小编Fra*_*k B的帖子

我正在尝试使用linq从EF Core数据集中过滤某些行，但我不明白为什么过滤IEnumerable与过滤IQueryable会给我带来不同的结果。

        var query = _db.Jobs
            .IsDelivered()
            .Include(a => a.JobExtras)
            .Include(a => a.Tips)
            .Include(a => a.Payments)
            .HasPayments();

        var query1 = query
            .ToList()
            .Where(a => a.Payments.Sum(b => b.Amount)
                         - a.Price.Value
                         - a.Discount
                         - a.JobExtras.Sum(c => c.Price)
                         - a.Tips.Sum(d => d.Amount)
                         > 0);

        var query2 = query
           .Where(a => a.Payments.Sum(b => b.Amount)
                         - a.Price.Value
                         - a.Discount
                         - a.JobExtras.Sum(c => c.Price)
                         - a.Tips.Sum(d => d.Amount)
                         > 0);

        Debug.WriteLine($"Record Count[Before Where Clause]: {query.Count()}");
        Debug.WriteLine($"Record Count[ToList() version]: {query1.Count()}");
        Debug.WriteLine($"Record Count[w/out ToList()]: {query2.Count()}");

这是输出：

Record Count[Before …

我确信对此有一个简单的答案，但我似乎无法确定。

我有以下代码，

internal override async Task FetchDataModel()
{
    var dateCutoff = DateTime.Today.AddDays(-PeriodInDays);

     var query = this.DB.Jobs
         .IsDelivered()
         .Where(x => x.DeliveredTime.Value.Date >= dateCutoff)
         .GroupBy(x => new { x.Pet.OwnerId, x.Pet.Owner.First, x.Pet.Owner.Last })
         .Select(x => new MVPCustomerDTO
         {
             OwnerId = x.Key.OwnerId,
             OwnerName = $"{x.Key.First} {x.Key.Last}",
             JobCount = x.Count(),
             TotalSpend = x.Sum(a => (a.Price ?? 0M) - a.Discount) 
                      + this.DB.JobExtras
                               .Where(a => a.Job.Pet.OwnerId == x.Key.OwnerId)
                               .Where(a => a.Job.DeliveredTime.Value.Date >= dateCutoff)
                               .Sum(a => a.Price),
         })
/*==>Problem Line*/ .OrderByDescending(x => x.TotalSpend)
         .Take(25);

          var result = await …