Question

I have the following query to start with:

var query = from p in db.Products
                        from pc in p.NpProductCategories
                        where pc.CategoryId == categoryId 
                        select p;

I m 对其应用一些更多的过滤器,最后,我想对结果进行分类:

if (orderBy == ProductSortingEnum.Name)
                    query = query.OrderBy(x => x.Name);
                else
                    query = query.OrderBy(............);

My big problem (coming from not knowing linq too good) is the ELSE here. How can I sort results by a column that is not in the current result set? I would like to somehow link to another linq query in the orderby. The sorting I m trying to achive is to link to NpProductVariants query using the ProductId to match between NpProductVariant and Products and sort by the Price of the NpProductVariant

Answer 1

Assuming you have the relationship set up in the dbml...

一至一(及多至一):

query = query.OrderBy(p => p.NpProductVariant.Price);

For one to many:

query = query.OrderBy(p => p.NpProductVariants.Select(v => v.Price).Max());

此外:

var query =
  from p in db.Products 
  where p.NpProductCategories.Any(pc => pc.CategoryId == categoryId)
  select p;

Answer 2

I think you can hook your Join to your query as long as it is returning the same thing. So maybe something like (I m not 100 % sure since I haven t tried it):

            query = from i1 in query
                 join i2 in query2 on i1.PropertyToJoin equals i2.PropertyToJoin
                 orderby i1.OrderProp1, i2.OrderProp2
                 select i1;

但是,我认为,检查所生成的钢.可能是一个好的想法,因此它依然有效。

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