c# – 为什么LINQ无法将DataRows添加到DataTable？

将ExpandoObjects鞋拔成网格,就像下面的两次尝试一样.

这不起作用：

var data = _d.Query<dynamic>(_script);         // returns IEnumerable<ExpandoObject>

IDictionary<string,object> c = (IDictionary<string,object>)data.FirstOrDefault();
DataTable dt = new DataTable();

dt.BeginLoadData();
dt.Columns.AddRange(c.Keys.Select(k => new DataColumn(k)).ToArray());
data.Select(r => dt.Rows.Add((r as IDictionary<string,object>).Values.ToArray()));
dt.EndLoadData();

但这样做：

dt.Columns.AddRange(c.Keys.Select(k => new DataColumn(k)).ToArray());
foreach (IDictionary<string,object> r in data)
  dt.Rows.Add(r.Values.ToArray());

为什么？

解决方法

选择方法

The query represented by this method is not executed until the object
is enumerated either by calling its GetEnumerator method directly or
by using foreach in Visual C# or For Each in Visual Basic.

所以这个选择永远不会执行：

data.Select(r => dt.Rows.Add((r as IDictionary<string,object>).Values.ToArray()));

参考http://msdn.microsoft.com/ru-ru/library/bb548891.aspx