What is the correct use of XmlNode.SelectSingleNode(string xpath) in C#?

I'm having trouble dealing with some XML file (which is at the end of this post).

I wrote the following code in order to get Job_Id data related to a given Job_Name pattern whose owner Job_Owner is the user running the probram:

List<String> jobID = new List<String>();
XmlNodeList nodes = xml.SelectNodes("//Job");
foreach (XmlNode node in nodes)
{
    innerNode = node.SelectSingleNode("//Job_Owner"); // SelectSingleNode here always selects the same node, but I thought it should be relative to node, not to nodes
    if (!innerNode.InnerText.Contains(Environment.UserName))
    {
        continue;
    }
    innerNode = node.SelectSingleNode("//Job_Name");
    if (!Regex.IsMatch(innerNode.InnerText, jobNamePattern, RegexOptions.Compiled))
    {
        continue;
    }
    innerNode = node.SelectSingleNode("//Job_Id");
    jobID.Add(innerNode.InnerText);
}

I would expect that node.SelectSingleNode("//Job_Name") seeks for a tag named Job_Name only under the xml code represented by node.

That is not what it seems to be happening, as it always return the same node, doesn't matter at what step of the foreach it is (i.e. the node selected from the nodes changes, but the node.SelectSingleNode("//Job_Name") always r开发者_开发知识库eturn the same content).

What is wrong with this code?

Thanks in advance!

--

The XML File looks like this:

<Data>
    <Job>
        <Job_Id>58282.minerva</Job_Id>
        <Job_Name>sb_net4_L20_sType1</Job_Name>
        <Job_Owner>mgirardis@minerva</Job_Owner>
        <!--more tags-->
    </Job>
    <Job>
        <!--etc etc etc-->
    </Job>
    <!--etc etc etc-->
</Data>

It's because you're using the '//' syntax in XPath. That specific syntax selects the first node in the document named that. Try looking at https://www.w3schools.com/xml/xpath_syntax.asp for information on XPath syntax.

If you're looking for child nodes, try just using the node name (IE: 'Job_Owner' instead of '//Job_Owner')

Infernex87 is correct that Job_Owner is simple and effective for this case. However, if it were not a direct child, you could do:

.//Job_Owner

Just like for directories, . is the current node, so this finds descendants of the current node, rather than the root of the document.

Infernex87 has nailed the reason. Going by your XML, I guess going the LINQ route might be a good option for you. If you wish to start, Scott Gu's blog is a great resource.

we did a big DOM /xML /SQL Routine with maXbox script:

function GetXMLFromURLAdr_IsSame_All(apath: string): boolean;
    var
      xml, node: Olevariant; //IXMLDOMDocument;
      nodes_row, nodes_se, nodex: olevariant;
      i, j: Integer;
      sr1,sr2, basenod, basenod2, filePrefix, mySQL, odbcDSN, Auftrag: string;
    begin
      xml:= CreateOleObject('Microsoft.XMLDOM') as IXMLDocument;
      xml.async:= False;
      if xml.load(apath) then writeln('xml path load success2'); 
      if xml.parseError.errorCode <> 0 then
        writeln('XML Load error:' + xml.parseError.reason);
        basenod:= '/WAB/Auftragsliste/Auftrag';
      nodes_row:= xml.SelectNodes(basenod);
       writeln('total auftrag nodes: '+itoa(nodes_row.length))
       try
       for j:= 0 to nodes_row.length-1 do begin
          //nodes_se:= nodes_row.item[j]
          node:= nodes_row.item[j]

          // writeln(node.text)
       sr1:= node.selectSingleNode('.//Lieferanschrift/Ort').text
       sr1:= sr1 + node.selectSingleNode('.//Lieferanschrift/Strasse').text 
       sr2:= node.selectSingleNode('.//Rechnungsanschrift/Ort').text;
       sr2:= sr2 + node.selectSingleNode('.//Rechnungsanschrift/Strasse').text;
       writeln(node.selectSingleNode('.//Auftragskopf/FremdlieferscheinNr').text);
       Auftrag:= node.selectSingleNode('.//Auftragskopf/FremdlieferscheinNr').text
       writeln(node.selectSingleNode('.//Auftragskopf/FremdlieferscheinNr').text);


  if ANSICompareText(sr1, sr2) = 0 then begin
      srlist:= FindAllFiles(PDFFILEPATH,'*'+Auftrag+'_??.pdf',true); 
      for it:= 0 to srlist.count-1 do begin
        writeln((srlist.strings[it]));
        if lCopyFile(srlist.strings[it],
           PDFEXPORT+extractfilename(srlist.strings[it]),true) 
               then writeln('copyof=: '+srlist.strings[it]);
      end;  
     srlist.free;
     srlist:= Nil;
     it:=0;
     result:= true;        
   end else begin
     srlist:= FindAllFiles(PDFFILEPATH,'*'+Auftrag+'*.pdf',true); 
     for it:= 0 to srlist.count-1 do begin
       if lCopyFile(srlist.strings[it],
          PDFEXPORT+extractfilename(srlist.strings[it]),true)
         then writeln('copyof<>: '+srlist.strings[it]); 
     end; 
     DeleteFiles(PDFEXPORT, '*RG.pdf');
     DeleteFile(PDFEXPORT+'Special_'+Auftrag+'_ES.pdf');
     srlist.free; 
     result:= false  
   end; 
    //mk change in op
    fileprefix:= 'WAB'; 
    odbcDSN:= 'advance_kmu_loc';

    if filePrefix='WAB' then begin
      mySQL:= 'UPDATE verk_auftrag SET Status = 61 where Auftrag = '+Auftrag;
      writeln('order back: '+
      itoa(MySQLQueryExecute2(mysql, odbcDsn, strtoint(Auftrag),true)));
    end;
    if filePrefix='WEA' then begin
      mySQL:= 'UPDATE verk_auftrag SET Status = 52 where Auftrag = '+Auftrag;
      writeln('order back: '+
      itoa(MySQLQueryExecute2(mysql, odbcDsn, strtoint(Auftrag),true)));
    end; }

   nodes_se:= node.selectNodes('.//Auftragspositionen/Position');
    writeln('total posnod: '+itoa(nodes_se.length))
    for i:= 0 to nodes_se.length - 1 do begin
      node:= nodes_se.item[i];
      writeln('Posit=' + node.text);
    end;//}
    writeln('------------------------');
  end;  //}
  except
    writeln(exceptiontoString(exceptiontype, exceptionparam))
  finally
    xml:= unassigned;
    xml:= NULL;
  end;
end;