Linq to XML - 搜索深层元素是否存在

发布于 2024-11-04 07:25:50 字数 820 浏览 1 评论 0原文

我只想检查 XML 文件中是否存在某个元素。该元素有几层深。下面的代码工作正常，但这是我能想到的最短的语法。谁能想出一种方法来更流畅地完成此操作，而无需诉诸经典的 XPath 语法？

        //create simple sample xml
        XDocument doc = new XDocument(
        new XDeclaration("1.0", "utf-8", "yes"),
        new XElement("Bookstore",
            new XAttribute("Name", "MyBookstore"),
            new XElement("Books",
                new XElement("Book",
                    new XAttribute("Title", "MyBook"),
                    new XAttribute("ISBN", "1234")))));

        //write out a boolean indicating if the book exists
        Console.WriteLine(
            doc.Element("Bookstore") != null &&
            doc.Element("Bookstore").Element("Books") != null &&
            doc.Element("Bookstore").Element("Books").Element("Book") != null
        );

原文

I simply want to check to see if a certain element exists in my XML file. The element is a few levels deep. The following code works fine, but is the shortest syntax I can come up with. Can anyone think of a way to do this more fluently without resorting to classic XPath syntax?

        //create simple sample xml
        XDocument doc = new XDocument(
        new XDeclaration("1.0", "utf-8", "yes"),
        new XElement("Bookstore",
            new XAttribute("Name", "MyBookstore"),
            new XElement("Books",
                new XElement("Book",
                    new XAttribute("Title", "MyBook"),
                    new XAttribute("ISBN", "1234")))));

        //write out a boolean indicating if the book exists
        Console.WriteLine(
            doc.Element("Bookstore") != null &&
            doc.Element("Bookstore").Element("Books") != null &&
            doc.Element("Bookstore").Element("Books").Element("Book") != null
        );

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后知后觉 2024-11-11 07:25:50

Console.WriteLine(doc.Root.Descendants("Book").Any());

Console.WriteLine(doc.Root.Descendants("Book").Any());

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上课铃就是安魂曲 2024-11-11 07:25:50

这可行 - 假设您确实需要确切的层次结构，因为它们可能是不相关子树中的 Book 节点，否则您可以使用 Descendants() ：

Console.WriteLine( doc.Elements("Bookstore")
                      .Elements("Books")
                      .Elements("Book")
                      .Any());

复数 < code>Elements() 不需要 null 检查，因为如果不存在这样的元素，它只会返回一个空枚举，因此它仍然是可链接的。

This would work - assuming you actually do need the exact hierarchy because they might be a Book node in an unrelated sub tree, otherwise you can use Descendants():

Console.WriteLine( doc.Elements("Bookstore")
                      .Elements("Books")
                      .Elements("Book")
                      .Any());

The plural Elements() does not require the null check since it will just return an empty enumeration if no such element exists, so it is still chainable.

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溇涏 2024-11-11 07:25:50

可能不会更短，但是：

var isBookExist = 
    (from store in doc.Elements("Bookstore")
     from books in store.Elements("Books")
     from book in books.Elements("Book")
     select book).Any();

Probably not shorter but:

var isBookExist = 
    (from store in doc.Elements("Bookstore")
     from books in store.Elements("Books")
     from book in books.Elements("Book")
     select book).Any();

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~没有更多了~