Question

我正在开发asp.net核心应用程序。我有以下linq查询，用于填充模型。此模型具有属性qtryregions，这是一个列表。如何在一个查询中填写它。

keras

我不想使用上面的foreach并希望在第一个linq查询中填充product.Qtyregion。

请建议。

Answer 1

这是你想要的吗？

Products = (
    from d in db.PODetails
    join p in db.Products on d.ProductID equals p.ProductID
    where d.POID == id
    select new PODetailsFull
    {
        PODetailID = d.PODetailID,

        //QtyRegion = new List<string>() { Region.Region + " " + POAllocation.Allocate != null ? POAllocation.Allocate.ToString() : "" },                 
        Sku = p.Sku,
        Cntnr20 = p.Cntnr20 ?? 0,
        Cntnr40 = p.Cntnr40 ?? 0,
        Cntnr40HQ = p.Cntnr40HQ ?? 0,
        QtyRegion = (
            from POAllocation in db.POAllocations.Where(p => p.PODetailID == d.PODetailID)
            join regions in db.Regions on POAllocation.RegionID equals regions.RegionID
            select regions.Region + " " + POAllocation.Allocate ?? "").ToList(),
    }).ToList();

Answer 2

尝试使用分组依据来避免N + 1查询问题：

Products = (
from d in db.PODetails
join p in db.Products on d.ProductID equals p.ProductID
join palloc in db.POAllocations on d.PODetailID equals palloc.PODetailID
group by new { 
    PODetailID = d.PODetailID,         
    Sku = p.Sku,
    Cntnr20 = p.Cntnr20,
    Cntnr40 = p.Cntnr40,
    Cntnr40HQ = p.Cntnr40HQ }
into grp
where grp.Key.POID == id
select new PODetailsFull
{
    PODetailID = grp.Key.PODetailID,

    QtyRegion = grp,                 
    Sku = grp.Key.Sku,
    Cntnr20 = grp.Key.Cntnr20 ?? 0,
    Cntnr40 = grp.Key.Cntnr40 ?? 0,
    Cntnr40HQ = grp.Key.Cntnr40HQ ?? 0
}).ToList();

如何在C＃中使用linq填充模型列表

2 个答案: