在Linq中为对象分配不同的对象/类

Question

我正在做下面的事情，它工作了:

    var resultsHeader = (from r in o select new { 
                        OrderID  = r.OrderID,
                        subtotal = r.SubTotal,
                        city = r.orderAddress.BilltoCity
    }).Distinct().ToList();

看city = r.orderAddress。BilltoCity Line，是否有任何方法可以填充整个对象…这样的

var resultsHeader = (from r in o select new { 
                    OrderID  = r.OrderID,
                    subtotal = r.SubTotal,
                    Address = r.orderAddress
}).Distinct().ToList();

基本上，我想将整个OrderAddress对象存储到Address属性中，但是它不作为Distinct对象。

Answer 1

您可以使用DistinctBy from moreLINQ:

var resultsHeader = (from r in o select new { 
                    OrderID  = r.OrderID,
                    subtotal = r.SubTotal,
                    city = r.orderAddress.BilltoCity
}).DistinctBy(x => new { x.OrderID, x.subtotal }).ToList();

或GroupBy，它已经是LINQ的一部分:

var resultsHeader = (from r in o
                     group r by new { r.OrderIs, r.SubTotal } into g
                     select new {
                         g.Key.OrderID,
                         g.Key.SubTotal,
                         Address = g.First().orderAddress
                     }).ToList()

或者，您可以在Address类上实现Equals和GetHashCode，并像现在一样使用Distinct。