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Delphi XE2 Parsing XML with TXMLDocument

Posted on 2014-02-17
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Last Modified: 2014-02-19
Hi
 I am trying to parse an XML file using TXMLDocument and Delphi XE2. I am new to XML with Delphi and having much trouble accessing the attribute values from this file:

http://www.ecb.europa.eu/stats/eurofxref/eurofxref-daily.xml

I have no trouble reaching the first level <Cube> and can return an IXMLNode instance but I cannot get to anything below that ie. second and third level child nodes (both <Cube>) and their attribute values.

Basically I'm doing this, for example, to get the "time" attribute value from the second level <Cube> ...

      StartingItemNode := XMLDocument.DocumentElement.ChildNodes['Cube'];
      aNode := StartingItemNode;
      sDATE := aNode.ChildNodes['Cube'].Attributes['time'];

... line 1 is fine but sDATE in line 3 is always null.

Please could anyone tell me where this is going wrong ?

thanks and best wishes

RR
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Question by:RetroRocker
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3 Comments
 
LVL 27

Accepted Solution

by:
Sinisa Vuk earned 2000 total points
ID: 39865910
This is my example:

uses ComObj, MSXML;

....
var
  XMLDOMDocument  : IXMLDOMDocument;
  XMLDOMNode      : IXMLDOMNode;
  XMLDOMNodeList  : IXMLDOMNodeList;
  aXMLDOMNode     : IXMLDOMNode;
  xml : TStringList;
  i: Integer;
begin
  xml := TStringList.Create;
  try
    xml.LoadFromFile('C:\Delphi6\Projects\Temp\test\eurofxref-daily.xml');

    XMLDOMDocument:=CoDOMDocument.Create;
    try
      XMLDOMDocument.loadXML(xml.Text);

      if (XMLDOMDocument.parseError.ErrorCode<>0) then
        raise Exception.CreateFmt('Error in Xml Data %s', [XMLDOMDocument.parseError]);
        
      XMLDOMNode := XMLDOMDocument.selectSingleNode('//gesmes:Envelope/Cube/Cube');
      if XMLDOMNode<>nil then
      begin
        ListBox3.Items.Add(XMLDOMNode.attributes.getNamedItem('time').Text);
        XMLDOMNodeList := XMLDOMNode.selectNodes('.//Cube');

        if XMLDOMNodeList<>nil then
        begin
          for i:=0 to XMLDOMNodeList.length-1 do
          begin
            aXMLDOMNode := XMLDOMNodeList.item[i];
            ListBox3.Items.Add(aXMLDOMNode.attributes.getNamedItem('currency').Text + ' = '+
              aXMLDOMNode.attributes.getNamedItem('rate').Text);
          end;
        end;
      end;
    finally
      XMLDOMDocument:=nil;
    end;
  finally
    xml.Free;
  end;

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Main goal is to select main Cube node to get time attribute. The select relative node Cube and get list of sub-nodes.
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Author Closing Comment

by:RetroRocker
ID: 39868697
What can I say ...  a thoroughly detailed, fully working solution ... I am genuinely very grateful :-)
I probably would have continued to struggle with TXMLDocument to parse this file and even now, I have still not found a way to do it. I believe that TXMLDocument is a 'wrapper' for MSXML and I applaud your ingenuity in employing MSXML directly. It seems to have methods which are more suitable for addressing the nodes in this case. With TXMLDocument I still have never been able to get beyond the first level of <Cube> in this file.
Once again, many thanks for your time and effort with this.

RR
0
 
LVL 27

Expert Comment

by:Sinisa Vuk
ID: 39869633
Thanks. I'm glad to help you. Yes, this is MS parser - and is fast enough, but depends on external dll (part of windows). But there are more other third part components like this one:
http://www.kluug.net/oxml.php
Look at Performance tab.
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