Linq sum和null

Question

我有查询:

var qq = (from c in db.tblArcadeGames
        where
            c.IsDeleted == false &&
            c.ParentGameID == 0 &&
            c.Approved == true
        let aggPlays = c.Plays + db.tblArcadeGames.Where(v => v.ParentGameID == c.ID).Sum(v => (int?)v.Plays)
        orderby aggPlays descending
        select new { c, aggPlays })
        .Skip(Skip)
        .Take(Fetch);

foreach (var g in qq)
{
    HttpContext.Current.Response.Write("{" + g.aggPlays + "}\n");
}

当我aggPlays在上面的循环中打印出来时,它们会出现:

{21}
{}
{}
{}

问题似乎是如果没有记录则Sum()返回null.我不知道如何解决这个问题,以至于不c.Plays + null等于null而且只是c.Plays.

Answer 1

你可以通过不返回来纠正这个问题int?,而是int直接转换为:

.Sum(v => v.Plays ?? 0)