Question

我正在尝试使用Linq计算可空int的总和。我的查询如下：

int? surveysPromotersFromChatsGroup = (from surveyResult in surveyResultsFromChats
                                            where surveyResult.FirstScoreNPS.HasValue && surveyResult.GroupID == gr && surveyResult.FirstScoreNPS >= 9
                                            select surveyResult.FirstScoreNPS).Sum();

FirstScoreNPs字段是可以为空的int。我的问题是总和无论如何总是返回null。我看不出这背后的逻辑。我检查过，我确定某些实体确实在该字段中有值，而sum方法应该总结这些值。

我尝试的另一种方法是这样的：

int surveysPromotersFromChatsGroup = (from surveyResult in surveyResultsFromChats
                                      where surveyResult.FirstScoreNPS.HasValue && surveyResult.GroupID == gr && surveyResult.FirstScoreNPS >= 9
                                      select surveyResult.FirstScoreNPS).Sum(score => score.Value);

但我得到一个例外“linq无法将null值赋给类型为”的成员。

是否有办法使用linq从该字段中总结非空值？

surveyResultsFromChat实际上来自另一个查询：

                var surveyResultsFromChats = from surveyResult in db.SurveyResults
                                    join survey in db.Surveys on surveyResult.SurveyID equals survey.SurveyID
                                    join userGroup in db.UserGroupMaps on surveyResult.UserID equals userGroup.UserID
                                    where surveyResult.CreatedDate >= startDate && surveyResult.CreatedDate <= endDate && surveyResult.UserID.HasValue && surveyResult.ChatSessionID.HasValue
                                    select new { surveyResult.ResultID, survey.BrandID, userGroup.GroupID, surveyResult.CompletedDate, surveyResult.FirstScoreNPS };

我模型中的FirstScoreNPS是一个Nullable int。

Answer 1

你可以尝试

(from surveyResult in
 surveyResultsFromChats
where surveyResult.FirstScoreNPS.HasValue && surveyResult.GroupID == gr && 
surveyResult.FirstScoreNPS >= 9
   select surveyResult.FirstScoreNPS).
Select(score => score.Value ?? 0).Sum();

Linq与nullable int的总和

1 个答案: