• Articolo

XElement.Load Method (TextReader, LoadOptions)

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Loads an XElement from a TextReader, optionally preserving white space and retaining line information.

Namespace:  System.Xml.Linq
Assembly:  System.Xml.Linq (in System.Xml.Linq.dll)

Syntax

'Declaration
Public Shared Function Load ( _
    textReader As TextReader, _
    options As LoadOptions _
) As XElement

public static XElement Load(
    TextReader textReader,
    LoadOptions options
)

Parameters

Return Value

Type: System.Xml.Linq.XElement
An XElement that contains the XML that was read from the specified TextReader.

Remarks

If the source XML is indented, setting the PreserveWhitespace flag in options causes the reader to read all white space in the source XML. Nodes of type XText are created for both significant and insignificant white space.

If the source XML is indented, not setting the PreserveWhitespace flag in options causes the reader to ignore all of the insignificant white space in the source XML. The XML tree is created without any text nodes for insignificant white space.

If the source XML is not indented, setting the PreserveWhitespace flag in options has no effect. Significant white space is still preserved, and there are no spans of insignificant white space that could cause the creation of more white space text nodes.

Use Parse to create an XElement from a string that contains XML.

Setting SetBaseUri will have no effect when loading from a TextReader.

There is a performance penalty if you set the SetLineInfo flag.

The line information is accurate immediately after loading the XML document. If you modify the XML tree after loading the document, the line information may become meaningless.

Examples

The following example loads an XElement from a StringReader in two different ways: preserving white space, and not preserving white space. It then uses a query to determine the number of white space nodes in the resulting XML tree.

Dim output As New StringBuilder
Dim sr As TextReader
Dim whiteSpaceNodes As Integer

sr = New StringReader("<Root> <Child> </Child> </Root>")
Dim xmlTree1 As XElement = XElement.Load(sr, LoadOptions.None)
sr.Close()
whiteSpaceNodes = xmlTree1 _
    .DescendantNodesAndSelf() _
    .OfType(Of XText)() _
    .Where(Function(tNode As XNode) tNode.ToString().Trim().Length = 0) _
    .Count()
output.Append("Count of white space nodes (not preserving whitespace): {0}", whiteSpaceNodes)
output.Append(Environment.NewLine)

sr = New StringReader("<Root> <Child> </Child> </Root>")
Dim xmlTree2 As XElement = XElement.Load(sr, LoadOptions.PreserveWhitespace)
sr.Close()
whiteSpaceNodes = xmlTree2 _
    .DescendantNodesAndSelf() _
    .OfType(Of XText)() _
    .Where(Function(tNode As XNode) tNode.ToString().Trim().Length = 0) _
    .Count()
output.Append("Count of white space nodes (preserving whitespace): {0}", whiteSpaceNodes)
output.Append(Environment.NewLine)

OutputTextBlock.Text = output.ToString()

StringBuilder output = new StringBuilder();
TextReader sr;
int whiteSpaceNodes;

sr = new StringReader("<Root> <Child> </Child> </Root>");
XElement xmlTree1 = XElement.Load(sr, LoadOptions.None);
sr.Close();
whiteSpaceNodes = xmlTree1
    .DescendantNodesAndSelf()
    .OfType<XText>()
    .Where(tNode => tNode.ToString().Trim().Length == 0)
    .Count();
output.Append("Count of white space nodes (not preserving whitespace): " + whiteSpaceNodes + Environment.NewLine);

sr = new StringReader("<Root> <Child> </Child> </Root>");
XElement xmlTree2 = XElement.Load(sr, LoadOptions.PreserveWhitespace);
sr.Close();
whiteSpaceNodes = xmlTree2
    .DescendantNodesAndSelf()
    .OfType<XText>()
    .Where(tNode => tNode.ToString().Trim().Length == 0)
    .Count();
output.Append("Count of white space nodes (preserving whitespace): " + whiteSpaceNodes + Environment.NewLine);

OutputTextBlock.Text = output.ToString();

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.