linq to XML:文档中的多个节点/值查询 [英] linq to XML: multiple node/value queries in a document
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问题描述
您好！
我想到了另一个问题，因为这是获得答案的最佳位置，所以我在这里尝试(嘿，这真是个夸奖！).
因此，我可以从XML文件中查询节点/值组合:
public FileInfo ReadXML(FileInfo fInfo, string node, string value)
{ <br /> XDocument xmlFile = XDocument.Load(fInfo.FullName); <br />var query = (from p in xmlFile.Descendants(node)<br /> where p.Value.Contains(value)<br /> select p).ToArray(); <br /> if (query.Count() != 0) <br /> return fInfo;
}
但是，如果我有两个节点/值，应该是什么样子我必须查询的组合.
例如:名字必须是Franz并且他必须在加拿大出生
名字必须是Franz或Person必须在加拿大出生
一如既往地感谢提前，
eza
(这是一篇双重帖子，但我首先错过了这个论坛)
解决方案
在这种情况下，您无法查看单个后代，但是您需要分别搜索父"节点，然后查询其后代.
示例:给定文件
<br /><?xml version="1.0" encoding="utf-8" ?><br /><people><br /> <person><br /> <name>Franz</name><br /> <country>Canada</country><br /> </person><br /> <person><br /> <name>Franz</name><br /> <country>Germany</country><br /> </person><br /> <person><br /> <name>Bob</name><br /> <country>Canada</country><br /> </person><br /> <person><br /> <name>Mike</name><br /> <country>UK</country><br /> </person><br /> <person><br /> <name>Alan</name><br /> <country>Germany</country><br /> </person><br /></people>
首先，构建人"节点的列表以获取容器".然后，您可以在每个节点上进行子查询，以查找子元素.
<br /> var doc = XDocument.Load("XMLFile1.xml");<br /><br /> // select the nodes of type person<br /> var nodes = from n in doc.Descendants("person") select n;<br /><br /> // get EITHER Franz or Canada<br /> var FranzORCanada = from n in nodes<br /> where ((from x in n.Descendants("name") where x.Value == "Franz" select x).Count() > 0)<br /> || ((from y in n.Descendants("country") where y.Value == "Canada" select y).Count() > 0)<br /> select n;<br /><br /> Console.WriteLine("FRANZ or CANADA");<br /> Console.WriteLine("---------------");<br /> foreach (var node in FranzORCanada)<br /> {<br /> Console.WriteLine("{0} - {1}", node.Descendants("name").First().Value, node.Descendants("country").First().Value);<br /> }<br /> Console.WriteLine();<br /><br /> // get nodes with Franz AND Canada<br /> var FranzANDCanada = from n in nodes<br /> where ((from x in n.Descendants("name") where x.Value == "Franz" select x).Count() > 0)<br /> && ((from y in n.Descendants("country") where y.Value == "Canada" select y).Count() > 0)<br /> select n;<br /><br /> Console.WriteLine("FRANZ and CANADA");<br /> Console.WriteLine("----------------");<br /> foreach (var node in FranzANDCanada)<br /> {<br /> Console.WriteLine("{0} - {1}", node.Descendants("name").First().Value, node.Descendants("country").First().Value);<br /> }<br /><br /><br /> Console.ReadKey();<br />
这将产生以下结果:
<br />FRANZ or CANADA<br />---------------<br />Franz - Canada<br />Franz - Germany<br />Bob - Canada<br /><br />FRANZ and CANADA<br />----------------<br />Franz - Canada<br />
Hi again!
Qnother question comes to my mind and since this is the best place to get an answer, I''m trying it here (hey, that''s been a compliment!).
So I can query a node/value combination from a XML file:
public FileInfo ReadXML(FileInfo fInfo, string node, string value)
{ <br /> XDocument xmlFile = XDocument.Load(fInfo.FullName); <br />var query = (from p in xmlFile.Descendants(node)<br /> where p.Value.Contains(value)<br /> select p).ToArray(); <br /> if (query.Count() != 0) <br /> return fInfo;
}
but how this should look like if I have for instance two node/value combinations I have to query for.
E.g: Name has to be Franz AND he needs to be born in Canada
Name has to be either Franz or the Person has to be born in CANADA
As always thanks in advance,
eza
(this is a double post, but I missed this forum in the first place)
解决方案
In this case you cannot look at the individual descendants but you need to search the "parent" nodes individually, and then query their descendants.
Example: given the file<br /><?xml version="1.0" encoding="utf-8" ?><br /><people><br /> <person><br /> <name>Franz</name><br /> <country>Canada</country><br /> </person><br /> <person><br /> <name>Franz</name><br /> <country>Germany</country><br /> </person><br /> <person><br /> <name>Bob</name><br /> <country>Canada</country><br /> </person><br /> <person><br /> <name>Mike</name><br /> <country>UK</country><br /> </person><br /> <person><br /> <name>Alan</name><br /> <country>Germany</country><br /> </person><br /></people>
First you build a list of the "person" node to get the ''container''. Then you can do a sub-query on each node, looking for the child elements.<br /> var doc = XDocument.Load("XMLFile1.xml");<br /><br /> // select the nodes of type person<br /> var nodes = from n in doc.Descendants("person") select n;<br /><br /> // get EITHER Franz or Canada<br /> var FranzORCanada = from n in nodes<br /> where ((from x in n.Descendants("name") where x.Value == "Franz" select x).Count() > 0)<br /> || ((from y in n.Descendants("country") where y.Value == "Canada" select y).Count() > 0)<br /> select n;<br /><br /> Console.WriteLine("FRANZ or CANADA");<br /> Console.WriteLine("---------------");<br /> foreach (var node in FranzORCanada)<br /> {<br /> Console.WriteLine("{0} - {1}", node.Descendants("name").First().Value, node.Descendants("country").First().Value);<br /> }<br /> Console.WriteLine();<br /><br /> // get nodes with Franz AND Canada<br /> var FranzANDCanada = from n in nodes<br /> where ((from x in n.Descendants("name") where x.Value == "Franz" select x).Count() > 0)<br /> && ((from y in n.Descendants("country") where y.Value == "Canada" select y).Count() > 0)<br /> select n;<br /><br /> Console.WriteLine("FRANZ and CANADA");<br /> Console.WriteLine("----------------");<br /> foreach (var node in FranzANDCanada)<br /> {<br /> Console.WriteLine("{0} - {1}", node.Descendants("name").First().Value, node.Descendants("country").First().Value);<br /> }<br /><br /><br /> Console.ReadKey();<br />
This produces the following:<br />FRANZ or CANADA<br />---------------<br />Franz - Canada<br />Franz - Germany<br />Bob - Canada<br /><br />FRANZ and CANADA<br />----------------<br />Franz - Canada<br />
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