Question

我有几个相关的表格(实体)。 I m试图利用下列支线使各实体受益:

ObjectQuery<Location> locations = context.Location;
ObjectQuery<ProductPrice> productPrice = context.ProductPrice;
ObjectQuery<Product> products = context.Product;
IQueryable<ProductPrice> res1 = from pp in productPrice
                    join loc in locations
                    on pp.Location equals loc
                    join prod in products
                    on pp.Product equals prod
                    where prod.Title.ToLower().IndexOf(Word.ToLower()) > -1
                    select pp;

查询记录2 产品目标与产品挂钩,但无效,我无法理解原因。如果我试图在小组中填满如下:

res =
                from pp in productPrice
                join loc in locations
                on pp.Location equals loc
                join prod in products
                on pp.Product equals prod
                where prod.Title.ToLower().IndexOf(Word.ToLower()) > -1
                select new ProductPrice
                {
                    ProductPriceId = pp.ProductPriceId,
                    Product = prod
                };

I have the exception "The entity or complex type PBExplorerData.ProductPrice cannot be constructed in a LINQ to Entities query" Could someone please explain me what happens and what I need to do? Thanks

Answer 1

回答你的第一个问题,即产品与地点是无效的,因为你需要在你的询问中添加一个“包含”的内容。

  IQueryable<ProductPrice> res1 = from pp in 
                productPrice.Include("Location").Include("Product")
                  join loc in locations
                    on pp.Location equals loc
                  join prod in products
                    on pp.Product equals prod
                  where prod.Title.ToLower().IndexOf(Word.ToLower()) > -1
                select pp;

第二个问题是欧洲法院试图推翻你的询问和产品价格(不是实体),以便它无法做到。如果你想把它变成匿名的一类,那么这样做就是

            select new 
            {
                ProductPriceId = pp.ProductPriceId,
                Product = prod
            };

之后

          res.ToList().ConvertAll(x=new ProductPrice () {
               ProductPriceId  = x.ProductPriceId ,
               Product  = x.Product

           });

或者,你可以采取其他方式,选择你想要的实体,并仅用人手。

友情链接