Groupby 使用动态 linq

Question

谁能帮我完成这项工作？

我有以下代码：

dt.Columns.Add("Field1", typeof(String));
dt.Columns.Add("Field2", typeof(String));
dt.Columns.Add("NR", typeof(Double));

dt.Rows.Add("A", "990001", 100);
dt.Rows.Add("A", "990001", 120);
dt.Rows.Add("B", "990001", 200);
dt.Rows.Add("B", "990001", 300);

var fields = new List<string>() { "Field1", "Field2" };

var q = dt.AsEnumerable().AsQueryable()
          .GroupBy("new(" +  qfields + ")", "it")
          .Select("new(Key as Group, Sum(NR) as Tot)");

当我执行这段代码时，我得到了错误：

“DataRow”类型中不存在属性或字段“NR”

我需要结果为：

A, 990001, 220
B, 990001, 500

Answer 1

var q =
    dt.AsEnumerable()
        .AsQueryable()
        .GroupBy("new(it[\"Field1\"] as Field1,it[\"Field2\"]as Field2)", "it")
        .Select("new(Key as Group, Sum(double(it[\"NR\"])) as Tot)");
foreach (var v in q)
{
    Console.WriteLine(v);
}