Question

鉴于以下查询

       public TrainingListViewModel(List<int> employeeIdList)
        {
            this.EmployeeOtherLeaveItemList =
                CacheObjects.AllEmployeeOtherLeaves
                .Where(x => x.OtherLeaveDate >= Utility.GetToday() &&
                    x.CancelDate.HasValue == false &&
                    x.OtherLeaveId == Constants.TrainingId)
                .OrderBy(x => x.OtherLeaveDate)
                .Select(x => new EmployeeOtherLeaveItem
                {
                    EmployeeOtherLeave = x,
                    SelectedFlag = false
                }).ToList();
        }

我想将employeeIdList放入查询中。我想检索所有x.OtherLeaveDate值，其中每个连接都存在相同的x.OtherLeaveDate，其中x.EmployeeId =（employeeIdList中的int employeeId）

例如，如果employeeIdList和CacheObjects.AllEmployeeOtherLeaves集合中有EmployeeIds 1,2,3，则所有3名员工的日期为1/1/2001，然后检索该日期。

Answer 1

如果我读得很好，那应该是

var grp = this.EmployeeOtherLeaveItemList =
    CacheObjects.AllEmployeeOtherLeaves
    .Where(x => x.OtherLeaveDate >= Utility.GetToday()
             && x.CancelDate.HasValue == false
             && x.OtherLeaveId == Constants.TrainingId
             && employeeIdList.Contains(x.EmployeeId)) // courtesy @IronMan84
    .GroupBy(x => x.OtherLeaveDate);

if (grp.Count() == 1)
{
    var result = g.First().Select(x => new EmployeeOtherLeaveItem
    {
        EmployeeOtherLeave = x,
        SelectedFlag = false
    })
}

首先，数据按OtherLeaveDate分组。如果分组只生成一个组，则会采用第一个（也是唯一的）IGrouping实例（这是Leave个对象的列表），并将其内容投影到EmployeeOtherLeaveItem。< / p>

Answer 2

在where语句中添加“＆amp;＆amp; employeeIdList.Contains（x.EmployeeId）”

Answer 3

我要感谢@ IronMan84和@GertArnold帮助我，并且我必须告诫自己，因为我没有更清楚这个问题。这是我想出的答案。毫无疑问，它可以得到改善，但鉴于没有人回答说我为什么现在打勾这个答案。

   var numberOfEmployees = employeeIdList.Count;


var grp = CacheObjects.AllEmployeeOtherLeaves.Where(
                    x =>
                    x.OtherLeaveDate >= Utility.GetToday() 
                    && x.CancelDate.HasValue == false
                    && x.OtherLeaveId == Constants.TrainingId 
                    && employeeIdList.Contains(x.EmployeeId))
                    .GroupBy(x => x.OtherLeaveDate)
                    .Select(x => new { NumberOf = x.Count(), Item = x });

            var list =
                grp.Where(item => item.NumberOf == numberOfEmployees).Select(item => item.Item.Key).ToList();

实体框架/ Linq - groupby和having子句

3 个答案: