如何在XML文件中检索满足特定条件的数据？

Question

I have an XML file, and I want to retrieve the brandname when brandcode is 001 from the following XML.

    <Root>
-   <data>
  <Companycode>TF</Companycode> 
  <Productcode>00001</Productcode> 
  <Productname>VPU</Productname> 
  <Brandcode>001</Brandcode> 
  <Brandname>DB</Brandname> 
  </data>
- <data>
  <Companycode>TF</Companycode> 
  <Productcode>00002</Productcode> 
  <Productname>SENDERCARD</Productname> 
  <Brandcode>002</Brandcode> 
  <Brandname>LINSN</Brandname> 
  </data>
</Root>

This is my code; I need to assign Brand Name here:

XmlTextReader textReader = new XmlTextReader(@"codedata.xml");
            textReader.Read();

            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(textReader);

            XmlNodeList BCode = xmlDoc.GetElementsByTagName("Brandcode");
            XmlNodeList BName = xmlDoc.GetElementsByTagName("Brandname");
            for (int i = 0; i < BCode.Count; i++)
            {
                if (BCode[i].InnerText =="001")
                {
                    string brandname = BName[i].InnerText;
                }
                    //Console.WriteLine(BName[i].InnerText);
            }

Answer 1

Try In this way...

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Xml;

namespace XmlReading
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create an instance of the XmlTextReader and call Read method to read the file            
            XmlTextReader textReader = new XmlTextReader("D:\\myxml.xml");
            textReader.Read();

            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(textReader);

            XmlNodeList BCode = xmlDoc.GetElementsByTagName("Brandcode");
            XmlNodeList BName = xmlDoc.GetElementsByTagName("Brandname");
            for (int i = 0; i < BCode.Count; i++)
            {
                if (BCode[i].InnerText == "001")
                    Console.WriteLine(BName[i].InnerText);                
            }

            Console.ReadLine();
        }
    }
}

Answer 2

Try this XPath : //Brandname[../Brandcode[text()='001']]

Using XmlDocument.SelectSingleNode :

var document = new XmlDocument();
var Brandcode = "001";
var xpath = String.Format(@"//Brandname[../Brandcode[text()='{0}']]", 
                          Brandcode);
var Brandname = document.SelectSingleNode(xpath).InnerText;

and using XDocument.XPathSelectElement :

var document = XDocument.Load("fileName");
var name = document.XPathSelectElement(xpath).Value;

Answer 3

YOu can use Xml.Linq namespace, with XDocument class to load and select the exact element from the xml file:

XDocument doc = XDocument.Load(@"filePath");
var query = doc.Descendants("Root").Where(w => w.Element("Brandcode").Value == "001").Select(s => new { s.Element("Brandname").Value }).FirstOrDefault();
string brandname = query.Value;

Answer 4

Define the brandname as string and assign null to it and then use the brand name where ever you want....

namespace XmlReading
{
    class Program
    {
        static void Main(string[] args)
        {
            //Create an instance of the XmlTextReader and call Read method to read the file            
            XmlTextReader textReader = new XmlTextReader("D:\\myxml.xml");
            textReader.Read();

            string brandname = null;

            XmlDocument xmlDoc = new XmlDocument();
            xmlDoc.Load(textReader);

            XmlNodeList BCode = xmlDoc.GetElementsByTagName("Brandcode");
            XmlNodeList BName = xmlDoc.GetElementsByTagName("Brandname");
            for (int i = 0; i < BCode.Count; i++)
            {
                if (BCode[i].InnerText == "001")
                {
                    brandname = BName[i].InnerText;                    
                }
            }
            Console.WriteLine(brandname);
            Console.ReadLine();
        }
    }
}