HOW TO：篩選屬性 (XPath - LINQ to XML)
本主題顯示如何取得具有指定之名稱以及具有指定值之屬性的子代項目。
XPath 運算式為：
.//Address[@Type='Shipping']
範例
此範例會尋找具有 Address 之名稱，以及具有值為 "Shipping" 之 Type 屬性的所有子代項目。
此範例使用下列 XML 文件：XML 範例檔：多個採購訂單 (LINQ to XML)。
XDocument po = XDocument.Load("PurchaseOrders.xml");
// LINQ to XML query
IEnumerable<XElement> list1 =
from el in po.Descendants("Address")
where (string)el.Attribute("Type") == "Shipping"
select el;
// XPath expression
IEnumerable<XElement> list2 = po.XPathSelectElements(".//Address[@Type='Shipping']");
if (list1.Count() == list2.Count() &&
list1.Intersect(list2).Count() == list1.Count())
Console.WriteLine("Results are identical");
else
Console.WriteLine("Results differ");
foreach (XElement el in list1)
Console.WriteLine(el);
Dim po As XDocument = XDocument.Load("PurchaseOrders.xml")
' LINQ to XML query
Dim list1 As IEnumerable(Of XElement) = _
From el In po...<Address> _
Where el.@Type = "Shipping" _
Select el
' XPath expression
Dim list2 As IEnumerable(Of XElement) = _
po.XPathSelectElements(".//Address[@Type='Shipping']")
If (list1.Count = list2.Count And _
list1.Intersect(list2).Count() = list1.Count()) Then
Console.WriteLine("Results are identical")
Else
Console.WriteLine("Results differ")
End If
For Each el As XElement In list1
Console.WriteLine(el)
Next
這個範例產生下列輸出：
Results are identical
<Address Type="Shipping">
<Name>Ellen Adams</Name>
<Street>123 Maple Street</Street>
<City>Mill Valley</City>
<State>CA</State>
<Zip>10999</Zip>
<Country>USA</Country>
</Address>
<Address Type="Shipping">
<Name>Cristian Osorio</Name>
<Street>456 Main Street</Street>
<City>Buffalo</City>
<State>NY</State>
<Zip>98112</Zip>
<Country>USA</Country>
</Address>
<Address Type="Shipping">
<Name>Jessica Arnold</Name>
<Street>4055 Madison Ave</Street>
<City>Seattle</City>
<State>WA</State>
<Zip>98112</Zip>
<Country>USA</Country>
</Address>