• Articolo

XElement.Parse Method (String, LoadOptions)

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

Load an XElement from a string that contains XML, 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 Parse ( _
    text As String, _
    options As LoadOptions _
) As XElement

public static XElement Parse(
    string text,
    LoadOptions options
)

Parameters

Return Value

Type: System.Xml.Linq.XElement
An XElement populated from the string that contains XML.

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.

Setting SetBaseUri will have no effect when parsing from a String.

The XmlReader may have a valid line information or not. If you set SetLineInfo, the line information will be set in the XML tree from the line information that is reported by the XmlReader.

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.

LINQ to XML's loading functionality is built upon XmlReader. Therefore, you might catch any exceptions that are thrown by the XmlReader.Create overload methods and the XmlReader methods that read and parse the document.

Examples

The following example parses a string into an XElement 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 whiteSpaceNodes As Integer

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

Dim xmlTree2 As XElement = XElement.Parse("<Root> <Child> </Child> </Root>", LoadOptions.PreserveWhitespace)
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();
int whiteSpaceNodes;

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


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