Read data from xml files and populate internal table

Question

Hi.
How to read data from xml files into internal tables?
Can u tell me the classes and methods to read xml data..
Can u  explain it with a sample program...

Answer 1

<pre>DATA itab_accontextdir TYPE TABLE OF ACCONTEXTDIR.
DATA struct_accontextdir LIKE LINE OF itab_accontextdir.
DATA l_o_error TYPE REF TO cx_root.
DATA: filename type string ,
             xmldata type xstring .
DATA: mr      TYPE REF TO if_mr_api.
mr = cl_mime_repository_api=>get_api( ).
mr->get( EXPORTING  i_url     = 'SAP/PUBLIC/BC/xml_files_accontext/xml_accontextdir.xml'
              IMPORTING  e_content = xmldata ).
WRITE xmldata.
TRY.
CALL TRANSFORMATION id
      SOURCE XML xmldata
      RESULT shiva = itab_accontextdir.
  CATCH cx_root INTO l_o_error.
ENDTRY.
LOOP AT itab_accontextdir INTO struct_accontextdir.
    WRITE: / struct_accontextdir-context_id,
           struct_accontextdir-context_name,
           struct_accontextdir-context_type.
    NEW-LINE.
    ENDLOOP.</pre>
<br/>
Description:   
In the above code snippet I am storing the data in an xml file(you know xml is used to store and transport data ) called 'xml_accontextdir.xml' that is uploaded into the MIME repository at path 'SAP/PUBLIC/BC/xml_files_accontext/xml_accontextdir.xml'.
The below API is used to read a file in MIME repo and convert it into a string that is stored in ' xmldata'. (This is just a raw data that is got by appending the each line of  xml file).
mr = cl_mime_repository_api=>get_api( ).
mr->get( EXPORTING  i_url     = 'SAP/PUBLIC/BC/xml_files_accontext/xml_accontextdir.xml'
              IMPORTING  e_content = xmldata ).
    Once the 'xmldata' string is available we use the tranformation to parse the xml string that we have got from the above API and convert it into the internal table.
<pre>TRY.
CALL TRANSFORMATION id
      SOURCE XML xmldata
      RESULT shiva = itab_accontextdir.
  CATCH cx_root INTO l_o_error.
ENDTRY.</pre>
Here the trasnsformation 'id ' is used to conververt the source xml 'xmldata' to resulting internal table itab_accontextdir, that have same structure as our xml file 'xml_accontextdir.xml'.  In the RESULT root of the xml file has to be specified. (In my the root is 'shiva'). 
Things to be taken care:
One of the major problem that occurs when reading the xml file is 'format not compatible with the internal table' that you are reading into internal table.  Iin order to get rid of this issue use one more tranformation to convert the data from the internal table into the xml file.    
<pre>TRY.
      CALL TRANSFORMATION id
        SOURCE shiv = t_internal_tab
        RESULT XML xml.
    CATCH cx_root INTO l_o_error.
  ENDTRY.
  WRITE xml.
  NEW-LINE.</pre>
<br/>
This is the same transformation that we used above but the differnce is that the SOURCE and RESULT parameters are changed the source is now the internal table and result is *xml *string. Use xml browser that is available with the ABAP workbench to read the xml string displayed with proper indentation. In this way we get the format of xml file to be used that is compatable with the given internal table. 
Thank you, Hope this will help you!!!
Edited by: Shiva Prasad L on Jun 15, 2009 7:30 AM
Edited by: Shiva Prasad L on Jun 15, 2009 11:56 AM
Edited by: Shiva Prasad L on Jun 15, 2009 12:06 PM