Question

我有一个linq如下：

var finalist = (from b in GeneralAction.EM().Vwmembersummarydetails
                where selectedPersonId.Contains(b.Id)
                select new GeneralCommonFunctions.MemberDetailSumary
                {
                  Index = 0,
                  ProjectText = string.Join(", ", (from d in GeneralAction.EM().Member_has_properties
                                                   join e in GeneralAction.EM().Properties on d.Property_id equals e.Id
                                                   where d.IsDeleted == 0 && d.Member_id == b.Id && e.ProjectType_id == Convert.ToInt32(projectTypeId)
                                                   select e.Project.Description).Distinct().ToArray()),
                  PropertyText = string.Join(", ", (from f in GeneralAction.EM().Member_has_properties
                                                    join g in GeneralAction.EM().Properties on f.Property_id equals g.Id
                                                    where f.IsDeleted == 0 && f.Member_id == b.Id && g.ProjectType_id == Convert.ToInt32(projectTypeId)
                                                    select g.LotNum).ToArray()),
                  PurchasePrice = GeneralCommonFunctions.GetTotalPurchasePriceByProjectType(b.Id, projectTypeId),
                  Name = b.Name,
                  Email = b.Email,
                  }).AsQueryable();

我想问一下，如何忽略这两个条件：

e.ProjectType_id == Convert.ToInt32（projectTypeId）

g.ProjectType_id == Convert.ToInt32（projectTypeId）

当projectTypeId为null或0时。

Answer 1

要忽略这些条件，只需使用logical或：

(projectTypeId == null || Convert.ToInt32(projectTypeId) == 0 || e.ProjectType_id == Convert.ToInt32(projectTypeId))

要调用不同的函数，请使用第三个运算符。请注意，这可能不适用于Linq to SQL -

(projectTypeId == null ? GeneralCommonFunctions.GetTotalPurchasePrice(b.Id) : GeneralCommonFunctions.GetTotalPurchasePriceByProjectType(b.Id, projectTypeId))

Answer 2

我是投票的人。 SO的原因是寻找真正难以找到的解决方案。但在发布之前，你似乎没有尝试过。

解决方案是用你自己的话说的 -

e.ProjectType_id == Convert.ToInt32（projectTypeId）

g.ProjectType_id == Convert.ToInt32（projectTypeId）

当projectTypeId为null或0时。

因此，将该英语句子转换为代码。

&& e.ProjectType_id == Convert.ToInt32(projectTypeId)

将成为 -

&& ((e.ProjectType_id != null && e.ProjectType_id != "0") ? e.ProjectType_id == Convert.ToInt32(projectTypeId) : true)

然后，您可以更好地优化它，如@netmage所述 -

(projectTypeId == null || Convert.ToInt32(projectTypeId) == 0 || e.ProjectType_id == Convert.ToInt32(projectTypeId))

同样地，

当projectTypeId为null时，如何调用GeneralCommonFunctions.GetTotalPurchasePrice（），当projectTypeId不为null时，调用GeneralCommonFunctions.GetTotalPurchasePriceByProjectType（）。

同样变为 -

PurchasePrice = projectTypeId = null ? GeneralCommonFunctions.GetTotalPurchasePrice(...) : GeneralCommonFunctions.GetTotalPurchasePriceByProjectType(b.Id, projectTypeId),

如何忽略LinQ中的特殊情况

2 个答案: