问题

我有一个XML文件块在这里。我想要提取所有ToyId的实例并将其放入一个数组中。同时只提取具有"Hastoys = "YES""属性的节点。

<Bookstore Hastoys="YES"> 
  <Authors>7</Authors>
  <Location>Austin TX</Location>
  <Employees>15</Employees>
  <ToyList>
    <ToyId>124</ToyId>
    <ToyId>1251</ToyId>
  </ToyList>
  <ToyList>
    <ToyId>255-2</ToyId>
    <ToyId>6623</ToyID>
  </ToyList>
</Bookstore>

var list =  from r in doc.Descendants("Bookstore")
            .Where(node => (string)node.Attribute("HasToys") == "YES")
            select new
            {
                ToyId = r.Element("ToyList")?.Element("ToyId")?.Value,
            };

我尝试使用上面的查询，但它只返回我ToyId的第一个实例，然后转到下一个块。所以输出将是：124，然后跳过其他ToyId。

<Bookstore Hastoys="YES"> 
  <Authors>7</Authors>
  <Location>Austin TX</Location>
  <Employees>15</Employees>
  <ToyList>
    <ToyId>124</ToyId>
    <ToyId>1251</ToyId>
  </ToyList>
  <ToyList>
    <ToyId>255-2</ToyId>
    <ToyId>6623</ToyID>
  </ToyList>
</Bookstore>

var list =  from r in doc.Descendants("Bookstore")
            .Where(node => (string)node.Attribute("HasToys") == "YES")
            select new
            {
                ToyId = r.Element("ToyList")?.Element("ToyId")?.Value,
            };

答案1

得分: 2

从您的XML中存在一些问题/顾虑：

1. `<ToyId>` 元素的无效闭合标签为

```xml
&lt;ToyId&gt;6623&lt;/ToyID&gt;

2. 在 Bookstore 元素中的属性为 "Hastoys"

<Bookstore Hastoys="YES"> 

但是您的代码中引用的是 "HasToys"

(string)node.Attribute("HasToys") == "YES"

方法 1

假设您修复了上述提到的问题，使用 .Descendants("ToyList").Elements("ToyId") 获取 ToyList 元素下的每个 ToyId 元素。

string xml = @"<Bookstore HasToys=&quot;&quot;YES&quot;&quot;&gt; 
    &lt;Authors&gt;7&lt;/Authors&gt;
    &lt;Location&gt;Austin TX&lt;/Location&gt;
    &lt;Employees&gt;15&lt;/Employees&gt;
    &lt;ToyList&gt;
        &lt;ToyId&gt;124&lt;/ToyId&gt;
        &lt;ToyId&gt;1251&lt;/ToyId&gt;
    &lt;/ToyList&gt;
    &lt;ToyList&gt;
        &lt;ToyId&gt;255-2&lt;/ToyId&gt;
        &lt;ToyId&gt;6623&lt;/ToyId&gt;
    &lt;/ToyList&gt;
&lt;/Bookstore&gt;";

XDocument doc = XDocument.Parse(xml);

var list = (from r in doc.Descendants("Bookstore")
              .Where(node => (string)node.Attribute("HasToys") == "YES")
                .Descendants("ToyList")
                .Elements("ToyId")
              select new
              {
                    ToyId = r.Value,
              });

方法 2

您也可以使用 XPath

XmlDocument doc = new XmlDocument();
doc.LoadXml(xml);

XmlNode root = doc.DocumentElement;
var list = root.SelectNodes("//Bookstore[@HasToys='YES']/ToyList/ToyId").Cast<XmlNode>()    
    .Select(x => new
              {
                    ToyId = x.InnerText
              })
    .ToList();

<details>
<summary>英文:</summary>

Few issues/concerns from your XML:

1. Invalid closing tag for

<ToyId>6623</ToyID>

2. The attribute in `Bookstore` element is "Hastoys"

<Bookstore Hastoys="YES">

But your code is referring "HasToys"

(string)node.Attribute("HasToys") == "YES"

**Approach 1**

Assume that you fixed the mentioned issues/concerns, working with `.Descendants("ToyList").Elements("ToyId")` to get each `ToyId` element under the `ToyList` elements.

```csharp
string xml = @"<Bookstore HasToys=""YES""> 
    <Authors>7</Authors>
    <Location>Austin TX</Location>
    <Employees>15</Employees>
    <ToyList>
        <ToyId>124</ToyId>
        <ToyId>1251</ToyId>
    </ToyList>
    <ToyList>
        <ToyId>255-2</ToyId>
        <ToyId>6623</ToyId>
    </ToyList>
</Bookstore>";

XDocument doc = XDocument.Parse(xml);

var list = (from r in doc.Descendants("Bookstore")
              .Where(node => (string)node.Attribute("HasToys") == "YES")
                .Descendants("ToyList")
                .Elements("ToyId")
              select new
              {
                    ToyId = r.Value,
              });

Approach 2

You may work with XPath as well

XmlDocument doc = new XmlDocument();
doc.LoadXml(xml);

XmlNode root = doc.DocumentElement;
var list = root.SelectNodes("//Bookstore[@HasToys='YES']/ToyList/ToyId").Cast<XmlNode>()    
    .Select(x => new
              {
                    ToyId = x.InnerText
              })
    .ToList();