Export (0) Print
Expand All

XContainer.AddFirst Method (Object())

Adds the specified content as the first children of this document or element.

Namespace:  System.Xml.Linq
Assemblies:   System.Xml.Linq (in System.Xml.Linq.dll)
  System.Xml.XDocument (in System.Xml.XDocument.dll)

'Declaration
Public Sub AddFirst ( _
	ParamArray content As Object() _
)

Parameters

content
Type: System.Object()

A parameter list of content objects.

ExceptionCondition
InvalidOperationException

The parent is Nothing.

This method adds the new content before the existing content of the XContainer.

For details about the valid content that can be passed to this function, see Valid Content of XElement and XDocument Objects.

This method will raise the Changed and the Changing events.

The following example creates two XML trees, and uses this method to add an XElement object as the first element to one of them. It also adds the results of a LINQ query to the XML tree.

Dim srcTree As XElement = _ 
        <Root>
            <Element1>1</Element1>
            <Element2>2</Element2>
            <Element3>3</Element3>
            <Element4>4</Element4>
            <Element5>5</Element5>
        </Root>

Dim xmlTree As XElement = _ 
        <Root>
            <Child1>1</Child1>
            <Child2>2</Child2>
            <Child3>3</Child3>
            <Child4>4</Child4>
            <Child5>5</Child5>
        </Root>

xmlTree.AddFirst(New XElement("NewChild", "new content"))
xmlTree.AddFirst( _
    From el In srcTree.Elements() _
    Where CInt(el) > 3 _
    Select el _
)
' Even though Child9 does not exist in srcTree, the following statement will not
' throw an exception, and nothing will be added to xmlTree.
xmlTree.AddFirst(srcTree.<Child9>)
Console.WriteLine(xmlTree)

This example produces the following output:

<Root>
  <Element4>4</Element4>
  <Element5>5</Element5>
  <NewChild>new content</NewChild>
  <Child1>1</Child1>
  <Child2>2</Child2>
  <Child3>3</Child3>
  <Child4>4</Child4>
  <Child5>5</Child5>
</Root>

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
Show:
© 2015 Microsoft