我如何使用c#和LINQ提取XML深处的信息
本文关键字：XML 深处 信息 提取 LINQ 何使用 | 更新日期: 2023-09-27 17:53:25
这是我在StackOverflow上的第一篇文章，所以请原谅我。如果我的代码示例有点长，我先道歉。
使用c#和LINQ，我试图在一个更大的XML文件中识别一系列第三级id元素(000049)。每个第三级id都是唯一的，我想要的是基于每个级别的一系列后代信息。更具体地说，如果type == A和location type(old) == vault和location type(new) == out，那么我想选择id。下面是我使用的XML和c#代码。
总的来说，我的代码可以工作。如下所示，它将两次返回000049的id，这是正确的。然而，我发现了一个小故障。如果我删除包含type == A的第一个history块，我的代码仍然返回000049的id两次，而它应该只返回一次。我知道为什么会发生这种情况，但我想不出更好的方法来运行查询。是否有更好的方法来运行我的查询，以获得我想要的输出，仍然使用LINQ?
我的XML:
<?xml version="1.0" encoding="ISO8859-1" ?>
<data type="historylist">
<date type="runtime">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
<hour>15</hour>
<minutes>24</minutes>
<seconds>46</seconds>
</date>
<customer>
<id>0001</id>
<description>customer</description>
<mediatype>
<id>kit</id>
<description>customer kit</description>
<volume>
<id>000049</id>
<history>
<date type="optime">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
<hour>03</hour>
<minutes>00</minutes>
<seconds>02</seconds>
</date>
<userid>batch</userid>
<type>OD</type>
<location type="old">
<repository>vault</repository>
<slot>0</slot>
</location>
<location type="new">
<repository>out</repository>
<slot>0</slot>
</location>
<container>0001.kit.000049</container>
<date type="movedate">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
</date>
</history>
<history>
<date type="optime">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
<hour>06</hour>
<minutes>43</minutes>
<seconds>33</seconds>
</date>
<userid>vaultred</userid>
<type>A</type>
<location type="old">
<repository>vault</repository>
<slot>0</slot>
</location>
<location type="new">
<repository>out</repository>
<slot>0</slot>
</location>
<container>0001.kit.000049</container>
<date type="movedate">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
</date>
</history>
<history>
<date type="optime">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
<hour>06</hour>
<minutes>43</minutes>
<seconds>33</seconds>
</date>
<userid>vaultred</userid>
<type>S</type>
<location type="old">
<repository>vault</repository>
<slot>0</slot>
</location>
<location type="new">
<repository>out</repository>
<slot>0</slot>
</location>
<container>0001.kit.000049</container>
<date type="movedate">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
</date>
</history>
<history>
<date type="optime">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
<hour>06</hour>
<minutes>45</minutes>
<seconds>00</seconds>
</date>
<userid>batch</userid>
<type>O</type>
<location type="old">
<repository>out</repository>
<slot>0</slot>
</location>
<location type="new">
<repository>site</repository>
<slot>0</slot>
</location>
<container>0001.kit.000049</container>
<date type="movedate">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
</date>
</history>
<history>
<date type="optime">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
<hour>11</hour>
<minutes>25</minutes>
<seconds>59</seconds>
</date>
<userid>ihcmdm</userid>
<type>A</type>
<location type="old">
<repository>out</repository>
<slot>0</slot>
</location>
<location type="new">
<repository>site</repository>
<slot>0</slot>
</location>
<container>0001.kit.000049</container>
<date type="movedate">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
</date>
</history>
<history>
<date type="optime">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
<hour>11</hour>
<minutes>25</minutes>
<seconds>59</seconds>
</date>
<userid>ihcmdm</userid>
<type>S</type>
<location type="old">
<repository>out</repository>
<slot>0</slot>
</location>
<location type="new">
<repository>site</repository>
<slot>0</slot>
</location>
<container>0001.kit.000049</container>
<date type="movedate">
<year>2011</year>
<month>04</month>
<day>22</day>
<dayname>Friday</dayname>
</date>
</history>
</volume>
...
My c# code:
IEnumerable<XElement> caseIdLeavingVault =
from volume in root.Descendants("volume")
where
(from type in volume.Descendants("type")
where type.Value == "A"
select type).Any() &&
(from locationOld in volume.Descendants("location")
where
((String)locationOld.Attribute("type") == "old" &&
(String)locationOld.Element("repository") == "vault") &&
(from locationNew in volume.Descendants("location")
where
((String)locationNew.Attribute("type") == "new" &&
(String)locationNew.Element("repository") == "out")
select locationNew).Any()
select locationOld).Any()
select volume.Element("id");
...
foreach (XElement volume in caseIdLeavingVault)
{
Console.WriteLine(volume.Value.ToString());
}
谢谢。
好了，伙计们，我又被难住了。考虑到同样的情况和下面@Elian的解决方案(效果很好)，我需要
"optime"和"movedate"日期用于选择id的history。明白了吗?我希望以这样的结尾:
select new {
id = volume.Element("id").Value,
// this is from "optime"
opYear = <whaterver>("year").Value,
opMonth = <whatever>("month").Value,
opDay = <whatever>("day").Value,
// this is from "movedate"
mvYear = <whaterver>("year").Value,
mvMonth = <whatever>("month").Value,
mvDay = <whatever>("day").Value
}
我已经尝试了很多不同的组合，但是<date type="optime">和<date type="movedate">的Attribute s一直挡在我的路上，我似乎无法得到我想要的。
OK。我找到了一个很好的解决方案:
select new {
caseId = volume.Element("id").Value,
// this is from "optime"
opYear = volume.Descendants("date").Where(t => t.Attribute("type").Value == "optime").First().Element("year").Value,
opMonth = volume.Descendants("date").Where(t => t.Attribute("type").Value == "optime").First().Element("month").Value,
opDay = volume.Descendants("date").Where(t => t.Attribute("type").Value == "optime").First().Element("day").Value,
// this is from "movedate"
mvYear = volume.Descendants("date").Where(t => t.Attribute("type").Value == "movedate").First().Element("year").Value,
mvMonth = volume.Descendants("date").Where(t => t.Attribute("type").Value == "movedate").First().Element("month").Value,
mvDay = volume.Descendants("date").Where(t => t.Attribute("type").Value == "movedate").First().Element("day").Value
};
但是，当它发现id没有"movedate"时，它确实会失败。其中有一些是存在的，所以现在我正在研究它们。
嗯，昨天下午晚些时候，我终于想出了我一直想要的解决方案:
var caseIdLeavingSite =
from volume in root.Descendants("volume")
where volume.Elements("history").Any(
h => h.Element("type").Value == "A" &&
h.Elements("location").Any(l => l.Attribute("type").Value == "old" && ((l.Element("repository").Value == "site") ||
(l.Element("repository").Value == "init"))) &&
h.Elements("location").Any(l => l.Attribute("type").Value == "new" && l.Element("repository").Value == "toVault")
)
select new {
caseId = volume.Element("id").Value,
opYear = volume.Descendants("date").Where(t => t.Attribute("type").Value == "optime").First().Element("year").Value,
opMonth = volume.Descendants("date").Where(t => t.Attribute("type").Value == "optime").First().Element("month").Value,
opDay = volume.Descendants("date").Where(t => t.Attribute("type").Value == "optime").First().Element("day").Value,
mvYear = (volume.Descendants("date").Where(t => t.Attribute("type").Value == "movedate").Any() == true) ?
(volume.Descendants("date").Where(t => t.Attribute("type").Value == "movedate").First().Element("year").Value) : "0",
mvMonth = (volume.Descendants("date").Where(t => t.Attribute("type").Value == "movedate").Any() == true) ?
(volume.Descendants("date").Where(t => t.Attribute("type").Value == "movedate").First().Element("month").Value) : "0",
mvDay = (volume.Descendants("date").Where(t => t.Attribute("type").Value == "movedate").Any() == true) ?
(volume.Descendants("date").Where(t => t.Attribute("type").Value == "movedate").First().Element("day").Value) : "0"
};
这满足了@Elian帮助的需求，并获取了必要的额外日期信息。它还解释了使用三元操作符?:没有"movedate"元素的少数情况。
现在，如果有人知道如何使它更有效，我仍然感兴趣。谢谢。
我想你需要这样的东西:
IEnumerable<XElement> caseIdLeavingVault =
from volume in document.Descendants("volume")
where volume.Elements("history").Any(
h => h.Element("type").Value == "A" &&
h.Elements("location").Any(l => l.Attribute("type").Value == "old" && l.Element("repository").Value == "vault") &&
h.Elements("location").Any(l => l.Attribute("type").Value == "new" && l.Element("repository").Value == "out")
)
select volume.Element("id");
你的代码独立检查一个卷是否有类型为A的<history>元素和类型为<location>的<history>元素(不一定相同)。
上面的代码检查是否存在一个既属于A类型又包含所需的<location>元素的<history>元素。
Update: Abatishchev建议使用xpath查询而不是LINQ to XML的解决方案，但是他的查询太简单了，没有返回您所要求的内容。下面的xpath查询可以做到这一点，但它也有点长:
data/customer/mediatype/volume[history[type = 'A' and location[@type = 'old' and repository = 'vault'] and location[@type = 'new' and repository = 'out']]]/id
当您可以使用简单的XPath查询时，为什么要使用如此复杂和昂贵的LINQ到XML查询呢?
using System.Xml;
string xml = @"...";
string xpath = "data/customer/mediatype/volume/history/type[text()='A']/../location[@type='old' or @type='new']/../../id";
var doc = new XmlDocument();
doc.LoadXml(xml); // or use Load(path);
var nodes = doc.SelectNodes(xpath);
foreach (XmlNode node in nodes)
{
Console.WriteLine(node.InnerText); // 000049
}
或者如果您不需要XML DOM模型:
using System.Xml.XPath;
XPathDocument doc = null;
using (var stream = new StringReader(xml))
{
doc = new XPathDocument(stream); // specify just path to file if you have such one
}
var nav = doc.CreateNavigator();
XPathNodeIterator nodes = (XPathNodeIterator)nav.Evaluate(xpath);
foreach (XPathNavigator node in nodes)
{
Console.WriteLine(node.Value);
}