Question

有人可以帮我解决这个Linq查询并告诉我如何提取不同的产品名称

List<StatePlan> planTypes = (from ppt in context.PlanPlanTypes
     join pt in context.PlanTypes on ppt.PlanTypeRowID equals pt.PlanTypeRowID
     join ppts in context.PlanPlanTypeStates on ppt.PlanPlanTypeRowID equals ppts.PlanPlanTypeRowID
     join p in context.Plans on ppt.PlanRowID equals p.PlanRowID
     where ppts.StateCode == stateCode
     where p.IsActive == true
     select new StatePlan
     {   
         PlanID = p.PlanRowID,
         StateCode = stateCode,
         Name = p.Name,
         Description = p.Description,
         Disclaimer = p.Disclaimer,
         Sequence = p.DisplaySequence,
         //Rates = GetRates(p.PlanRowID),
         //Types = GetPlanTypes(p.PlanRowID, stateCode)
     }).ToList();
return planTypes;

Answer 1

我不确定我是否正确理解了这个问题，但如果您想要具有特定字段的项目，则可以先使用groupby +：

seq.GroupBy(item=>item.Name).Select(group=>group.First())

您也可以使用投影相等比较器，但我认为有点难看。对我来说使用Distinct意味着你不关心你得到哪些等价物品。而groupby +首先明确表明你想要第一个。

GroupBy还允许您在Select子句中收集其他信息，例如，有多少具有此名称的项目。

如果您只想要不带关联项的不同名称，请将select和distinct结合起来：

seq.Select(item=>item.Name).Distinct()

Answer 2

planTypes.Select(pt=>pt.Name).Distinct();

Answer 3

先将它分组，然后再进行第一次

List<StatePlan> planTypes = (from ppt in context.PlanPlanTypes
                                             join pt in context.PlanTypes on ppt.PlanTypeRowID equals pt.PlanTypeRowID
                                             join ppts in context.PlanPlanTypeStates on ppt.PlanPlanTypeRowID equals ppts.PlanPlanTypeRowID
                                             join p in context.Plans on ppt.PlanRowID equals p.PlanRowID
                                             where ppts.StateCode == stateCode
                                             where p.IsActive == true
                                             select new StatePlan
                                             {   
                                                 PlanID = p.PlanRowID,
                                                 StateCode = stateCode,
                                                 Name = p.Name,
                                                 Description = p.Description,
                                                 Disclaimer = p.Disclaimer,
                                                 Sequence = p.DisplaySequence,
                                                 //Rates = GetRates(p.PlanRowID),
                                                 //Types = GetPlanTypes(p.PlanRowID, stateCode)
                                             })
                                             .GroupBy(g => g.Name)
                                             .Select(s => s.First())
                                             .ToList();
            return planTypes;

Answer 4

您可以调用Distinct并为StatePlan

提供IEqualityComparer

Distinct

Answer 5

假设产品名称是Name列表中的planTypes属性，并且它是一个字符串：

List<string> productNames = planTypes.Select(t => t.Name).Distinct().ToList();

如何通过列表中的属性值删除重复项目＆lt;＆gt;

5 个答案: