Doubt in using field catalog merge function

Question

hi all,
    When I am using the function maodule reuse_alv_fieldcatalog_merge for building the field catalog in alv list,it was giving abend message as
'Field catalog is empty'.
     what might be the reason for such message?can some one help me out with the solution to get rid of that.
    I cant populate the catalog manually because I need to display nearly 40 fields in the output.
         Thanks in advance.

Answer 1

hI
Supports the creation of the field catalog for the ALV function modules
based either on a structure or table defined in the ABAP Data
Dictionary, or a program-internal table.
The program-internal table must either be in a TOP Include or its
Include must be specified explicitly in the interface.
The variant based on a program-internal table should only be used for
rapid prototyping since the following restrictions apply:
o Performance is affected since the code of the table definition must
always be read and interpreted at runtime.
o Dictionary references are only considered if the keywords LIKE or
INCLUDE STRUCTURE (not TYPE) are used.
If the field catalog contains more than 90 fields, the first 90 fields
are output in the list by default whereas the remaining fields are only
available in the field selection.
If the field catalog is passed with values, they are merged with the
'automatically' found information.
Below is an example ABAP program which will populate a simple internal table(it_ekpo) with data and
display it using the basic ALV grid functionality(including column total). The example details the main
sections of coding required to implement the ALV grid functionality:
Data declaration
Data retrieval
Build fieldcatalog
Build layout setup
*& Report ZDEMO_ALVGRID *
*& Example of a simple ALV Grid Report *
*& The basic requirement for this demo is to display a number of *
*& fields from the EKKO table. *
REPORT zdemo_alvgrid .
TABLES: ekko.
type-pools: slis. "ALV Declarations
*Data Declaration
TYPES: BEGIN OF t_ekko,
ebeln TYPE ekpo-ebeln,
ebelp TYPE ekpo-ebelp,
statu TYPE ekpo-statu,
aedat TYPE ekpo-aedat,
matnr TYPE ekpo-matnr,
menge TYPE ekpo-menge,
meins TYPE ekpo-meins,
netpr TYPE ekpo-netpr,
peinh TYPE ekpo-peinh,
END OF t_ekko.
DATA: it_ekko TYPE STANDARD TABLE OF t_ekko INITIAL SIZE 0,
wa_ekko TYPE t_ekko.
*ALV data declarations
data: fieldcatalog type slis_t_fieldcat_alv with header line,
gd_tab_group type slis_t_sp_group_alv,
gd_layout type slis_layout_alv,
gd_repid like sy-repid.
*Start-of-selection.
START-OF-SELECTION.
perform data_retrieval.
perform build_fieldcatalog.
perform build_layout.
perform display_alv_report.
*& Form BUILD_FIELDCATALOG
* Build Fieldcatalog for ALV Report
form build_fieldcatalog.
* There are a number of ways to create a fieldcat.
* For the purpose of this example i will build the fieldcatalog manualy
* by populating the internal table fields individually and then
* appending the rows. This method can be the most time consuming but can
* also allow you more control of the final product.
* Beware though, you need to ensure that all fields required are
* populated. When using some of functionality available via ALV, such as
* total. You may need to provide more information than if you were
* simply displaying the result
* I.e. Field type may be required in-order for
* the 'TOTAL' function to work.
fieldcatalog-fieldname = 'EBELN'.
fieldcatalog-seltext_m = 'Purchase Order'.
fieldcatalog-col_pos = 0.
fieldcatalog-outputlen = 10.
fieldcatalog-emphasize = 'X'.
fieldcatalog-key = 'X'.
* fieldcatalog-do_sum = 'X'.
* fieldcatalog-no_zero = 'X'.
append fieldcatalog to fieldcatalog.
clear fieldcatalog.
fieldcatalog-fieldname = 'EBELP'.
fieldcatalog-seltext_m = 'PO Item'.
fieldcatalog-col_pos = 1.
append fieldcatalog to fieldcatalog.
clear fieldcatalog.
fieldcatalog-fieldname = 'STATU'.
fieldcatalog-seltext_m = 'Status'.
fieldcatalog-col_pos = 2.
append fieldcatalog to fieldcatalog.
clear fieldcatalog.
fieldcatalog-fieldname = 'AEDAT'.
fieldcatalog-seltext_m = 'Item change date'.
fieldcatalog-col_pos = 3.
append fieldcatalog to fieldcatalog.
clear fieldcatalog.
fieldcatalog-fieldname = 'MATNR'.
fieldcatalog-seltext_m = 'Material Number'.
fieldcatalog-col_pos = 4.
append fieldcatalog to fieldcatalog.
clear fieldcatalog.
fieldcatalog-fieldname = 'MENGE'.
fieldcatalog-seltext_m = 'PO quantity'.
fieldcatalog-col_pos = 5.
append fieldcatalog to fieldcatalog.
clear fieldcatalog.
fieldcatalog-fieldname = 'MEINS'.
fieldcatalog-seltext_m = 'Order Unit'.
fieldcatalog-col_pos = 6.
append fieldcatalog to fieldcatalog.
clear fieldcatalog.
fieldcatalog-fieldname = 'NETPR'.
fieldcatalog-seltext_m = 'Net Price'.
fieldcatalog-col_pos = 7.
fieldcatalog-outputlen = 15.
fieldcatalog-do_sum = 'X'. "Display column total
fieldcatalog-datatype = 'CURR'.
append fieldcatalog to fieldcatalog.
clear fieldcatalog.
fieldcatalog-fieldname = 'PEINH'.
fieldcatalog-seltext_m = 'Price Unit'.
fieldcatalog-col_pos = 8.
append fieldcatalog to fieldcatalog.
clear fieldcatalog.
endform. " BUILD_FIELDCATALOG
*& Form BUILD_LAYOUT
* Build layout for ALV grid report
form build_layout.
gd_layout-no_input = 'X'.
gd_layout-colwidth_optimize = 'X'.
gd_layout-totals_text = 'Totals'(201).
* gd_layout-totals_only = 'X'.
* gd_layout-f2code = 'DISP'. "Sets fcode for when double
* "click(press f2)
* gd_layout-zebra = 'X'.
* gd_layout-group_change_edit = 'X'.
* gd_layout-header_text = 'helllllo'.
endform. " BUILD_LAYOUT
*& Form DISPLAY_ALV_REPORT
* Display report using ALV grid
form display_alv_report.
gd_repid = sy-repid.
call function 'REUSE_ALV_GRID_DISPLAY'
exporting
i_callback_program = gd_repid
* i_callback_top_of_page = 'TOP-OF-PAGE' "see FORM
* i_callback_user_command = 'USER_COMMAND'
* i_grid_title = outtext
is_layout = gd_layout
it_fieldcat = fieldcatalog[]
* it_special_groups = gd_tabgroup
* IT_EVENTS = GT_XEVENTS
i_save = 'X'
* is_variant = z_template
tables
t_outtab = it_ekko
exceptions
program_error = 1
others = 2.
if sy-subrc <> 0.
* MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
* WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
endif.
endform. " DISPLAY_ALV_REPORT
*& Form DATA_RETRIEVAL
* Retrieve data form EKPO table and populate itab it_ekko
form data_retrieval.
select ebeln ebelp statu aedat matnr menge meins netpr peinh
up to 10 rows
from ekpo
into table it_ekko.
endform. " DATA_RETRIEVAL