如何更改XML属性

Question

如何使用C#更改XML文件中元素的属性？

- Mike

---

http://www.developer.com/net/csharp/article.php/3489611 - IrishChieftain

简单来说：请发送代码。 - George Stocker

Answer 1

Mike; 每当我需要修改一个XML文档时，我都是这样做的：

//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

我希望你会发现这很有用。

- El Padrino

Answer 2

如果你正在使用3.5框架，可以使用LINQ to xml：

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");

- alexmac

---

非常好的一个，正是我所需要的。 如果您需要搜索特定的书籍属性，请在选择c之前附加.Where(c => (string)c.Attribute("myattribute") == "some value")。 - VisualBean

Answer 3

如果你想要更改的属性不存在或已被意外删除，则会引发异常。我建议你首先创建一个新的属性，然后将其传递到以下函数中：

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);
            }
        }
    }

用法：

   XmlAttribute attr = dom.CreateAttribute("name");
   attr.Value = value;
   SetAttrSafe(node, attr);

- Ahmad

Answer 4

以下是一个解析器类的开端，可以帮助你入门。这是我解决类似问题的方案：

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);
        }

    }
}

- E. A. Bagby