我正在尝试遍历下面的 XML,并找到entry
底层category
元素具有collection
thrterm
属性值的所有元素。以下示例中有 2 个。然后对于那些获取元素href
属性的值。link
但是,我似乎找不到正确的选择器:
<feed xmlns="http://www.w3.org/2005/Atom">
<title>demo</title>
<id>urn:uuid:071d9650-ae6c-11e7-8f1a-0800200c9a66</id>
<link rel="self" href="https://test.com/atom/index.xml"/>
<updated>2017-10-11T14:37:33+02:00</updated>
<author>
<name>Test</name>
<uri>http://www.test.com</uri>
</author>
<generator version="1.8">Agent</generator>
<entry>
<title>YDEMO</title>
<id>urn:uuid:15f44340-ae6c-11e7-8f1a-0800200c9a66</id>
<category term="collection"/>
<published>2017-10-11T13:41:53+02:00</published>
<updated>2017-10-11T14:37:33+02:00</updated>
<link rel="alternate" href="https://www.myurl.com" type="text/xml"/>
<mcp:projectScenario xmlns:mcp="http://webservice.yes-co.nl/3mcp/1.5/atom-extension">NBvh</mcp:projectScenario>
</entry>
<entry>
<title>DEMO 2</title>
<id>urn:uuid:25f44340-ae6c-11e7-8f1a-0800200c9a00</id>
<category term="collection"/>
<published>2017-10-11T13:42:53+02:00</published>
<updated>2017-10-11T14:38:33+02:00</updated>
<link rel="alternate" href="https://www.myurl2.com" type="text/xml"/>
<mcp:projectScenario xmlns:mcp="http://webservice.yes-co.nl/3mcp/1.5/atom-extension">BBvh</mcp:projectScenario>
</entry>
<entry>
<title>photo</title>
<id>12</id>
<category term="metadata"/>
<updated>2016-10-11T14:38:33+02:00</updated>
<link rel="alternate" href="https://www.myurl2.com" type="text/xml"/>
</entry>
<entry
xmlns:mcp="http://webservice.yes-co.nl/3mcp/1.5/atom-extension">
<title>No title</title>
<id>urn:uuid:6d65c57f-621f-4c15-8a1d-5dc967423d5d</id>
<category term="media"/>
<published>2017-10-11T13:39:43+02:00</published>
<updated>2017-10-11T13:39:43+02:00</updated>
<link
xmlns:mcp="http://webservice.yes-co.nl/3mcp/1.5/atom-extension" rel="related" href="https://webservice.yes-co.com/3mcp/1.5/15f44340-ae6c-11e7-8f1a-0800200c9a66/media/6d65c57f-621f-4c15-8a1d-5dc967423d5d-large.jpg" type="image/jpg" mcp:mediaFormat="large"/>
</entry>
</feed>
到目前为止,这是我的代码,但即使data
变量包含上面的 XML,该nodeList.Count
行也会返回 0 个结果:
Dim WC As New WebClient
Dim data As String = WC.DownloadString("http://localhost/index.xml")
Dim indexXML As New XmlDocument
indexXML.LoadXml(data)
Dim mgr As XmlNamespaceManager = New XmlNamespaceManager(indexXML.NameTable)
mgr.AddNamespace("http://www.w3.org/2005/Atom", indexXML.DocumentElement.NamespaceURI)
Dim node As XmlNode
Dim root As XmlNode = indexXML.DocumentElement
Dim nodeList As XmlNodeList = root.SelectNodes("/feed/entry")
'now loop through all elements with "category term=collection" in index.xml
For i As Integer = 0 To nodeList.Count - 1
If nodeList(i).SelectSingleNode("/category/@term=collection") IsNot Nothing Then
LogMessage(nodeList(i).SelectSingleNode("/category/link/@href").Value)
End If
Next i
更新 1
我想选择所有具有类别节点的“条目”元素term=collection
。该部分通过以下语句起作用:indexXML.SelectNodes("/atom:feed/atom:entry[atom:category/@term=""collection""]", mgr)
我想从入口节点开始,然后我想选择入口的子元素链接的 href 属性(以及将来的其他子元素entry
。但是,我在下面尝试的示例都没有返回href
属性的值。如何我可以解决吗?
我现在有这个:
Dim mgr As XmlNamespaceManager = New XmlNamespaceManager(indexXML.NameTable)
mgr.AddNamespace("atom", "http://www.w3.org/2005/Atom")
Dim root As XmlNode = indexXML.DocumentElement
Dim nodeList As XmlNodeList = indexXML.SelectNodes("/atom:feed/atom:entry[atom:category/@term=""collection""]", mgr)
'now loop through all collections in index.xml
For i As Integer = 0 To nodeList.Count - 1 '1 result found
'NONE OF CALLS BELOW RETURN THE VALUE OF HREF ATTRIBUTE
If nodeList(i).SelectSingleNode("atom:/link/@href", mgr) IsNot Nothing Then
LogMessage(nodeList(i).SelectSingleNode("atom:/link/@href", mgr).Value)
'error: 'atom:/link/@href' has an invalid qualified name.
End If
Next i
更新 2
感谢@Pawel,我能够选择所有entry
节点作为节点属性的project
值,如下所示:term
category
objectsXML.SelectNodes("/atom:feed/atom:entry[atom:category/@term=""project""]", mgr)
但是,如何向此选择器添加额外的标准以过滤掉entry
具有值NBvh
ORBBvh
的节点mcp:projectScenario
?
更新 3 我向管理器添加了一个额外的命名空间:
mgr.AddNamespace("atom", "http://www.w3.org/2005/Atom")
mgr.AddNamespace("mcp", "http://webservice.yes-co.nl/3mcp/1.5/atom-extension")
但是当我尝试href
通过 uuid 选择媒体元素的属性时,我得到了错误:Object reference not set to an instance of an object.
我的代码:
objectsXML.SelectSingleNode("/atom:feed/atom:entry[atom:id=""urn:uuid:" + "6d65c57f-621f-4c15-8a1d-5dc967423d5d" + """]/mcp:link/@href", mgr).InnerText