Traverse all the nodes of an XML document?

Question

I want to traverse through the entire nodes of an if_ixml_document. which is the best way to do this?

Please find the sample document.

<text>
    <id>
         <guid auto="false">
               432543254543
         </guid>
    </id>
     <title>
         <short_title italics="on">
                <bold language = "german">
                     "Hello"
               </bold>
        </short_title>
     </title> </text>

In this document, i need to traverse through the nodes <text>, <id>, <guid> , <title>, <short_title>, <bold> etc.

Thanks in advance

Regards, Alex

Answer 1

You can find an extensive XML manual on SAP's documentation website (in case the link doesn't work correctly, go to the NetWeaver Developer's Guide on help.sap.com and search for 'xml library').

The chapter 'iXML ABAP Objects Jumpstart' should get you started quickly. The paragraph 'Iterating over the complete DOM-tree' provides the following example code:

data: iterator type ref to if_ixml_node_iterator,
      node     type ref to if_ixml_node.
iterator = document->create_iterator( ).
node = iterator->get_next( ).
while not node is initial.
  * do something with the node
  ...
  node = iterator->get_next( ).
endwhile.

Answer 2

The first step is to parse your XML as follows. You can of course upload the XML from a file into the string, but this is just an example:

data: lr_xml type ref to cl_xml_document.
data: lr_node type ref to if_ixml_node.
data: lv_xml type string.

lv_xml = '<text> <id> <guid auto="false"> 432543254543 </guid> </id> <title> <short_title italics="on"> <bold language = "german"> "Hello"</bold> </short_title> </title> </text>'.

create object lr_xml.

lr_xml->parse_string( lv_xml ).
lr_node = lr_xml->get_first_node( ).

Now you have an instance of IF_XML_NODE that points to the root of your XML document. You can now use the various methods to traverse the XML tree, and get values out of it, using the various methods such as GET_CHILDREN, GET_ATTRIBUTES, GET_NAME etc.

This will be OK for fairly small XML documents, though for efficiency, if you are looking for a specific set of nodes, you may want to look at using an XPATH query.

Answer 3

I hope following example can clarify the situation:

 DATA: lcl_xml_doc TYPE REF TO cl_xml_document,
          lf_node TYPE REF TO if_ixml_node,
          lf_value TYPE string,
          i_xml type string,
          lf_name TYPE string,
      i_xml = 'PUT your XML HERE'.
      CREATE OBJECT lcl_xml_doc.
      IF lcl_xml_doc IS BOUND.
        IF lcl_xml_doc->parse_string( i_xml ) EQ 0.
          lf_node = lcl_xml_doc->m_document.
          IF  lf_node IS NOT INITIAL. 
            lf_iterator = lf_node->create_iterator( ).
            lf_node = lf_iterator->get_next( ).
            WHILE NOT lf_node IS INITIAL.
              lf_name = lf_node->get_name( ).
              lf_value = lf_node->get_value( ).
              IF lf_name = 'text'.
               " do something for text
               ENDIF.
              ENDIF.
              lf_node = lf_iterator->get_next( ).
            ENDWHILE.
        ENDIF.

Enjoy, Alexander.

Answer 4

Manual xml traversing is error prone and complicated in changing environments. You may want to check whether you really need a direct code traversal.

With the help of (XSLT) transformations you are able to convert XML into ABAP structured types. XPath is supported.

Declaration, test and debugging of transformations is done using the Transformation Editor opened by transaction STRANS.

XSLT is available as transformation type: ABAP XSLT Transformation

In your ABAP Code you will just call the language element CALL TRANSFORMATION and the data is ready to process in your target structure afterwards: ABAP Statement: 'CALL TRANSFORMATION'

Answer 5

You can use the DocumentTraversal interface which should be implemented by any DOM library (Xerces has it):

Document doc = ...;
NodeIterator i = ((DocumentTraversal) doc).createNodeIterator(doc, 
       NodeFilter.SHOW_ELEMENT, null, false);
Element e = null;
while ((e = (Element) i.nextNode()) != null) {
    // do stuff with element
}