实体框架-有条件地将列添加到分组依据 [英] Entity Framework - Conditionally adding columns into group by

问题描述

我想有条件地将列添加到GroupBy子句中，但是我不确定该怎么做.

I want to conditionally add columns into GroupBy clause but I am not sure how it can be done.

我有5列，我想根据用户的输入按语句添加到组中.为此，我具有以下属性:

I have 5 columns which I want to add in group by statement depending upon user's input. To do this I have following properties:

ProductId
ColorId
PieceId
SizeId
WeightId

如果任何属性的值大于0，则需要在group by子句中使用此列.

If any property has value greater than 0 then this column needs to be used in group by clause.

因此，如果ProductId，ColorId和PieceId的值大于0，则在分组依据中应存在以下值:

So if ProductId, ColorId and PieceId has value greater than 0 than following should be there in group by:

list.GroupBy(p => new { p.Product.Id, p.ColorId, p.PieceId });

推荐答案

尝试类似方法；

var groupedList = list.GroupBy(p => new
{
    ProductId = p.Product.Id > 5 ? p.Product.Id : (int?)null,
    ColorId = p.ColorId > 5 ? p.ColorId : (int?)null,
    PieceId = p.PieceId > 5 ? p.PieceId : (int?)null
})
.Select(x =>
new
{
    x.Key.ProductId,
    x.Key.ColorId,
    x.Key.PieceId
}).ToList();

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