Question

给出以下代码：

var people = new List<person>(){ new person { Name = "John", FamilyName = "Pendray" },
             new person { FamilyName = "Emery", Name = "Jake"},
             new person { FamilyName = "Pendray", Name = "Richard" } };

var q = from p in people
                 orderby p.Name
                 group p by p.FamilyName into fam
                 orderby fam.Key
                 select new { fam.Key, members = from p in fam select p };

是否可以使用将输出IEnumerable <string＆gt;的选择替换最后一行？包含这两个字符串： “Pendray John Richard” “Emery Jake”？是否可以将linq查询投影到这样的字符串中？

编辑：我知道这可以通过更多代码实现，但我感兴趣的是，这是否可以在linq查询本身内完成，类似于VB能够从查询中调出xml，如{{3 （特别是本页的最后一个代码块）

Answer 1

var q = from p in people
        orderby p.Name
        group p by p.FamilyName into fam
        orderby fam.Key
        select fam.Key + " " + string.Join(" ", (from fm in fam select fm.Name).ToArray());

返回

Emery Jake
Pendray John Richard

Answer 2

当然。

您必须更改选择部分。最简单的方法是定义一个函数，该函数将获取IEnumerable并生成该字符串，然后调用该函数

people = new List<person>(){ new person { Name = "John", FamilyName = "Pendray" },
         new person { FamilyName = "Emery", Name = "Jake"},
         new person { FamilyName = "Pendray", Name = "Richard" } };

var q = from p in people
        orderby p.Name
        group p by p.FamilyName into fam
        orderby fam.Key
        select new { Key = fam.Key, Text = GetText(fam) };



// and elsewhere...
private string GetText(IEnumerable<person> family) {
    string result = "Whatever"; // build the result string here
    return result;
}

此外，如果您只想要文本，则可以将查询的最后一行更改为

        select GetText(fam);

从Grouping Linq Query生成字符串

2 个答案: