expr Property
Gets or sets the XML Path Language (XPath) expression.
Script Syntax
strExpression = objXMLDOMSelection.expr; objXMLDOMSelection.expr = strExpression;
Example
var xmlDoc = new ActiveXObject("Msxml2.DOMDocument.5.0"); var selection; xmlDoc.loadXML("<Customer><Name>Microsoft</Name></Customer>"); if (xmlDoc.parseError.errorCode <> 0) { var myErr = xmlDoc.parseError; alert("You have error " + myErr.reason); } else { xmlDoc.setProperty("SelectionLanguage", "XPath"); selection = xmlDoc.selectNodes("Customer/Name"); alert(selection.expr + " -- " + selection.item(0).xml);
This displays "Customer/Name -- <Name> Microsoft</Name>".
selection.expr = "/Customer";
The selection is immediately refreshed with a list corresponding to the new expression.
alert(selection.expr + " -- " + selection.item(0).xml); }
This displays "/Customer -- <Customer><Name> Microsoft</Name></Customer>".
Visual Basic Syntax
strExpression = objXMLDOMSelection.expr objXMLDOMSelection.expr = strExpression
Example
Dim xmlDoc As New Msxml2.DOMDocument50 Dim selection As Msxml2.IXMLDOMSelection xmlDoc.loadXML ("<Customer><Name>Microsoft</Name></Customer>") If (xmlDoc.parseError.errorCode <> 0) Then Dim myErr Set myErr = xmlDoc.parseError MsgBox("You have error " & myErr.reason) Else xmlDoc.setProperty "SelectionLanguage", "XPath" Set selection = xmlDoc.selectNodes("Customer/Name") MsgBox selection.expr + " -- " + selection.Item(0).xml
This displays "Customer/Name -- <Name> Microsoft</Name>".
selection.expr = "/Customer"
The selection is immediately refreshed with a list corresponding to the new expression.
MsgBox selection.expr + " -- " + selection.Item(0).xml End If
This displays "/Customer -- <Customer><Name> Microsoft</Name></Customer>".
C/C++ Syntax
HRESULT get_expr(BSTR* expression); HRESULT put_expr(BSTR expression);
Parameters
- expression [out, retval][in]
- A string specifying the XPath expression to be returned or set.
C/C++ Return Values
- S_OK
- The value returned if method is successful.
E_FAIL and formatted error message through IErrorInfo
if expression is invalid.
Example
The following C/C++ example shows the resetting of the selected nodes list if the expr
property is changed.
#import "msxml3.dll" using namespace MSXML2; #define CHECK_AND_RELEASE(pInterface) \ if(pInterface) \ {\ pInterface->Release();\ pInterface = NULL;\ }\ #define RELEASE(pInterface) \ {\ pInterface->Release();\ pInterface = NULL;\ }\ BOOL DOMSelectionExprDemo() { BOOL bResult = FALSE; short sResult = FALSE; long lvalue; IXMLDOMSelection *pIXMLDOMSelection=NULL; IXMLDOMDocument2 *pIXMLDOMDocument2=NULL; HRESULT hr; BSTR bstrValue; try { hr=CoCreateInstance(CLSID_DOMDocument, NULL, CLSCTX_SERVER, IID_IXMLDOMDocument2, (LPVOID*)(&pIXMLDOMDocument2)); SUCCEEDED(hr) ? 0 : throw hr; if(pIXMLDOMDocument2) { hr=pIXMLDOMDocument2->put_async(VARIANT_FALSE); if(SUCCEEDED(hr)) { hr=pIXMLDOMDocument2->load(_variant_t( _T("d:\\inetpub\\wwwroot\\sample.xml")), &sResult); if(SUCCEEDED(hr) && (sResult==VARIANT_TRUE)) { hr=pIXMLDOMDocument2->selectNodes( _T("*/BOOK[TITLE='Lover Birds']"), (IXMLDOMNodeList**)&pIXMLDOMSelection); if(SUCCEEDED(hr)) { if(SUCCEEDED(hr) && pIXMLDOMSelection) { hr = pIXMLDOMSelection->get_expr(&bstrValue); if(SUCCEEDED(hr)) { ::MessageBox(NULL, bstrValue, _T("Current Expression"), MB_OK); bResult=TRUE; hr = pIXMLDOMSelection->get_length(&lvalue); hr = pIXMLDOMSelection->put_expr(_T("*/BOOK")); hr = pIXMLDOMSelection->get_length(&lvalue); } RELEASE(pIXMLDOMSelection); } } } } RELEASE(pIXMLDOMDocument2); } } catch(...) { CHECK_AND_RELEASE(pIXMLDOMSelection); CHECK_AND_RELEASE(pIXMLDOMDocument2); DisplayErrorToUser(); } return bResult; }
File Name: d:\\inetpub\\wwwroot\\sample.xml
<?xml version='1.0'?> <COLLECTION xmlns:dt="urn:schemas-microsoft-com:datatypes"> <DATE dt:dt="datetime">1998-10-13T15:56:00</DATE> <BOOK> <TITLE>Lover Birds</TITLE> <AUTHOR>Cynthia Randall</AUTHOR> <PUBLISHER>Lucerne Publishing</PUBLISHER> </BOOK> <BOOK> <TITLE>The Sundered Grail</TITLE> <AUTHOR>Eva Corets</AUTHOR> <PUBLISHER>Lucerne Publishing</PUBLISHER> </BOOK> </COLLECTION>
Output (in a message box)
The first message box will display "1".
The second message box will display "2". When the expression changes, the nodes in the selection are recomputed using the new expression. No changes are made to the context
property.
Remarks
Immediately setting a new expression resets the state of this node list to the beginning unless the expression is invalid and an error is returned, in which case it has no effect. It does not reset the context
property.
To view reference information for Visual Basic, C/C++, or Script only, click the Language Filter button in the upper-left corner of the page.
See Also
Applies to: IXMLDOMSelection