Articolo
11/17/2011

XDocumentType Class

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

Represents an XML Document Type Definition (DTD).

Inheritance Hierarchy

System.Object
  System.Xml.Linq.XObject
    System.Xml.Linq.XNode
      System.Xml.Linq.XDocumentType

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

Syntax

'Declaration
Public Class XDocumentType _
    Inherits XNode

public class XDocumentType : XNode

The XDocumentType type exposes the following members.

Constructors

	Name	Description
	XDocumentType(XDocumentType)	Initializes an instance of the XDocumentType class from another XDocumentType object.
	XDocumentType(String, String, String, String)	Initializes an instance of the XDocumentType class.

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Properties

	Name	Description
	BaseUri	Gets the base URI for this XObject. (Inherited from XObject.)
	Document	Gets the XDocument for this XObject. (Inherited from XObject.)
	InternalSubset	Gets or sets the internal subset for this Document Type Definition (DTD).
	Name	Gets or sets the name for this Document Type Definition (DTD).
	NextNode	Gets the next sibling node of this node. (Inherited from XNode.)
	NodeType	Gets the node type for this node. (Overrides XObject.NodeType.)
	Parent	Gets the parent XElement of this XObject. (Inherited from XObject.)
	PreviousNode	Gets the previous sibling node of this node. (Inherited from XNode.)
	PublicId	Gets or sets the public identifier for this Document Type Definition (DTD).
	SystemId	Gets or sets the system identifier for this Document Type Definition (DTD).

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Methods

	Name	Description
	AddAfterSelf(Object)	Adds the specified content immediately after this node. (Inherited from XNode.)
	AddAfterSelf(array<Object[])	Adds the specified content immediately after this node. (Inherited from XNode.)
	AddAnnotation	Adds an object to the annotation list of this XObject. (Inherited from XObject.)
	AddBeforeSelf(Object)	Adds the specified content immediately before this node. (Inherited from XNode.)
	AddBeforeSelf(array<Object[])	Adds the specified content immediately before this node. (Inherited from XNode.)
	Ancestors()	Returns a collection of the ancestor elements of this node. (Inherited from XNode.)
	Ancestors(XName)	Returns a filtered collection of the ancestor elements of this node. Only elements that have a matching XName are included in the collection. (Inherited from XNode.)
	Annotation(Type)	Gets the first annotation object of the specified type from this XObject. (Inherited from XObject.)
	Annotation<T>()	Get the first annotation object of the specified type from this XObject. (Inherited from XObject.)
	Annotations(Type)	Gets a collection of annotations of the specified type for this XObject. (Inherited from XObject.)
	Annotations<T>()	Gets a collection of annotations of the specified type for this XObject. (Inherited from XObject.)
	CreateReader()	Creates an XmlReader for this node. (Inherited from XNode.)
	CreateReader(ReaderOptions)	Creates an XmlReader for this node. (Inherited from XNode.)
	ElementsAfterSelf()	Returns a collection of the sibling elements after this node, in document order. (Inherited from XNode.)
	ElementsAfterSelf(XName)	Returns a filtered collection of the sibling elements after this node, in document order. Only elements that have a matching XName are included in the collection. (Inherited from XNode.)
	ElementsBeforeSelf()	Returns a collection of the sibling elements before this node, in document order. (Inherited from XNode.)
	ElementsBeforeSelf(XName)	Returns a filtered collection of the sibling elements before this node, in document order. Only elements that have a matching XName are included in the collection. (Inherited from XNode.)
	Equals(Object)	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	Finalize	Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	IsAfter	Determines if the current node appears after a specified node in terms of document order. (Inherited from XNode.)
	IsBefore	Determines if the current node appears before a specified node in terms of document order. (Inherited from XNode.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	NodesAfterSelf	Returns a collection of the sibling nodes after this node, in document order. (Inherited from XNode.)
	NodesBeforeSelf	Returns a collection of the sibling nodes before this node, in document order. (Inherited from XNode.)
	Remove	Removes this node from its parent. (Inherited from XNode.)
	RemoveAnnotations(Type)	Removes the annotations of the specified type from this XObject. (Inherited from XObject.)
	RemoveAnnotations<T>()	Removes the annotations of the specified type from this XObject. (Inherited from XObject.)
	ReplaceWith(Object)	Replaces this node with the specified content. (Inherited from XNode.)
	ReplaceWith(array<Object[])	Replaces this node with the specified content. (Inherited from XNode.)
	ToString()	Returns the indented XML for this node. (Inherited from XNode.)
	ToString(SaveOptions)	Returns the XML for this node, optionally disabling formatting. (Inherited from XNode.)
	WriteTo	Write this XDocumentType to an XmlWriter. (Overrides XNode.WriteTo(XmlWriter).)

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Events

	Name	Description
	Changed	Raised when this XObject or any of its descendants have changed. (Inherited from XObject.)
	Changing	Raised when this XObject or any of its descendants are about to change. (Inherited from XObject.)

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Extension Methods

	Name	Description
	CreateNavigator()	Overloaded. Creates an XPathNavigator for an XNode. (Defined by Extensions.)
	CreateNavigator(XmlNameTable)	Overloaded. Creates an XPathNavigator for an XNode. The XmlNameTable enables more efficient XPath expression processing. (Defined by Extensions.)
	XPathEvaluate(String)	Overloaded. Evaluates an XPath expression. (Defined by Extensions.)
	XPathEvaluate(String, IXmlNamespaceResolver)	Overloaded. Evaluates an XPath expression, resolving namespace prefixes using the specified IXmlNamespaceResolver. (Defined by Extensions.)
	XPathSelectElement(String)	Overloaded. Selects an XElement using a XPath expression. (Defined by Extensions.)
	XPathSelectElement(String, IXmlNamespaceResolver)	Overloaded. Selects an XElement using a XPath expression, resolving namespace prefixes using the specified IXmlNamespaceResolver. (Defined by Extensions.)
	XPathSelectElements(String)	Overloaded. Selects a collection of elements using an XPath expression. (Defined by Extensions.)
	XPathSelectElements(String, IXmlNamespaceResolver)	Overloaded. Selects a collection of elements using an XPath expression, resolving namespace prefixes using the specified IXmlNamespaceResolver. (Defined by Extensions.)

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Explicit Interface Implementations

	Name	Description
	IXmlLineInfo.HasLineInfo	Gets a value indicating whether or not this XObject has line information. (Inherited from XObject.)
	IXmlLineInfo.LineNumber	Gets the line number that the underlying XmlReader reported for this XObject. (Inherited from XObject.)
	IXmlLineInfo.LinePosition	Gets the line position that the underlying XmlReader reported for this XObject. (Inherited from XObject.)

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Remarks

Data Type Definitions (DTD) in XML are a way to do the following:

Validate XML trees to a limited extent.
Expand entities, which is a form of text replacement.
Supply default attributes.

This class represents the XML concept of a DTD.

DTD support in LINQ to XML is limited.

LINQ to XML will expand internal entities by default, but it will not resolve external entity references unless an XmlReader with an associated XmlResolver is used to load the XML tree.

LINQ to XML will not validate a document against a DTD, but you can use a validating XmlReader to perform DTD validation if necessary.

When a document contains entity references that are defined in a DTD, the references are expanded upon creation of the XML tree. However, when you serialize or save the XML tree, the content of the expanded entities is preserved; the entity references are not.

Default attributes from the DTD will be materialized as regular attributes in the XML tree. After a default attribute from the DTD is materialized, there is no way to determine that the attribute was a default attribute from the DTD.

You can populate an XML tree with an XML document that contains an internal DTD. The XML tree will then contain a DocumentType node. When you serialize or save the tree, the internal DTD will also be saved as part of the document.

Examples

The following example shows the use of this property to retrieve the node type for an XDocumentType object.

Dim output As New StringBuilder
Dim internalSubset = _
    "<!ELEMENT Pubs (Book+)>" & Environment.NewLine & _
    "<!ELEMENT Book (Title, Author)>" & Environment.NewLine & _
    "<!ELEMENT Title (#PCDATA)>" & Environment.NewLine & _
    "<!ELEMENT Author (#PCDATA)>"

Dim doc As XDocument = _
    <?xml version="1.0" encoding="utf-8" standalone="yes"?>
    <!--This is a comment.-->
    <?xml-stylesheet href='mystyle.css' title='Compact' type='text/css'?>
    <Pubs>
        <Book>
            <Title>Artifacts of Roman Civilization</Title>
            <Author>Moreno, Jordao</Author>
        </Book>
        <Book>
            <Title>Midieval Tools and Implements</Title>
            <Author>Gazit, Inbar</Author>
        </Book>
    </Pubs>
    <!--This is another comment.-->

doc.FirstNode.AddAfterSelf(New XDocumentType("Pubs", Nothing, Nothing, internalSubset))

output.Append(doc.DocumentType.NodeType.ToString())
output.Append(Environment.NewLine)

OutputTextBlock.Text = output.ToString()

    StringBuilder output = new StringBuilder();
    string internalSubset = @"<!ELEMENT Pubs (Book+)>
<!ELEMENT Book (Title, Author)>
<!ELEMENT Title (#PCDATA)>
<!ELEMENT Author (#PCDATA)>";

    string target = "xml-stylesheet";
    string data = "href=\"mystyle.css\" title=\"Compact\" type=\"text/css\"";

    XDocument doc = new XDocument(
        new XComment("This is a comment."),
        new XProcessingInstruction(target, data),
        new XDocumentType("Pubs", null, null, internalSubset),
        new XElement("Pubs",
            new XElement("Book",
                new XElement("Title", "Artifacts of Roman Civilization"),
                new XElement("Author", "Moreno, Jordao")
            ),
            new XElement("Book",
                new XElement("Title", "Midieval Tools and Implements"),
                new XElement("Author", "Gazit, Inbar")
            )
        ),
        new XComment("This is another comment.")
    );
    doc.Declaration = new XDeclaration("1.0", "utf-8", "true");

    output.Append(doc.DocumentType.NodeType + 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.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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