[英]Linq to XML - update/alter the nodes of an XML Document
我有兩個問題:
1.我已經開始使用Linq來處理XML,我想知道是否可以通過Linq更改XML文檔。 我的意思是,有什么喜歡的
XDocument xmlDoc = XDocument.Load("sample.xml");
update item in xmlDoc.Descendants("item")
where (int)item .Attribute("id") == id
...
2.我已經知道如何通過簡單地使用創建和添加新的XMLElement
xmlDoc.Element("items").Add(new XElement(......);
但是如何刪除單個條目?
XML樣本數據:
<items>
<item id="1" name="sample1" info="sample1 info" web="" />
<item id="2" name="sample2" info="sample2 info" web="" />
</itmes>
謝謝您的回答。 一切正常。
就像我的問題的完整性一樣,下面的代碼顯示了如何修改單個條目:
string xml = @"<data><record id='1' info='sample Info'/><record id='2' info='sample Info'/><record id='3' info='sample Info'/></data>";
StringReader sr = new StringReader(xml);
XDocument d = XDocument.Load(sr);
d.Descendants("record").Where(x => x.Attribute("id").Value == "2").Single().SetAttributeValue("info", "new sample info");
這是你的想法嗎?
using System;
using System.Linq;
using System.Xml.Linq;
static void Main(string[] args)
{
string xml = @"<data><record id='1'/><record id='2'/><record id='3'/></data>";
StringReader sr = new StringReader(xml);
XDocument d = XDocument.Load(sr);
// the verbose way, if you will be removing many elements (though in
// this case, we're only removing one)
var list = from XElement e in d.Descendants("record")
where e.Attribute("id").Value == "2"
select e;
// convert the list to an array so that we're not modifying the
// collection that we're iterating over
foreach (XElement e in list.ToArray())
{
e.Remove();
}
// the concise way, which only works if you're removing a single element
// (and will blow up if the element isn't found)
d.Descendants("record").Where(x => x.Attribute("id").Value == "3").Single().Remove();
XmlWriter xw = XmlWriter.Create(Console.Out);
d.WriteTo(xw);
xw.Flush();
Console.ReadLine();
}
答案在這個帖子中...你只需要做很多排序就可以找到它們,所以我已經完成了為你拼湊它們的工作:
現在,如果您正在閱讀此主題,您可能想知道如何編輯元素。 數據存儲在xml中有兩種不同的方式,例如:
<tagName attributeName="some value">another value</tagName>
為了編輯屬性的值,knox回答了他自己的問題:
d.Descendants("record").Where(x => x.Attribute("id").Value == "2").Single().SetAttributeValue("info", "new sample info");
換句話說,獲取要更改的XElement,並調用element.SetAttributeValue(“AttributeName”,“屬性的新值”)
如果你想編輯標簽的值或內容 ,那么Ajay會回答它(如果你仔細檢查他的所有代碼):
persondata.Element("City").Value = txtCity.Text;
或者,換句話說,一旦你擁有了你所追求的XElement,只需使用.Value並分配。
請記住,在對內存中的元素執行任何這些修改之后,如果要將這些更改保留到磁盤,則必須在XDocument上調用.Save()。
使用系統; 使用System.Collections.Generic; 使用System.Linq; 使用System.Text; 使用System.Xml.Linq; //使用System.Xml;
namespace XMLtoLinqApp {class Program {static void Main(string [] args){
//XmlDocument doc = new XmlDocument();
//XmlElement newBook=doc.CreateElement("BookParticipant");
//newBook.SetAttribute("Author");
//Using Functional Construction to Create an XML Schema
XElement xBookParticipant = new XElement("BookParticipant",
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz"));
Console.WriteLine(xBookParticipant.ToString());
//Creates the Same XML Tree as Listing 6-1 but with Far Less Code
XElement xBookParticipants = new XElement("BookParticipants",
new XElement("BookParticipant",
new XAttribute("type", "Author"),
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz")),
new XElement("BookParticipant",
new XAttribute("type", "Editor"),
new XElement("FirstName", "Ewan"),
new XElement("LastName", "Buckingham")));
Console.WriteLine(xBookParticipants.ToString());
//-- Disadvatages of XML document
//System.Xml.XmlElement xmlBookParticipant = new System.Xml.XmlElement("BookParticipant");
XElement xeBookParticipant = new XElement("BookParticipant");
XDocument xDocument = new XDocument(new XElement("BookParticipants",
new XElement("BookParticipant",
new XAttribute("type", "Author"),
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz"))));
Console.WriteLine(xDocument.ToString());
//--Calling the ToString Method on an Element Produces the XML Tree
XElement name = new XElement("Name", "Joe");
Console.WriteLine(name.ToString());
//--Console.WriteLine Implicitly Calling the ToString Method on an Element to Produce an XML Tree
XElement name1 = new XElement("Person",
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz"));
Console.WriteLine(name1);
//-- Casting an Element to Its Value’s Data Type Outputs the Value
Console.WriteLine(name);
Console.WriteLine((string)name);
//--Different Node Value Types Retrieved via Casting to the Node Value’s Type
XElement count = new XElement("Count", 12);
Console.WriteLine(count);
Console.WriteLine((int)count);
XElement smoker = new XElement("Smoker", false);
Console.WriteLine(smoker);
Console.WriteLine((bool)smoker);
XElement pi = new XElement("Pi", 3.1415926535);
Console.WriteLine(pi);
Console.WriteLine((double)pi);
DeferredQryProblem();
GenerateXMlFromLinqQry();
WithoutReaching();
Ancestors();
AncestorsAndSelf();
SortSample();
FindElementwithSpecificChild();
}
private static void DeferredQryProblem()
{
XDocument xDocument = new XDocument(
new XElement("BookParticipants",
new XElement("BookParticipant",
new XAttribute("type", "Author"),
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz")),
new XElement("BookParticipant",
new XAttribute("type", "Editor"),
new XElement("FirstName", "Ewan"),
new XElement("LastName", "Buckingham"))));
IEnumerable<XElement> elements =
xDocument.Element("BookParticipants").Elements("BookParticipant");
foreach (XElement element in elements)
{
Console.WriteLine("Source element: {0} : value = {1}",
element.Name, element.Value);
}
foreach (XElement element in elements)
{
Console.WriteLine("Removing {0} = {1} ...", element.Name, element.Value);
element.Remove();
}
Console.WriteLine(xDocument);
foreach (XElement element in elements)
{
Console.WriteLine("Source element: {0} : value = {1}",
element.Name, element.Value);
}
foreach (XElement element in elements.ToArray())
{
Console.WriteLine("Removing {0} = {1} ...", element.Name, element.Value);
element.Remove();
}
Console.WriteLine(xDocument);
}
//-- Creating an Attribute and Adding It to Its Element
private static void CreatingAttribute()
{
XElement xBookParticipant = new XElement("BookParticipant", new XAttribute("type", "Author"));
Console.WriteLine(xBookParticipant);
}
//--Creating a Comment with Functional Construction
private static void CreatingComment()
{
XElement xBookParticipant = new XElement("BookParticipant",
new XComment("This person is retired."));
Console.WriteLine(xBookParticipant);
}
//--Creating a Declaration with Functional Construction
private static void CreateXmlDeclaration()
{
XDocument xDocument = new XDocument(new XDeclaration("1.0", "UTF-8", "yes"),
新的XElement(“BookParticipant”)); Console.WriteLine(的XDocument); }
private static void GenerateXMlFromLinqQry()
{
BookParticipant[] bookParticipants = new[] {new BookParticipant {FirstName = "Joe", LastName = "Rattz",
ParticipantType = ParticipantTypes.Author},
new BookParticipant {FirstName = "Ewan", LastName = "Buckingham",
ParticipantType = ParticipantTypes.Editor}
};
XElement xBookParticipants =
new XElement("BookParticipants",
bookParticipants.Select(p =>
new XElement("BookParticipant",
new XAttribute("type", p.ParticipantType),
new XElement("FirstName", p.FirstName),
new XElement("LastName", p.LastName))));
Console.WriteLine(xBookParticipants);
}
//-- Obtaining Elements Without Reaching
private static void WithoutReaching()
{
XDocument xDocument = new XDocument(new XElement("BookParticipants",
new XElement("BookParticipant",
new XAttribute("type", "Author"),
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz")),
new XElement("BookParticipant",
new XAttribute("type", "Editor"),
new XElement("FirstName", "Ewan"),
new XElement("LastName", "Buckingham"))));
//-- Simple Descendants
IEnumerable<XElement> elements = xDocument.Descendants("BookParticipant");
foreach (XElement element in elements)
{
Console.WriteLine("Element: {0} : value = {1}",
element.Name, element.Value);
}
//-- Descendants with Where Clause
IEnumerable<XElement> elements1 = xDocument.Descendants("BookParticipant")
.Where(e => ((string)e.Element("FirstName")) == "Ewan");
foreach (XElement element1 in elements1)
{
Console.WriteLine("Element: {0} : value = {1}",
element1.Name, element1.Value);
}
}
//-- Ancestors Prototype
private static void Ancestors()
{
XDocument xDocument = new XDocument(new XElement("BookParticipants",
new XElement("BookParticipant",
new XAttribute("type", "Author"),
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz")),
new XElement("BookParticipant",
new XAttribute("type", "Editor"),
new XElement("FirstName", "Ewan"),
new XElement("LastName", "Buckingham"))));
IEnumerable<XElement> elements = xDocument.Element("BookParticipants").Descendants("FirstName");
// First, I will display the source elements.
foreach (XElement element in elements)
{
Console.WriteLine("Source element: {0} : value = {1}",
element.Name, element.Value);
}
// Now, I will display the ancestor elements for each source element.
foreach (XElement element in elements.Ancestors())
{
Console.WriteLine("Ancestor element: {0}", element.Name);
}
// Now, I will display the ancestor elements for each source element.
foreach (XElement element in elements.Ancestors("BookParticipant"))
{
Console.WriteLine("Ancestor element: {0}", element.Name);
}
}
//-- AncestorsAndSelf
private static void AncestorsAndSelf()
{
XDocument xDocument = new XDocument(
new XElement("BookParticipants",
new XElement("BookParticipant",
new XAttribute("type", "Author"),
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz")),
new XElement("BookParticipant",
new XAttribute("type", "Editor"),
new XElement("FirstName", "Ewan"),
new XElement("LastName", "Buckingham"))));
IEnumerable<XElement> elements =
xDocument.Element("BookParticipants").Descendants("FirstName");
// First, I will display the source elements.
foreach (XElement element in elements)
{
Console.WriteLine("Source element: {0} : value = {1}",
element.Name, element.Value);
}
// Now, I will display the ancestor elements for each source element.
foreach (XElement element in elements.AncestorsAndSelf())
{
Console.WriteLine("Ancestor element: {0}", element.Name);
}
// Now, I will display the ancestor elements for each source element.
foreach (XElement element in elements.AncestorsAndSelf("BookParticipant"))
{
Console.WriteLine("Ancestor element: {0}", element.Name);
}
}
//-- Sort Smaple
private static void SortSample()
{
XElement root = XElement.Load("Data.xml");
IEnumerable<decimal> prices =
from el in root.Elements("Data")
let price = (decimal)el.Element("Price")
orderby price
select price;
foreach (decimal el in prices)
Console.WriteLine(el);
}
//-- Find an Element with a Specific Child
private static void FindElementwithSpecificChild()
{
XElement root = XElement.Load("data.xml");
IEnumerable<XElement> tests =
from el in root.Elements("Data")
where (int)el.Element("Quantity") > 3
select el;
foreach (XElement el in tests)
Console.WriteLine((string)el.Attribute("TestId");
}
}
}
http://msdn.microsoft.com/en-us/library/bb387053.aspx
7.25 - > A 3 24.50 B 1 89.99 A 5 4.95 A 3 66.00 B 10 .99 A 15 29.00 B 8 6.99
static void Main(string[] args)
{
//XmlDocument doc = new XmlDocument();
//XmlElement newBook=doc.CreateElement("BookParticipant");
//newBook.SetAttribute("Author");
//Using Functional Construction to Create an XML Schema
XElement xBookParticipant = new XElement("BookParticipant",
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz"));
Console.WriteLine(xBookParticipant.ToString());
//Creates the Same XML Tree as Listing 6-1 but with Far Less Code
XElement xBookParticipants = new XElement("BookParticipants",
new XElement("BookParticipant",
new XAttribute("type", "Author"),
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz")),
new XElement("BookParticipant",
new XAttribute("type", "Editor"),
new XElement("FirstName", "Ewan"),
new XElement("LastName", "Buckingham")));
Console.WriteLine(xBookParticipants.ToString());
//-- Disadvatages of XML document
//System.Xml.XmlElement xmlBookParticipant = new System.Xml.XmlElement("BookParticipant");
XElement xeBookParticipant = new XElement("BookParticipant");
XDocument xDocument = new XDocument(new XElement("BookParticipants",
new XElement("BookParticipant",
new XAttribute("type", "Author"),
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz"))));
Console.WriteLine(xDocument.ToString());
//--Calling the ToString Method on an Element Produces the XML Tree
XElement name = new XElement("Name", "Joe");
Console.WriteLine(name.ToString());
//--Console.WriteLine Implicitly Calling the ToString Method on an Element to Produce an XML Tree
XElement name1 = new XElement("Person",
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz"));
Console.WriteLine(name1);
//-- Casting an Element to Its Value’s Data Type Outputs the Value
Console.WriteLine(name);
Console.WriteLine((string)name);
//--Different Node Value Types Retrieved via Casting to the Node Value’s Type
XElement count = new XElement("Count", 12);
Console.WriteLine(count);
Console.WriteLine((int)count);
XElement smoker = new XElement("Smoker", false);
Console.WriteLine(smoker);
Console.WriteLine((bool)smoker);
XElement pi = new XElement("Pi", 3.1415926535);
Console.WriteLine(pi);
Console.WriteLine((double)pi);
DeferredQryProblem();
GenerateXMlFromLinqQry();
}
private static void DeferredQryProblem()
{
XDocument xDocument = new XDocument(
new XElement("BookParticipants",
new XElement("BookParticipant",
new XAttribute("type", "Author"),
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz")),
new XElement("BookParticipant",
new XAttribute("type", "Editor"),
new XElement("FirstName", "Ewan"),
new XElement("LastName", "Buckingham"))));
IEnumerable<XElement> elements =
xDocument.Element("BookParticipants").Elements("BookParticipant");
foreach (XElement element in elements)
{
Console.WriteLine("Source element: {0} : value = {1}",
element.Name, element.Value);
}
foreach (XElement element in elements)
{
Console.WriteLine("Removing {0} = {1} ...", element.Name, element.Value);
element.Remove();
}
Console.WriteLine(xDocument);
foreach (XElement element in elements)
{
Console.WriteLine("Source element: {0} : value = {1}",
element.Name, element.Value);
}
foreach (XElement element in elements.ToArray())
{
Console.WriteLine("Removing {0} = {1} ...", element.Name, element.Value);
element.Remove();
}
Console.WriteLine(xDocument);
}
//-- Creating an Attribute and Adding It to Its Element
private static void CreatingAttribute()
{
XElement xBookParticipant = new XElement("BookParticipant", new XAttribute("type", "Author"));
Console.WriteLine(xBookParticipant);
}
//--Creating a Comment with Functional Construction
private static void CreatingComment()
{
XElement xBookParticipant = new XElement("BookParticipant",
new XComment("This person is retired."));
Console.WriteLine(xBookParticipant);
}
//--Creating a Declaration with Functional Construction
private static void CreateXmlDeclaration()
{
XDocument xDocument = new XDocument(new XDeclaration("1.0", "UTF-8", "yes"),
new XElement("BookParticipant"));
Console.WriteLine(xDocument);
}
private static void GenerateXMlFromLinqQry()
{
BookParticipant[] bookParticipants = new[] {new BookParticipant {FirstName = "Joe", LastName = "Rattz",
ParticipantType = ParticipantTypes.Author},
new BookParticipant {FirstName = "Ewan", LastName = "Buckingham",
ParticipantType = ParticipantTypes.Editor}
};
XElement xBookParticipants =
new XElement("BookParticipants",
bookParticipants.Select(p =>
new XElement("BookParticipant",
new XAttribute("type", p.ParticipantType),
new XElement("FirstName", p.FirstName),
new XElement("LastName", p.LastName))));
Console.WriteLine(xBookParticipants);
}
//-- Obtaining Elements Without Reaching
private static void WithoutReaching()
{
XDocument xDocument = new XDocument(new XElement("BookParticipants",
new XElement("BookParticipant",
new XAttribute("type", "Author"),
new XElement("FirstName", "Joe"),
new XElement("LastName", "Rattz")),
new XElement("BookParticipant",
new XAttribute("type", "Editor"),
new XElement("FirstName", "Ewan"),
new XElement("LastName", "Buckingham"))));
IEnumerable<XElement> elements = xDocument.Descendants("BookParticipant");
foreach (XElement element in elements)
{
Console.WriteLine("Element: {0} : value = {1}",
element.Name, element.Value);
}
IEnumerable<XElement> elements1 = xDocument.Descendants("BookParticipant")
.Where(e => ((string)e.Element("FirstName")) == "Ewan");
foreach (XElement element1 in elements1)
{
Console.WriteLine("Element: {0} : value = {1}",
element1.Name, element1.Value);
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Xml.Linq;
namespace LinqToXmlTest
{
public partial class _Default : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void ReadXml()
{
XDocument xdocument = XDocument.Load(Server.MapPath("People.xml"));
var persons = from person in xdocument.Descendants("Person")
select new
{
Name = person.Element("Name").Value,
City = person.Element("City").Value,
Age = person.Element("Age").Value
};
litResults.Text = "";
foreach (var person in persons)
{
litResults.Text = litResults.Text + "Name: " + person.Name + "<br/>";
litResults.Text = litResults.Text + "City: " + person.City + "<br/>";
litResults.Text = litResults.Text + "Age: " + person.Age + "<br/><br/>";
}
if (litResults.Text == "")
litResults.Text = "No Results...";
}
protected void butAdd_Click(object sender, EventArgs e)
{
try
{
if (txtName.Text == "" || txtCity.Text == "" || txtAge.Text == "")
{
lblStatus.ForeColor = System.Drawing.Color.Red;
lblStatus.Text = "Please Complete the form";
}
else
{
XDocument xdocumnet = XDocument.Load(Server.MapPath("People.xml"));
xdocumnet.Element("Persons").Add(new XElement("Person",
new XElement("Name", txtName.Text),
new XElement("City", txtCity.Text),
new XElement("Age", txtAge.Text)));
xdocumnet.Save(Server.MapPath("People.xml"));
lblStatus.ForeColor = System.Drawing.Color.Green;
lblStatus.Text = "Data Successfully loaded to xml file";
txtName.Text = "";
txtCity.Text = "";
txtAge.Text = "";
ReadXml();
}
}
catch
{
lblStatus.ForeColor = System.Drawing.Color.Red;
lblStatus.Text = "Sorry unable to precess request.Please try again";
}
}
protected void butRead_Click(object sender, EventArgs e)
{
ReadXml();
lblStatus.Text = "";
}
protected void btnUpdate_Click(object sender, EventArgs e)
{
try
{
if (txtName.Text == "" || txtCity.Text == "" || txtAge.Text == "")
{
lblStatus.ForeColor = System.Drawing.Color.Red;
lblStatus.Text = "Please enter all details in the form";
}
else
{
XDocument xdocument = XDocument.Load(Server.MapPath("People.xml"));
var persondata = (from person in xdocument.Descendants("Person")
where person.Element("Name").Value.Equals(txtName.Text)
select person).Single();
persondata.Element("City").Value = txtCity.Text;
persondata.Element("Age").Value = txtAge.Text;
xdocument.Save(Server.MapPath("People.xml"));
lblStatus.ForeColor = System.Drawing.Color.Green;
lblStatus.Text = "The data updated successfully";
ReadXml();
}
}
catch(Exception ex)
{
lblStatus.ForeColor = System.Drawing.Color.Red;
lblStatus.Text = ex.Message;
}
}
protected void btnDelete_Click(object sender, EventArgs e)
{
try
{
if (txtName.Text == "")
{
lblStatus.ForeColor = System.Drawing.Color.Red;
lblStatus.Text = "Please enter the name of the person to delete...";
}
else
{
XDocument xdocument = XDocument.Load(Server.MapPath("People.xml"));
var persondata = (from person in xdocument.Descendants("Person")
where person.Element("Name").Value.Equals(txtName.Text)
select person).Single();
persondata.Remove();
xdocument.Save(Server.MapPath("People.xml"));
lblStatus.ForeColor = System.Drawing.Color.Green;
lblStatus.Text = "The data deleted successfully...";
txtName.Text = "";
txtCity.Text = "";
txtAge.Text = "";
ReadXml();
}
}
catch (Exception ex)
{
lblStatus.ForeColor = System.Drawing.Color.Red;
lblStatus.Text = ex.Message;
}
}
}
}
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