C# XML文档中的特定元素_C#_Xml_Linq

C# XML文档中的特定元素

c# xml linq

C# XML文档中的特定元素,c#,xml,linq,C#,Xml,Linq,我有以下XML： <?xml version="1.0" encoding="utf-8" ?> <catalog> <books> <book id="bk101"> <author id="1">Gambardella, Matthew</author> <title>XML Developer's Guide</title> <genre>Computer</

我有以下XML：

<?xml version="1.0" encoding="utf-8" ?>
<catalog>
  <books>
<book id="bk101"> 
  <author id="1">Gambardella, Matthew</author>
  <title>XML Developer's Guide</title>
  <genre>Computer</genre>
  <cover-price>
    <price>
        <country>US</country>
        <amount>44.95</amount>
    </price>
    <price>
        <country>UK</country>
        <amount>39.99</amount>
    </price>
  </cover-price>
  <unit-price>
    <price>
        <country>US</country>
        <amount>25.00</amount>
    </price>
    <price>
        <country>UK</country>
        <amount>20.00</amount>
    </price>
  </unit-price>
  <publish_date>2000-10-01</publish_date>
   <description> An in-depth look at creating applications with XML.</description>
</book>
<book id="bk102">
  <author id="2">Ralls, Kim</author>
  <title>Midnight Rain</title>
  <genre>Fantasy</genre>
  <cover-price>
    <price>
        <country>US</country>
        <amount>5.95</amount>
    </price>
    <price>
        <country>UK</country>
        <amount>3.99</amount>
    </price>
  </cover-price>
  <unit-price>
    <price>
        <country>US</country>
        <amount>2.50</amount>
    </price>
    <price>
        <country>UK</country>
        <amount>2.00</amount>
    </price>
  </unit-price>
  <publish_date>2000-12-16</publish_date>
  <description> A former architect battles corporate zombies,an evil sorceress, and her own childhood to become
queen of the world.</description>
</book>
<book id="bk103">
  <author id="3">Corets, Eva</author>
  <title>Maeve Ascendant</title>
  <genre>Fantasy</genre>
  <cover-price>
    <price>
        <country>US</country>
        <amount>5.95</amount>
    </price>
    <price>
        <country>UK</country>
        <amount>3.99</amount>
    </price>
  </cover-price>
  <unit-price>
    <price>
        <country>US</country>
        <amount>2.50</amount>
    </price>
    <price>
        <country>UK</country>
        <amount>2.00</amount>
    </price>
  </unit-price>
    <publish_date>2000-11-17</publish_date>
    <description>After the collapse of a nanotechnology society in England, the young survivors lay the foundation for
a new society. </description>
  </book>

<book id="bk104">
    <author id="4">Corets, Eva</author>
    <title>Oberon's Legacy</title>
    <genre>Fantasy</genre>
  <cover-price>
    <price>
        <country>US</country>
        <amount>5.95</amount>
    </price>
    <price>
        <country>UK</country>
        <amount>3.99</amount>
    </price>
  </cover-price>
  <unit-price>
    <price>
        <country>US</country>
        <amount>2.50</amount>
    </price>
    <price>
        <country>UK</country>
        <amount>2.00</amount>
    </price>
  </unit-price>
    <publish_date>2001-03-10</publish_date>
    <description>In post-apocalypse England, the mysterious agent known only as Oberon helps to create a new life for
 the inhabitants of London. Sequel to Maeve Ascendant.</description>

  </book>

<book id="bk105">
    <author id="5">Corets, Eva</author>
    <title>The Sundered Grail</title>
    <genre>Fantasy</genre>
  <cover-price>
    <price>
        <country>US</country>
        <amount>5.95</amount>
    </price>
    <price>
        <country>UK</country>
        <amount>3.99</amount>
    </price>
  </cover-price>
  <unit-price>
    <price>
        <country>US</country>
        <amount>2.50</amount>
    </price>
    <price>
        <country>UK</country>
        <amount>2.00</amount>
    </price>
  </unit-price>
    <publish_date>2001-09-10</publish_date>
    <description>The two daughters of Maeve, half-sisters, battle one another for control of England. Sequel to
Oberon's Legacy.</description>

  </book>
  </books>
</catalog>

那么，我如何为美国选择该书的封面价格金额？我尝试的每个组合只返回所有四个金额字段

目前，您正试图直接在
```
book
```
下获取
```
price
```
元素，因此这在一开始是行不通的
接下来，您只想选择带有右侧
```
country
```
子元素的
```
price
```
元素
最后，您不需要
```
price
```
元素的值，您需要它的
```
amount
```
子元素的值-我建议将其作为
```
十进制
```
而不是字符串

因此，这意味着：

Price = r.Element("price").Value

你想要的是：

Price = (decimal) r.Element("cover-price")
                   .Elements("price")
                   .Single(p => (string) p.Element("country") == "US")
                   .Element("amount")

如果没有任何

price

元素与正确的国家/地区匹配，则仍然会失败。您可以使用它来获取适当的

十进制数？

：

Price = (decimal?) r.Element("cover-price")
                    .Elements("price")
                    .SingleOrDefault(p => (string) p.Element("country") == "US")
                    ?.Element("amount")

目前，您正试图直接在
```
book
```
下获取
```
price
```
元素，因此这在一开始是行不通的
接下来，您只想选择带有右侧
```
country
```
子元素的
```
price
```
元素
最后，您不需要
```
price
```
元素的值，您需要它的
```
amount
```
子元素的值-我建议将其作为
```
十进制
```
而不是字符串

因此，这意味着：

Price = r.Element("price").Value

你想要的是：

Price = (decimal) r.Element("cover-price")
                   .Elements("price")
                   .Single(p => (string) p.Element("country") == "US")
                   .Element("amount")

如果没有任何

price

元素与正确的国家/地区匹配，则仍然会失败。您可以使用它来获取适当的

十进制数？

：

Price = (decimal?) r.Element("cover-price")
                    .Elements("price")
                    .SingleOrDefault(p => (string) p.Element("country") == "US")
                    ?.Element("amount")

你很接近

var selectedBook = from r in document.Descendants("book").Where
                                   (r=>(string)r.Attribute("id")=="bk102")
                        select new
                        {
                            Author = r.Element("author").Value,
                            Title = r.Element("title").Value,
                            Genere = r.Element("genre").Value,
                            Price = r.Element("price").Value,
                            PublishDate = r.Element("publish_date").Value,
                            Description = r.Element("description").Value,
                            USPrice = r.Element("cover-price") 
                                       .Descendants("country")
                                       .Where(c => (string)c == "US"))
                                       .Select(c => (decimal)c.Parent.Element("amount"))
                                       .First()
                        };

你很接近

var selectedBook = from r in document.Descendants("book").Where
                                   (r=>(string)r.Attribute("id")=="bk102")
                        select new
                        {
                            Author = r.Element("author").Value,
                            Title = r.Element("title").Value,
                            Genere = r.Element("genre").Value,
                            Price = r.Element("price").Value,
                            PublishDate = r.Element("publish_date").Value,
                            Description = r.Element("description").Value,
                            USPrice = r.Element("cover-price") 
                                       .Descendants("country")
                                       .Where(c => (string)c == "US"))
                                       .Select(c => (decimal)c.Parent.Element("amount"))
                                       .First()
                        };

您必须手动删除与您的首选项不匹配的价格，因为所有子项都将包含在内。请将您的XML缩减为一本或两本书-拥有所有这些数据没有任何好处。您必须手动删除与您的首选项不匹配的价格，因为所有的孩子都会被包括在内。请把你的XML压缩成一本或两本书——拥有这些数据没有任何好处。@JonSkeet是的，先生，我累了。谢谢你。@JonSkeet是的，先生，我累了。非常感谢。