使用 Linq to Xml 构建对象列表

发布于 2024-11-01 02:23:43 字数 1335 浏览 1 评论 0原文

我正在尝试使用 linq 从 XML 文件中提取值来创建对象列表。 XML 文件如下所示。

<RootNode>
  <Node1>
     <Node2>
        <results>
           <work>
              <title>title1</title>
              <author>author</author>
              <image_url>image</image_url>
            </work>
    ...
</RootNode>

XDocument results = XDocument.Load("url");

根据搜索，这些“工作”节点（以及后续子节点）可能会多次出现。对于每次出现的“作品”，我想提取标题/作者/图像值来构建一个简单的书籍对象：

public class Book
{
    public string Title { get; set; }
    public string Author { get; set; }
    public string ImageUrl { get; set; }
}

现在我可以迭代 xml 文件并使用类似这样的东西挑选出单独的值：

foreach (XElement element in results.Descendants("title"))
{
    string title = element.Value;
}

但是当我想构建一个我一直在尝试各种类似的书籍列表：

List<Book> books = 
    (from book in results.Descendants("work")
            select new Book
            {
                Title = book.Element("title").Value,
                Author = book.Element("name").Value,
                ImageUrl = book.Element("image_url").Value,
            }).ToList<Book>();

但是我不断收到空引用异常。任何指出我出错的地方的指示将不胜感激。

凯文.

编辑

大家好，问题出在 XML 文件上，而不是 linq 语句上。谢谢。

原文

I am trying to extract values from an XML file using linq to create a list of objects. The XML File looks like this.

<RootNode>
  <Node1>
     <Node2>
        <results>
           <work>
              <title>title1</title>
              <author>author</author>
              <image_url>image</image_url>
            </work>
    ...
</RootNode>

XDocument results = XDocument.Load("url");

There can be multiple occurrences of these 'work' nodes (and subsequent child nodes) depending on the search. For each occurrence of 'work' I want to extract the title/author/image values to build a simple book object:

public class Book
{
    public string Title { get; set; }
    public string Author { get; set; }
    public string ImageUrl { get; set; }
}

Now I can iterate through the xml file and pick out indivual values using something like this:

foreach (XElement element in results.Descendants("title"))
{
    string title = element.Value;
}

but as I want to build a list of books I have been trying various things much like this:

List<Book> books = 
    (from book in results.Descendants("work")
            select new Book
            {
                Title = book.Element("title").Value,
                Author = book.Element("name").Value,
                ImageUrl = book.Element("image_url").Value,
            }).ToList<Book>();

However I keep getting a null reference exceptionfor this. Any pointers of where I am going wrong would be greatly appreciated.

Kevin.

EDIT

Hi guys turns out the problem was with the XML file and not the linq statement. Thanks.

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想你的星星会说话 2024-11-08 02:23:43

经过几次小的修改后它对我有用：

    var books = (from book in results.Descendants("work")
        select new Book
                {
                    Title = book.Element("title").Value,
                    Author = book.Element("author").Value,
                    ImageUrl = book.Element("image").Value,
                }).ToList();

It works for me after several minor modifications:

    var books = (from book in results.Descendants("work")
        select new Book
                {
                    Title = book.Element("title").Value,
                    Author = book.Element("author").Value,
                    ImageUrl = book.Element("image").Value,
                }).ToList();

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