id
        where (bs.CreatedBy == userId) && (v.DateVisited.Year == workDate.Year) &&
        (v.DateVisited.Month == workDate.Month) && (v.DateVisited.Day == workDate.Day) &&
        (v.IsPreviewed == false) && (bs.ProfileProjectId != null)
        select v;

int? number = r.Sum( v => v.Counter);

or

var r = from v in DataContext.Visits
        join bs in DataContext.BaseContents on v.BaseContentID equals bs.Id
        where (bs.CreatedBy == userId) && (v.DateVisited.Year == workDate.Year) &&
        (v.DateVisited.Month == workDate.Month) && (v.DateVisited.Day == workDate.Day) &&
        (v.IsPreviewed == false) && (bs.ProfileProjectId != null)
        select v.Counter;

int? number = r.Sum(v);

doesn't work with the same exception.

+2

linq excel sum linq-to-sql

st78 12 oct. 09 at 14:33

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3 answers

bruno conde · Answer 1 · 2009-10-12T14:37:36+0000

Try this (updated):

int number = r.Sum(v => (int?)v.Counter) ?? 0;

Matthew whited · Answer 2 · 2009-10-12T15:15:04+0000

Could you include some sample data? At least you can grab r.ToList () and look at the values manually. From what I can see it looks like it should work fine. Also make sure v.BaseContentID, bs.Id and v.DateVisited are not NULL. (especially id columns). Any referenced null integers can throw this exception. Not only those listed in the Select clause

var r = from v in DataContext.Visits
        join bs in DataContext.BaseContents on v.BaseContentID equals bs.Id
        where (bs.CreatedBy == userId) 
            && (v.DateVisited.Date == workDate.Date)
            && (!v.IsPreviewed) 
            && (bs.ProfileProjectId.HasValue)
        select v;

int? number = r.Sum(v => v.Counter);

LJM · Answer 3 · 2009-10-12T14:38:42+0000

It seems like put && (v.Counter != null)

will filter out all nulls for that value before running the sum.

Linq: Sum int

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