我正在尝试使用 Linq 计算可为 null int 的总和。我的查询如下所示:
int? surveysPromotersFromChatsGroup = (from surveyResult in surveyResultsFromChats
where surveyResult.FirstScoreNPS.HasValue && surveyResult.GroupID == gr && surveyResult.FirstScoreNPS >= 9
select surveyResult.FirstScoreNPS).Sum();
FirstScoreNPs 字段是一个可为 null 的 int。我的问题是无论如何总和总是返回 null。我看不出这背后的逻辑。我检查过,并且确定某些实体在该字段中具有值,并且 sum 方法应该对这些值进行求和。
我尝试过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);
但是我得到一个异常“linq 空值不能分配给具有类型的成员”。
有没有办法使用 linq 对该字段中的非空值求和?
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 };
我的模型中的 FirstScoreNPS 是一个 Nullable int。
最佳答案
你可以试试
(from surveyResult in
surveyResultsFromChats
where surveyResult.FirstScoreNPS.HasValue && surveyResult.GroupID == gr &&
surveyResult.FirstScoreNPS >= 9
select surveyResult.FirstScoreNPS).
Select(score => score.Value ?? 0).Sum();
关于c# - Linq 与可空 int 的 sum,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/12623555/