How can I change an attribute of an element in an XML file, using C#?
This question is related to
c#
xml
linq-to-xml
xmldocument
Mike; Everytime I need to modify an XML document I work it this way:
//Here is the variable with which you assign a new value to the attribute
string newValue = string.Empty;
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(xmlFile);
XmlNode node = xmlDoc.SelectSingleNode("Root/Node/Element");
node.Attributes[0].Value = newValue;
xmlDoc.Save(xmlFile);
//xmlFile is the path of your file to be modified
I hope you find it useful
Using LINQ to xml if you are using framework 3.5:
using System.Xml.Linq;
XDocument xmlFile = XDocument.Load("books.xml");
var query = from c in xmlFile.Elements("catalog").Elements("book")
select c;
foreach (XElement book in query)
{
book.Attribute("attr1").Value = "MyNewValue";
}
xmlFile.Save("books.xml");
Mike; Everytime I need to modify an XML document I work it this way:
//Here is the variable with which you assign a new value to the attribute
string newValue = string.Empty;
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(xmlFile);
XmlNode node = xmlDoc.SelectSingleNode("Root/Node/Element");
node.Attributes[0].Value = newValue;
xmlDoc.Save(xmlFile);
//xmlFile is the path of your file to be modified
I hope you find it useful
Here's the beginnings of a parser class to get you started. This ended up being my solution to a similar problem:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Linq;
namespace XML
{
public class Parser
{
private string _FilePath = string.Empty;
private XDocument _XML_Doc = null;
public Parser(string filePath)
{
_FilePath = filePath;
_XML_Doc = XDocument.Load(_FilePath);
}
/// <summary>
/// Replaces values of all attributes of a given name (attributeName) with the specified new value (newValue) in all elements.
/// </summary>
/// <param name="attributeName"></param>
/// <param name="newValue"></param>
public void ReplaceAtrribute(string attributeName, string newValue)
{
ReplaceAtrribute(string.Empty, attributeName, new List<string> { }, newValue);
}
/// <summary>
/// Replaces values of all attributes of a given name (attributeName) with the specified new value (newValue) in elements with a given name (elementName).
/// </summary>
/// <param name="elementName"></param>
/// <param name="attributeName"></param>
/// <param name="newValue"></param>
public void ReplaceAtrribute(string elementName, string attributeName, string newValue)
{
ReplaceAtrribute(elementName, attributeName, new List<string> { }, newValue);
}
/// <summary>
/// Replaces values of all attributes of a given name (attributeName) and value (oldValue)
/// with the specified new value (newValue) in elements with a given name (elementName).
/// </summary>
/// <param name="elementName"></param>
/// <param name="attributeName"></param>
/// <param name="oldValue"></param>
/// <param name="newValue"></param>
public void ReplaceAtrribute(string elementName, string attributeName, string oldValue, string newValue)
{
ReplaceAtrribute(elementName, attributeName, new List<string> { oldValue }, newValue);
}
/// <summary>
/// Replaces values of all attributes of a given name (attributeName), which has one of a list of values (oldValues),
/// with the specified new value (newValue) in elements with a given name (elementName).
/// If oldValues is empty then oldValues will be ignored.
/// </summary>
/// <param name="elementName"></param>
/// <param name="attributeName"></param>
/// <param name="oldValues"></param>
/// <param name="newValue"></param>
public void ReplaceAtrribute(string elementName, string attributeName, List<string> oldValues, string newValue)
{
List<XElement> elements = _XML_Doc.Elements().Descendants().ToList();
foreach (XElement element in elements)
{
if (elementName == string.Empty | element.Name.LocalName.ToString() == elementName)
{
if (element.Attribute(attributeName) != null)
{
if (oldValues.Count == 0 || oldValues.Contains(element.Attribute(attributeName).Value))
{ element.Attribute(attributeName).Value = newValue; }
}
}
}
}
public void SaveChangesToFile()
{
_XML_Doc.Save(_FilePath);
}
}
}
Using LINQ to xml if you are using framework 3.5:
using System.Xml.Linq;
XDocument xmlFile = XDocument.Load("books.xml");
var query = from c in xmlFile.Elements("catalog").Elements("book")
select c;
foreach (XElement book in query)
{
book.Attribute("attr1").Value = "MyNewValue";
}
xmlFile.Save("books.xml");
Mike; Everytime I need to modify an XML document I work it this way:
//Here is the variable with which you assign a new value to the attribute
string newValue = string.Empty;
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(xmlFile);
XmlNode node = xmlDoc.SelectSingleNode("Root/Node/Element");
node.Attributes[0].Value = newValue;
xmlDoc.Save(xmlFile);
//xmlFile is the path of your file to be modified
I hope you find it useful
Here's the beginnings of a parser class to get you started. This ended up being my solution to a similar problem:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Xml.Linq;
namespace XML
{
public class Parser
{
private string _FilePath = string.Empty;
private XDocument _XML_Doc = null;
public Parser(string filePath)
{
_FilePath = filePath;
_XML_Doc = XDocument.Load(_FilePath);
}
/// <summary>
/// Replaces values of all attributes of a given name (attributeName) with the specified new value (newValue) in all elements.
/// </summary>
/// <param name="attributeName"></param>
/// <param name="newValue"></param>
public void ReplaceAtrribute(string attributeName, string newValue)
{
ReplaceAtrribute(string.Empty, attributeName, new List<string> { }, newValue);
}
/// <summary>
/// Replaces values of all attributes of a given name (attributeName) with the specified new value (newValue) in elements with a given name (elementName).
/// </summary>
/// <param name="elementName"></param>
/// <param name="attributeName"></param>
/// <param name="newValue"></param>
public void ReplaceAtrribute(string elementName, string attributeName, string newValue)
{
ReplaceAtrribute(elementName, attributeName, new List<string> { }, newValue);
}
/// <summary>
/// Replaces values of all attributes of a given name (attributeName) and value (oldValue)
/// with the specified new value (newValue) in elements with a given name (elementName).
/// </summary>
/// <param name="elementName"></param>
/// <param name="attributeName"></param>
/// <param name="oldValue"></param>
/// <param name="newValue"></param>
public void ReplaceAtrribute(string elementName, string attributeName, string oldValue, string newValue)
{
ReplaceAtrribute(elementName, attributeName, new List<string> { oldValue }, newValue);
}
/// <summary>
/// Replaces values of all attributes of a given name (attributeName), which has one of a list of values (oldValues),
/// with the specified new value (newValue) in elements with a given name (elementName).
/// If oldValues is empty then oldValues will be ignored.
/// </summary>
/// <param name="elementName"></param>
/// <param name="attributeName"></param>
/// <param name="oldValues"></param>
/// <param name="newValue"></param>
public void ReplaceAtrribute(string elementName, string attributeName, List<string> oldValues, string newValue)
{
List<XElement> elements = _XML_Doc.Elements().Descendants().ToList();
foreach (XElement element in elements)
{
if (elementName == string.Empty | element.Name.LocalName.ToString() == elementName)
{
if (element.Attribute(attributeName) != null)
{
if (oldValues.Count == 0 || oldValues.Contains(element.Attribute(attributeName).Value))
{ element.Attribute(attributeName).Value = newValue; }
}
}
}
}
public void SaveChangesToFile()
{
_XML_Doc.Save(_FilePath);
}
}
}
Using LINQ to xml if you are using framework 3.5:
using System.Xml.Linq;
XDocument xmlFile = XDocument.Load("books.xml");
var query = from c in xmlFile.Elements("catalog").Elements("book")
select c;
foreach (XElement book in query)
{
book.Attribute("attr1").Value = "MyNewValue";
}
xmlFile.Save("books.xml");
Mike; Everytime I need to modify an XML document I work it this way:
//Here is the variable with which you assign a new value to the attribute
string newValue = string.Empty;
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.Load(xmlFile);
XmlNode node = xmlDoc.SelectSingleNode("Root/Node/Element");
node.Attributes[0].Value = newValue;
xmlDoc.Save(xmlFile);
//xmlFile is the path of your file to be modified
I hope you find it useful
If the attribute you want to change doesn't exist or has been accidentally removed, then an exception occurs. I suggest you first create a new attribute and send it to a function like the following:
private void SetAttrSafe(XmlNode node,params XmlAttribute[] attrList)
{
foreach (var attr in attrList)
{
if (node.Attributes[attr.Name] != null)
{
node.Attributes[attr.Name].Value = attr.Value;
}
else
{
node.Attributes.Append(attr);
}
}
}
Usage:
XmlAttribute attr = dom.CreateAttribute("name");
attr.Value = value;
SetAttrSafe(node, attr);
Source: Stackoverflow.com