c# - 如何使用 C# 和 LINQ 深入提取 XML 中的信息？

Question

这是我在 StackOverflow 上的第一篇文章，所以请多多包涵。如果我的代码示例有点长，我先表示歉意。

使用 C# 和 LINQ，我试图识别一系列第三级 id元素(在本例中为 000049)在一个更大的 XML 文件中。每三级id是独一无二的，我想要的是基于每个人的一系列后代信息。更具体地说，如果 type == A和 location type(old) == vault和 location type(new) == out , 然后我想选择 id .下面是我正在使用的 XML 和 C# 代码。

总的来说，我的代码有效。如下所示，它将返回 id 000049 两次，这是正确的。但是，我发现了一个小故障。如果我删除第一个 history包含 type == A 的 block ，我的代码仍然返回 id 000049 两次，而它应该只返回一次。我知道为什么会这样，但我想不出更好的方法来运行查询。有没有更好的方法来运行我的查询以获得我想要的输出并仍然使用 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>
            ...

我的 C# 代码:

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。

---

好吧，我又被难住了。鉴于同样的情况和下面@Elian 的解决方案(效果很好)，我需要 "optime"和 "movedate" history 的日期用于选择 id .那有意义吗？我希望以这样的方式结束:

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 
} 

我尝试了很多不同的组合，但是 Attribute s <date type="optime">和 <date type="movedate">一直挡着我的路，我似乎得不到我想要的。

---

好的。我找到了一个 solution效果很好:

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，当它找到 id 时它确实失败了没有 "movedate" .其中一些存在，所以现在我正在努力。

---

好吧，昨天下午晚些时候我终于找到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 帮助的要求并获取了必要的额外日期信息。当没有 "movedate" 的元素时，它也说明了那些少数情况。通过使用三元运算符 ?: .

现在，如果有人知道如何提高效率，我仍然很感兴趣。谢谢。

Answer 1

我想你想要这样的东西:

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");

您的代码独立检查卷是否有 <history>元素类型 A和一个(不一定相同)<history>具有所需 <location> 的元素元素。

上面的代码检查是否存在 <history>类型均为 A 的元素并包含所需的 <location>元素。

更新:Abatishchev 建议使用 xpath 查询而不是 LINQ to XML 的解决方案，但他的查询过于简单，无法准确返回您要求的内容。以下 xpath 查询可以解决问题，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