Linq连接组按条件选择不同类型的对象

Question

我正在通过linq和lambda表达式对两个集合进行分组。

        var result = firstCollection.GroupJoin(secondCollection,
            s => s.Id,
            p => p.Sid,
            (first, second) =>
            {
                return new { first.Id };
            });

这很有效。但我想按照这样的条件选择：

        var result = firstCollection.GroupJoin(secondCollection,
            s => s.Id,
            p => p.Sid,
            (first, second) =>
            {
                if (someCondition)
                    return new { id = first.Id };
                else
                    return new { 
                          id = first.Id, 
                          name = first.Name };
            });

但这会给出错误。我怎么能这样做？

Answer 1

是的，你可以这样，

 var result = firstCollection.GroupJoin(secondCollection,
            s => s.Id,
            p => p.Sid,
            (first, second) =>
            {
                dynamic foo;
                if (someCondition)
                    foo = new { id = first.Id };
                else
                    foo = new { 
                          id = first.Id, 
                          name = first.Name 
                    };

                return foo;
            });