ALV USING FM(FIELDCATALOG_MERGE)

Question

What is the purpose of fm
"REUSE_ALV_FIELDCATALOG_MERGE"
explain briefly with sample code.

Answer 1

Hi,
Using REUSE_ALV_FIELDCATALOG_MERGE can automatically determine the fieldstructure from this source program, no need to maunally build fieldcatalog for the fields defined in the internal table.
REPORT Z_ALV_SIMPLE_EXAMPLE_WITH_ITAB .
*data definition
tables:
marav. "Table MARA and table MAKT
* Data to be displayed in ALV
* Using the following syntax, REUSE_ALV_FIELDCATALOG_MERGE can auto-
* matically determine the fieldstructure from this source program
Data:
begin of imat occurs 100,
matnr like marav-matnr, "Material number
maktx like marav-maktx, "Material short text
matkl like marav-matkl, "Material group (so you can test to make
                        " intermediate sums)
ntgew like marav-ntgew, "Net weight, numeric field (so you can test to
                        "make sums)
gewei like marav-gewei, "weight unit (just to be complete)
end of imat.
* Other data needed
* field to store report name
data i_repid like sy-repid.
* field to check table length
data i_lines like sy-tabix.
* Data for ALV display
TYPE-POOLS: SLIS.
data int_fcat type SLIS_T_FIELDCAT_ALV.
select-options:
s_matnr for marav-matnr matchcode object MAT1.
start-of-selection.
* read data into table imat
  select * from marav
  into corresponding fields of table imat
  where
  matnr in s_matnr.
* Check if material was found
  clear i_lines.
  describe table imat lines i_lines.
  if i_lines lt 1.
*   Using hardcoded write here for easy upload
    write: /
    'No materials found.'.
    exit.
  endif.
end-of-selection.
* Now, we start with ALV
* To use ALV, we need a DDIC-structure or a thing called Fieldcatalogue.
* The fieldcatalouge can be generated by FUNCTION
* 'REUSE_ALV_FIELDCATALOG_MERGE' from an internal table from any
* report source, including this report.
* The only problem one might have is that the report and table names
* need to be in capital letters. (I had it :-( )
* Store report name
  i_repid = sy-repid.
* Create Fieldcatalogue from internal table
  CALL FUNCTION 'REUSE_ALV_FIELDCATALOG_MERGE'
       EXPORTING
            I_PROGRAM_NAME         = i_repid
            I_INTERNAL_TABNAME     = 'IMAT'  "capital letters!
            I_INCLNAME             = i_repid
       CHANGING
            CT_FIELDCAT            = int_fcat
       EXCEPTIONS
            INCONSISTENT_INTERFACE = 1
            PROGRAM_ERROR          = 2
            OTHERS                 = 3.
*explanations:
*    I_PROGRAM_NAME is the program which calls this function
*    I_INTERNAL_TABNAME is the name of the internal table which you want
*                       to display in ALV
*    I_INCLNAME is the ABAP-source where the internal table is defined
*               (DATA....)
*      CT_FIELDCAT contains the Fieldcatalouge that we need later for
*      ALV display
  IF SY-SUBRC <> 0.
    write: /
    'Returncode',
    sy-subrc,
    'from FUNCTION REUSE_ALV_FIELDCATALOG_MERGE'.
  ENDIF.
*This was the fieldcatlogue
* And now, we are ready to display our list
* Call for ALV list display
  CALL FUNCTION 'REUSE_ALV_LIST_DISPLAY'
       EXPORTING
*            I_CALLBACK_PROGRAM = 'Z_ALV_SIMPLE_EXAMPLE_WITH_ITAB'
            I_CALLBACK_PROGRAM = i_repid
            IT_FIELDCAT        = int_fcat
            I_SAVE             = 'A'
       TABLES
            T_OUTTAB           = imat
       EXCEPTIONS
            PROGRAM_ERROR      = 1
            OTHERS             = 2.
*explanations:
*    I_CALLBACK_PROGRAM is the program which calls this function
*    IT_FIELDCAT (just made by REUSE_ALV_FIELDCATALOG_MERGE) contains
*                 now the data definition needed for display
*    I_SAVE allows the user to save his own layouts
*      T_OUTTAB contains the data to be displayed in ALV
  IF SY-SUBRC <> 0.
    write: /
    'Returncode',
    sy-subrc,
    'from FUNCTION REUSE_ALV_LIST_DISPLAY'.
  ENDIF.
Thanks,
Sriram Ponna.