遍历XML的所有节点并解析存储在属性中的值

Question

I am trying to iterate over all nodes of an xml file and parse values stored in the attributes of "product-id" of nodes called "product".

My code looks like this.

using System;
using System.IO;
using System.Text;
using System.Xml;
using System.Xml.Linq;

class ReadFileFromFolder
{
    public static void Main()
    {
        XDocument xdoc = XDocument.Load("catalog.xml");

        foreach (XElement element in xdoc.Descendants())
        {
            if(element.Name == "product")
            {
                Console.WriteLine(element.Attributes["product-id"].Value);;   
            }
        }
    }
}

The error I get

projects/DotNetProjects/FilterProducts/FilterProducts/FilterProducts/ReadFileFromFolder.cs(35,35): Error CS0021: Cannot apply indexing with [] to an expression of type 'method group' (CS0021) (FilterProducts)

Super new to c# so probably something silly I am doing.

Answer 1

Using Linq-to-Xml it can be as simple as:

XDocument xdoc = XDocument.Load("catalog.xml");
var productids = xdoc.Descendants("product").Select(p => p.Attribute("product-id").Value);

Answer 2

'method group' means object's type has at least one method with that name. Group is used in the term because a method name can be overloaded. '[]' can only be used to index fields and properties.

ReadFileFromFolder.cs(35,35) means to go to line 35, column 35 for the best-effort location of the error. In many tools, double-clicking on the error message will take you there.

The place you are using '[]' is with the Attributes identifier. If you look at the documentation (F1) or declaration (F12), you'll see it is, in fact, a method group with one signature (not overloaded). So, call it with '()'.

Answer 3

Try accessing attributes with "(" . that is causing error. try below

class ReadFileFromFolder
    {
        public static void Main()
        {
            XDocument xdoc = XDocument.Load("catalog.xml");
            foreach (XElement element in xdoc.Descendants())
            {
                if(element.Name == "product"){
                    Console.WriteLine(element.Attributes("product-id").Value);;   
                }
            }
        }
    }