How to handle field symbols internal table values?

Question

HI all,
          I declared field string as below.The below code is working fine.
Data : ITAB TYPE STANDARD TABLE OF YAPOPLN, (Custom table).
          wa_itab like line of ITAB.
field-symbol : <fs> type ITAB.
ASSIGN PARAM TO <FS>
LOOP AT <FS> INTO WA_ITAB.
WRITE:/ 'ABC'.
ENDLOOP.
But my requirement is that I dont want all the fields of the table YAPOPLN.My output contains only 2 fields of the table YAPOPLN,which contains total 4 fields.According to my requirement only 2 fields will be getting into one parameter PARAM(this is function module parameter,which is from ALV classes) from the user entered output,which contains only 2 fields.So the above code is not working properly because wa_itab contains 4 fields and giving short dump.
If I am declaring the internal table with the required fields(only 2 fields) and referring that internal table to field symbol <FS>
Data : BEGIN OF ITAB1 OCCURS 0,
         FIELD1 LIKE YAPOPLN-FIELD1,
         FIELD2 LIKE YAPOPLN-FIELD2,
         END OF ITAB1.
field-symbol : <fs> LIKE ITAB1 OR  <FS> TYPE ANY.
DATA :WA_ITAB1 LIKE LINE OF ITAB1.
ASSIGN PARAM TO <FS>
LOOP AT <FS> INTO WA_ITAB.
WRITE:/ 'ABC'.
ENDLOOP.
But when I am compiling this code i am getting the below error.I am gettting the same below error when even <FS> is also declared as <FS> TYPE ANY.
.'FS' is not an internal table or defined in TABLES.
Can anyone help me in this regard?
Thanks,
Balaji

Answer 1

Hello,
Try this way:
If both the type of internal tables are same then you can directly assign dynamic internal table to static internal table.
itab = <itab>.
Suppose you have field symbol internal table <itab> which is different in structure from ITAB.
Now, you can create <wa> as follow:
FIELD-SYMBOLS <wa>.
DATA wa TYPE REF TO DATA.
CREATE DATA wa TYPE LINE OF <itab>.
ASSIGN wa->* to <wa>.
This way your work area is read.
Using [ASSIGN COMPONENT|http://help.sap.com/saphelp_nw04/helpdata/EN/fc/eb3923358411d1829f0000e829fbfe/content.htm] syntax you can read required component of <wa>.
Finally you can use that value to load static internal table.
You can also refer to my thread on [Dynamic table|Re: Creating Dynamic table].
Hope this helps!
Thanks,
Augustin.
Edited by: Augustarian on Aug 20, 2009 10:06 AM