LINQ to Entities选择具有表达式参数的列 [英] LINQ to Entities select columns with expression parameter
问题描述
我无法确定如何通过将表达式指定为参数来选择可查询的列.
I cannot wrap my head around how i manage to select columns in a queryable by specifying an expression as a parameter.
Method A(IQueryable<Order> query)
内部方法A我想指定要选择的列,所以我不会马上得到所有列,就像这样:
Inside Method A i want to specify which columns to select, so i dont get all columns right away, like this:
query.Select(x => new { x.OrderNumber, x.Payment, x.Customer })
如果我直接在方法A中指定它,这很容易,但是我想使用参数传递信息. 我尝试使用这样的表达式:
This is easy if i specify this directly in Method A, but i want to pass the information using a parameter. I tried using a expression like this:
Expression<Func<Order, dynamic>> columns
但是我无法使它正常工作,因为我只能指定一个列,在其中调用方法A,如下所示:
But i can't get it to work, since i can only specify one columns, where i call Method A, like this:
MethodA(query, (x) => x.OrderNumber);
如何指定多个属性?
推荐答案
我找到了解决方案. 我只需要指定这样的匿名类型:
I found the solution. I simply had to specify an anonymous type like this:
MethodA(query, order => new { order.OrderNumber, order.Payment })
现在我可以通过其他方法传递我的Select表达式.
Now i can pass in my Select expression from other methods.
这篇关于LINQ to Entities选择具有表达式参数的列的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!