Question

I m trying to track down a crash in some existing code in a web app I inherited.. I ve traced this down to a single LINQ expression:

var projInfo = (from v in context.TPM_PROJECTVERSION
                join p in context.TPM_PROJECT on v.PROJECTID equals p.PROJECTID
                join pto in context.TPM_USER on v.TPM_USER1.USERID equals pto.USERID
                join pt in context.TPM_PROJECTTYPES on p.PROJECTTYPEID equals pt.PROJECTTYPEID
                where v.PROJECTID == projectId && v.VERSIONID == versionId
                select new
                {
                    ProjectName = v.NAME,
                    ProjectType = pt.SHORTNAME,
                    ProjectDesc = v.DESCRIPTION,
                    BusinessLaunchData = p.BUSINESSLAUNCHDATE,
                    BusinessSponsor = (v.TPM_USER3.FIRSTNAME + " " + v.TPM_USER3.LASTNAME),
                    PrimaryTrainingOwner = (pto.FIRSTNAME + " " + pto.LASTNAME)
                }).First();

错误是“数量不包括任何内容”,我已追查到这一行:

join pto in context.TPM_USER on v.TPM_USER1.USERID equals pto.USERID

如果美国电力局1 无效,则该行不会归还。相反,我只需要掌握初级知识,而只是作废或空白。基本上,我需要做的是教育、青年和体育部,并在确定初级人才时对此进行检查。是否有办法更新该准则的表述,以处理这一问题? 感谢!

Answer 1

我认为我找到了解决办法。我不胜感激,对这是否是最佳办法或合成物或以何种方式? 感谢!

var projInfo = (from v in context.TPM_PROJECTVERSION
                join p in context.TPM_PROJECT on v.PROJECTID equals p.PROJECTID
                join pto in context.TPM_USER on v.TPM_USER1.USERID equals pto.USERID into primaryowner
                from subpto in primaryowner.DefaultIfEmpty()
                join pt in context.TPM_PROJECTTYPES on p.PROJECTTYPEID equals pt.PROJECTTYPEID
                where v.PROJECTID == projectId && v.VERSIONID == versionId
                select new
                {
                    ProjectName = v.NAME,
                    ProjectType = pt.SHORTNAME,
                    ProjectDesc = v.DESCRIPTION,
                    BusinessLaunchData = p.BUSINESSLAUNCHDATE,
                    BusinessSponsor = (v.TPM_USER3.FIRSTNAME + " " + v.TPM_USER3.LASTNAME),
                    PrimaryTrainingOwner = subpto == null ? String.Empty : (subpto.FIRSTNAME + " " + subpto.LASTNAME)
                }).First();

友情链接