LINQ 删除分组中具有特定值的项目答案

【问题标题】：LINQ remove items with specific value in group byLINQ 删除分组中具有特定值的项目
【发布时间】：2015-05-28 09:49:45
【问题描述】：

我有代码按机会编号对我的要求进行分组，如下所示：

        List<Requirement> result = requirements
                                    .GroupBy(l => l.CRMOpportunityNumber)
                                    .Select(cl => new Requirement
                                    {
                                        CRMOpportunityNumber = cl.First().CRMOpportunityNumber,
                                        OpportunityTitle = cl.First().OpportunityTitle,
                                        ClientName = cl.First().ClientName,
                                        TentativeStartDate = cl.Min(c => c.TentativeStartDate),
                                        TotalPositions = cl.Sum(c => c.Required),
                                        RegionName = cl.First().RegionName,
                                        TotalCVProposed = cl.Sum(c => c.Associates.Count),
                                        TotalDeployed = cl.Sum(c => c.Associates.Count(x => x.IsIdentified == true)),
                                        NetGap = cl.Sum(c => c.Required) - cl.Sum(c => c.Associates.Count(x => x.IsIdentified == true)),
                                    }).OrderByDescending(l => l.CRMOpportunityNumber).ToList();

现在我不想在分组（结果）中包含所有 CATEGORY 字段值等于“工作开始”的要求。

需求类有一个字段类别。

【问题讨论】：

标签： c# linq group-by

【解决方案1】：

在分组前使用 Where 子句排除“已开始工作”类别

    List<Requirement> result = requirements
                                .Where(r => r.Category != "work commenced")
                                .GroupBy(l => l.CRMOpportunityNumber)
                                .Select(cl => new Requirement
                                {
                                    CRMOpportunityNumber = cl.First().CRMOpportunityNumber,
                                    OpportunityTitle = cl.First().OpportunityTitle,
                                    ClientName = cl.First().ClientName,
                                    TentativeStartDate = cl.Min(c => c.TentativeStartDate),
                                    TotalPositions = cl.Sum(c => c.Required),
                                    RegionName = cl.First().RegionName,
                                    TotalCVProposed = cl.Sum(c => c.Associates.Count),
                                    TotalDeployed = cl.Sum(c => c.Associates.Count(x => x.IsIdentified == true)),
                                    NetGap = cl.Sum(c => c.Required) - cl.Sum(c => c.Associates.Count(x => x.IsIdentified == true)),
                                }).OrderByDescending(l => l.CRMOpportunityNumber).ToList();

编辑

如果您想排除所有要求都属于“工作已开始”类别的组，该怎么办：

List<Requirement> result = requirements
    .GroupBy(l => l.CRMOpportunityNumber)
    .Where(cl => cl.All(l => l.Category != "work commenced"))
    .Select(cl => new Requirement
    {
        CRMOpportunityNumber = cl.First().CRMOpportunityNumber,
        OpportunityTitle = cl.First().OpportunityTitle,
        ClientName = cl.First().ClientName,
        TentativeStartDate = cl.Min(c => c.TentativeStartDate),
        TotalPositions = cl.Sum(c => c.Required),
        RegionName = cl.First().RegionName,
        TotalCVProposed = cl.Sum(c => c.Associates.Count),
        TotalDeployed = cl.Sum(c => c.Associates.Count(x => x.IsIdentified == true)),
        NetGap = cl.Sum(c => c.Required) - cl.Sum(c => c.Associates.Count(x => x.IsIdentified == true))
    }).OrderByDescending(l => l.CRMOpportunityNumber)
    .ToList();

【讨论】：

我认为这将排除“工作开始”的任何要求。我想排除那些所有分组要求的类别等于“工作开始”的分组要求。组内所有要求的类别不应该是“工作开始”
您的意思是仅当组中的每个需求都具有“开始工作”类别时才要排除组？

【解决方案2】：

如果该组中的所有项目的 CATEGORY 字段值等于“工作开始”，您希望排除该组。换句话说，如果组中的任何项目具有“工作开始”以外的值，则您希望包括该组。这可以使用 LINQ Any() 来实现，如下所示：

List<Requirement> result = 
                    requirements.GroupBy(l => l.CRMOpportunityNumber)
                                .Where(g => g.Any(item => item.Category != "work commenced")
                                .Select(cl => new Requirement
                                {
                                    ......
                                }).OrderByDescending(l => l.CRMOpportunityNumber)
                                .ToList();

【讨论】：