XDocumentType.SystemId Property

Definition

Namespace:

System.Xml.Linq

Assembly:

System.Xml.XDocument.dll

Source:

XDocumentType.cs

Gets or sets the system identifier for this Document Type Definition (DTD).

public:
 property System::String ^ SystemId { System::String ^ get(); void set(System::String ^ value); };

public string? SystemId { get; set; }

member this.SystemId : string with get, set

Public Property SystemId As String

Property Value

String

A String that contains the system identifier for this Document Type Definition (DTD).

Examples

The following example creates an XML document that refers to an external private DTD. The DTD does not have an internal subset. The call to the XDocumentType constructor reflects the use of the external private DTD. It passes null for the internal subset.

string pubsDtd =  
@"<!ELEMENT Pubs (Book+)>  
<!ELEMENT Book (Title, Author)>  
<!ELEMENT Title (#PCDATA)>  
<!ELEMENT Author (#PCDATA)>";  
File.WriteAllText("Pubs.dtd", pubsDtd);  

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

XDocument doc = new XDocument(  
    new XDocumentType("Pubs", null, "Pubs.dtd", null),  
    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");  
doc.Save("Pubs.xml");  

// Validate Pubs.xml against Pubs.dtd.  
XmlReaderSettings xrs = new XmlReaderSettings();  
xrs.ProhibitDtd = false;  
xrs.ValidationType = ValidationType.DTD;  
xrs.ConformanceLevel = ConformanceLevel.Auto;  
XmlReader xr = XmlReader.Create("Pubs.xml", xrs);  
XDocument doc2 = XDocument.Load(xr);  

XDocumentType dt = doc2.Document.DocumentType;  
Console.WriteLine("SystemId:{0}", dt.SystemId);  

Dim pubsDtd As String = _   
    "<!ELEMENT Pubs (Book+)>" & Environment.NewLine & _  
    "<!ELEMENT Book (Title, Author)>" & Environment.NewLine & _  
    "<!ELEMENT Title (#PCDATA)>" & Environment.NewLine & _  
    "<!ELEMENT Author (#PCDATA)>"  
File.WriteAllText("Pubs.dtd", pubsDtd)  

Dim target As String = "xml-stylesheet"  
Dim data As String = "href='mystyle.css' title='Compact' type='text/css'"  

Dim doc As XDocument = _  
    <?xml version='1.0'?>  
    <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 _  
.AddBeforeSelf(New XDocumentType("Pubs", Nothing, "Pubs.dtd", Nothing))  

doc.Declaration = New XDeclaration("1.0", "utf-8", "true")  
doc.Save("Pubs.xml")  

' Validate Pubs.xml against Pubs.dtd.  
Dim xrs As XmlReaderSettings = New XmlReaderSettings()  
xrs.ProhibitDtd = False  
xrs.ValidationType = ValidationType.DTD  
xrs.ConformanceLevel = ConformanceLevel.Auto  
Dim xr As XmlReader = XmlReader.Create("Pubs.xml", xrs)  
Dim doc2 As XDocument = XDocument.Load(xr)  

Dim dt As XDocumentType = doc2.Document.DocumentType  
Console.WriteLine("SystemId:{0}", dt.SystemId)  

This example produces the following output:

SystemId:Pubs.dtd  

Remarks

If an XML document uses an external private DTD, this property will contain the private identifier of the external DTD.

See also

• LINQ to XML overview