Question

如何使用EF4在Select中检索元组？

        var productCount = (from product in context.products
                    select new Tuple<Product, int>(product, products.Orders.Count));

或者

        var productCount = (from product in context.products
                    select Tuple.Create(product, products.Orders.Count));

实体框架说第一种情况不能使用空构造函数，而不能识别第二种情况的Tuple.Create方法。

Answer 1

如何切换到投影的LINQ到对象：

var productCount = from product in context.products
                select new {Product = product, Count = products.Orders.Count };
var final = from item in productCount.AsEnumerable()
            select Tuple.Create(item.Product, item.Count);

Answer 2

尝试

 var productCount = from product in context.products 
                    select new { product, Count = products.Orders.Count };

这将返回一个非常接近元组的匿名类型 http://msdn.microsoft.com/en-us/library/bb738512.aspx

从EF select返回元组

2 个答案: