Preserve whitespace in xml parsing

Question

Hi,
I am using PL.SQL to parse XML documents using DBMS_XMLDOM..
and using XMLTYPE...
Below is the code...
set serveroutput on
declare
     var_xmltype     XMLType;
     doc          dbms_xmldom.DOMDocument;
     ndoc          dbms_xmldom.DOMNode;
     docelem          dbms_xmldom.DOMElement;
     node          dbms_xmldom.DOMNode;
     l_loop_group_8_node_list          dbms_xmldom.DOMNodelist;
     l_loop_group_8_node_list_count          number(10);
     l_loop_group_8_sub_node_list          dbms_xmldom.DOMNodelist;
     l_lin_segment_node          dbms_xmldom.DOMNode;
     l_lin_segment_child_node     dbms_xmldom.DOMNode;
     l_loop_group_8_count number(10);
     p_clob_message CLOB;
     l_clob_message CLOB;
     CURSOR c is SELECT * from emx_message_storage where emx_message_id = '170615';
begin
for r in c loop
p_clob_message := r.message_clob;
end loop;
     var_xmltype := xmltype (p_clob_message);
     -- Create DOMDocument handle
     doc :=     dbms_xmldom.newDOMDocument (var_xmltype);
     ndoc := dbms_xmldom.makeNode (doc);
     docelem := dbms_xmldom.getDocumentElement (doc);
     -- Access Loop-Group_8 Node:
     l_loop_group_8_node_list := dbms_xmldom.getElementsByTagName(docelem, 'Loop-Group_8');
     l_loop_group_8_node_list_count := dbms_xmldom.getlength (l_loop_group_8_node_list);
     --dbms_output.put_line ('Number of Loop-Group_8 Nodes =' || l_loop_group_8_node_list_count);
     FOR l_ka IN 0..(l_loop_group_8_node_list_count-1) LOOP
          -- Get ith Loop-Group_8 node.
          node := dbms_xmldom.item (l_loop_group_8_node_list, l_ka);
          l_loop_group_8_sub_node_list := dbms_xmldom.getChildNodes (node);
          -- Get Segment-LIN
          l_lin_segment_node := dbms_xmldom.item (l_loop_group_8_sub_node_list,0);
          l_lin_segment_child_node := dbms_xmldom.getFirstChild (l_lin_segment_node);
          --dbms_output.put_line ('Before,' || dbms_xmldom.getNodeName (l_lin_segment_child_node) || ' = '  || dbms_xmldom.getNodeValue (DBMS_XMLDOM.getFirstChild(l_lin_segment_child_node)));
          dbms_xmldom.setNodeValue (DBMS_XMLDOM.getFirstChild(l_lin_segment_child_node), l_ka+1);
          --dbms_output.put_line ('After,' || dbms_xmldom.getNodeName (l_lin_segment_child_node) || ' = '  || dbms_xmldom.getNodeValue (DBMS_XMLDOM.getFirstChild(l_lin_segment_child_node)));
     END LOOP;
     DBMS_LOB.CreateTemporary(l_clob_message, TRUE);
     dbms_xmldom.writeToClob (doc, l_clob_message);
     dbms_xmldom.freeDocument(doc);
     update emx_message_storage set message_clob = l_clob_message where emx_message_id = '149329';
end;
The code works fine.. except for the fact that when in the input XML message i get one element as
<Element-3042> </Element-3042>
it converts it to
<Element-3042/>
The whitespace is removed...
I tried using the xml parser method...and whitespacepreserver optioin...but it creates some extra lines...
Which i dont want.
Please suggest.
Thanks,
Rosh

Answer 1

Difficult to read non-formatted code, so pardon not looking at it and trying to spot the problem/error. However, whitespaces seem to work fine for me (tested on 10.2.0.4). Note the resulting XML for a string value, a whitespace value and a null.
SQL> create table foo_tab( attr1 number, attr2 varchar2(10) );
Table created.
SQL>
SQL> insert into foo_tab values( 1, 'test 123' );
1 row created.
SQL> insert into foo_tab values( 2, ' ' );
1 row created.
SQL> insert into foo_tab values( 3, null );
1 row created.
SQL> commit;
Commit complete.
SQL>
SQL> col XML format a50
SQL> select
  2          XmlElement( "Row",
  3                  XmlForest(
  4                          attr1 as "Name",
  5                          attr2 as "Value"
  6                  )
  7          )               as XML
  8  from       foo_tab
  9  /
XML
<Row><Name>1</Name><Value>test 123</Value></Row>
<Row><Name>2</Name><Value> </Value></Row>
<Row><Name>3</Name></Row>
SQL>