Question

让我说我有，

class Product
{
    public int Id {get; set;}
    public string Name {get; set;}
    public int Order {get; set;}
}

我的数据有，

products[0] = new Product { Id = 1, Name = "P1", Order = 1 }; 
products[1] = new Product { Id = 1, Name = "P2", Order = 2 }; 
products[2] = new Product { Id = 1, Name = null, Order = 3 }; 
products[3] = new Product { Id = 2, Name = "P3", Order = 4 }; 
products[4] = new Product { Id = 2, Name = null, Order = 5 }; 
products[5] = new Product { Id = 2, Name = null, Order = 6 };

我需要的是每个Product.Id的最后一个（按订单desc排序）不可为空的Name值。所以我的最终输出看起来像，

items[0] =  new { Id = 1, Name = "P2"}; 
items[1] =  new { Id = 2, Name = "P3"};

如果Id=1，我有3个姓名（P1，P2，null）和不可为空的姓名（P1，P2 ）但最后一个是P3。

Answer 1

这应该是最后的产品。

var lastOrders = products
        .Where(x => x.Name != null) // Remove inapplicable data
        .OrderBy(x => x.Order) // Order by the Order
        .GroupBy(x => x.Id) // Group the sorted Products
        .Select(x => x.Last()); // Get the last products in the groups

Answer 2

var result = products
              .GroupBy(p => p.Id)
              .Select(g => g.OrderBy(x => x.Order).Last(x => x.Name != null));

Answer 3

这将为您提供所需的输出：

If Mobile Then
    <input id="selling-date" type="date" placeholder="YYYY-MM-DD" max="2999-12-31" min="2010-01-01" value="2015-01-01" />
else
    <input id="selling-date" type="text" class="date-picker" readonly="readonly" placeholder="YYYY-MM-DD" max="2999-12-31" min="2010-01-01" value="2015-01-01" />

Answer 4

可以使用以下Linq语句解决该任务。

var Result = products.OrderBy().Where( null != iProduct.Name ).First();

这要求products至少包含Name为null的项目，否则将引发Exception。或者，

var Result = products.OrderBy().Where( null != iProduct.Name ).FirstOrDefault();

如果null不包含此类项目，

将返回products。

Answer 5

尝试：

var expectedProduct =products.Where(p => p.Id != null).OrderByDescending(p => p.Order).GroupBy(p => p.Id).Last()

选择每个产品的最后一个不可归零商品？

5 个答案: