如何从Linq查询中提取结果？

Question

class Program
{
    static void Main(string[] args)
    {
        MyDatabaseEntities entities = new MyDatabaseEntities();

        var result = from c in entities.Categories
                        join p in entities.Products on c.ID equals p.IDCategory
                        group p by c.Name into g
                        select new
                        {
                            Name = g.Key,
                            Count = g.Count()
                        };

        Console.WriteLine(result.ToString());
        Console.ReadLine();
    }
}

如何从结果集中提取值,以便我可以使用它们？

Answer 1

foreach (var item in result)
{
    var name = item.Name;
    var count = item.Count;
    ...
}

这只能在LINQ查询所在的同一方法内部工作,因为编译器只知道new { }LINQ中使用的匿名对象类型()中有哪些属性可用select.

如果将LINQ查询返回给调用方法,并且希望以上面显示的方式访问它,则必须定义显式类型并在LINQ查询中使用它:

class NameCountType
{
    public string Name { get; set; }
    public int Count { get; set; }
}

...

return from ... in ...
       ...
       select new NameCountType
              {
                  Name = ...,
                  Count = ...,
              };