Create Dynamic Table using RTTS and display in ALV

This document stems from the document Dynamic Internal Table iIlustrated with an example of creating the transpose of internal table which explains use of field symbols, data references and creating a dynamic internal table as a transpose of an internal table using cl_alv_table_create=>create_dynamic_table.

Exploring into the much recommended RTTS method, I have found that not only is it more powerful but that it is more simpler than the old method. I will be using the same example as mentioned in the previous document to explain the use of RTTS.

As already mentioned, creation and population of dynamic internal table can be done in three steps.

1. Creating structure
2. Creating dynamic internal table from this structure.
3. Populating the table.

While using the old technique (cl_alv_table_create=>create_dynamic_table,), the first step was fulfilled by creating a field catalog  and the second step using the above mentioned method call.

When creating dynamic table using RTTS, the first and second steps can be done using the methods provided by RTTS.

Before going into the details, I shall brief you very shortly on RTTS and its methods.

In ABAP Objects, there is a class-based concept called Run Time Type Information (RTTI) that you can use to determine type attributes at run time. The methods used in this class replaces statements like describe table, describe field etc.

Another concept Run time Type Creation (RTTC) was added to the above to create data of any type dynamically.

Both these together comprise the RTTS (Run time Type Services).

The RTTS contains a hierarchy of classes having attributes and methods that are used to perform these dynamic functions, which could be to get the attributes of a data object at run time or to create a data object dynamically.

Lets see our scenario again.

We have an internal table IT_DEMO containing three columns – vendor name (vend), Month(month), Amount Due(amt).

TYPES : BEGIN OF gfirst_typ,
vend(6)  TYPE c,
month(5) TYPE c,
amt      TYPE  i.
TYPES : END OF gfirst_typ.

* Input table declarations
DATA :     it_zdemo TYPE TABLE OF gfirst_typ,
wa_zdemo LIKE LINE OF it_zdemo.

We need to create something like a transpose for this table dynamically. The output should look like this.

Step 1 – Create Structure.

The RTTI contains attributes and methods that are used in this hierarchy of classes to get the property of variables whether it is a field or structure or table or an object instance of a class, at run time.

All these methods and attributes belong to the super class cl_abap_typedescr.

For our purpose, we shall be using the method describe_by_data to get the data type attribute of a field in the input table.

We shall be calling this method from the class cl_abap_datadescr, since the destination variable is an object type ref to cl_abap_datadescr. As we are calling the method of parent class from inherited class, we should use the casting operator ‘?=’ , rather than the simple assignment operator ‘=’, to avoid any type cast error.

ls_component-type ?= cl_abap_datadescr=>describe_by_data( wa_zdemo-vend ).

Here the data type attributes of the field wa_zdemo-vend which is declared as a six character variable will be passed to ls_component-type which is data reference pointing to an object of type cl_abap_datadescr. This is the first column of the dynamic table.

DATA :

ls_component    TYPE cl_abap_structdescr=>component,

gt_component    TYPE cl_abap_structdescr=>component_table.

ls_component-name = ‘VEND’.
ls_component-type ?= cl_abap_datadescr=>describe_by_data( wa_zdemo-vend ).
APPEND ls_component TO gt_component.

The rest of the columns are fields Jan, Feb containing the amount for that month depending on the data of the input table. (Refer the input table example shown above to understand better)

*Loop through the internal table creating a column for every distinct month in the internal table
LOOP AT it_zdemo INTO wa_zdemo.
* Search the component table if the month column already exists.
READ TABLE gt_component INTO ls_component WITH KEY name = wa_zdemo-month.
IF sy-subrc NE 0.
* The name of the column would be the month and the data type would be same as the amount field of internal table.    
ls_component-name = wa_zdemo-month.
ls_component-type ?= cl_abap_datadescr=>describe_by_data( wa_zdemo-amt ).
APPEND ls_component TO gt_component.
ENDIF.
CLEAR : ls_component, wa_zdemo.
ENDLOOP.

Now we have the components of the structure and the table. To create the structure we shall be using the method in RTTC.

Methods in RTTC were added to the RTTS type classes to facilitate the creation of types at runtime.

To create the structure, we shall be using the static method create() in the class cl_abap_structdescr.

DATA :   gr_struct_typ   TYPE REF TO  cl_abap_datadescr.

gr_struct_typ  ?= cl_abap_structdescr=>create( p_components = gt_component ).

Step 2 – Create Table.

To create a table, first we create the table type from the structure created above. For this, we use the static method create() of the cl_abap_tabledescr.

DATA :   gr_dyntable_typ TYPE REF TO  cl_abap_tabledescr.

gr_dyntable_typ = cl_abap_tabledescr=>create( p_line_type = gr_struct_typ ).

Once the table type is created, we instantiate a reference variable to point to data object of this table type.

** Dynamic Table Declarations
DATA :  gt_dyn_table     TYPE REF TO data,
gw_dyn_line      TYPE REF TO data,

CREATE DATA gt_dyn_table TYPE HANDLE gr_dyntable_typ.

Similarly a reference variable of the structure is also created from the structure created as a work area of the table.

CREATE DATA  gw_dyn_line TYPE HANDLE gr_struct_typ.

Step 3 – Populate internal table.

Now our dynamic table is alive and we just need to populate the data. This is done the same way it was done in the earlier document Dynamic Internal Table iIlustrated with an example of creating the transpose of internal table. You access each cell of the table using field symbols. Refer the above document for more information on field symbols and data references.

Populate the dynamic table
LOOP AT it_zdemo INTO wa_zdemo.
* Avoid duplicate entries for key field Vendor.
READ TABLE <gfs_dyn_table> INTO <gfs_line1> WITH KEY (‘VEND’) = wa_zdemo-vend.
IF sy-subrc = 0.
*if <gfs_line1> is ASSIGNED.
*  UNASSIGN <gfs_line1>.
CONTINUE.
ENDIF.

ASSIGN COMPONENT ‘VEND’ OF STRUCTURE <gfs_line> TO <fs1>.
*if <fs1> is ASSIGNED.
<fs1> = wa_zdemo-vend.
UNASSIGN <fs1>.
**endif.

LOOP AT gt_component INTO ls_component.
IF ls_component-name = ‘VEND’.
CONTINUE.
ENDIF.
READ TABLE it_zdemo WITH KEY vend = wa_zdemo-vend month = ls_component-name INTO wa_zdemo1.
IF sy-subrc = 0.
ASSIGN COMPONENT ls_component-name OF STRUCTURE <gfs_line> TO <fs1>.
IF <fs1> IS ASSIGNED.
<fs1> = wa_zdemo1-amt.
UNASSIGN <fs1>.
ENDIF.
ENDIF.
CLEAR : wa_zdemo1.
ENDLOOP.
APPEND <gfs_line> TO <gfs_dyn_table>.
CLEAR: <gfs_line>.
CLEAR: wa_zdemo, wa_zdemo1.
ENDLOOP.

Display the contents of dynamic table in ALV

The contents of the dynamic internal table can be displayed using the factory method in cl_salv_table.

TRY.
cl_salv_table=>factory(
IMPORTING
r_salv_table   = lo_salv_table
CHANGING
t_table        = <gfs_dyn_table>
).
CATCH cx_salv_msg .
ENDTRY.

lo_salv_table->display( ).

Complete Code

*&———————————————————————*
*& Report  ZDYNAMIC_TABLE
*&———————————————————————*

REPORT  zdynamic_table_rtts.
*Author : Susmitha Susan Thomas

TYPE-POOLS : slis.
TYPES : BEGIN OF gfirst_typ,
vend(6)  TYPE c,
month(5) TYPE c,
amt      TYPE  i.
TYPES : END OF gfirst_typ.

* Input table declarations
DATA :     it_zdemo TYPE TABLE OF gfirst_typ,
wa_zdemo LIKE LINE OF it_zdemo,
wa_zdemo1 LIKE LINE OF it_zdemo.

** Dynamic Table Declarations
DATA :  gt_dyn_table     TYPE REF TO data,
gw_dyn_line      TYPE REF TO data,
gw_dyn_line1     TYPE REF TO data.

* Field Symbold Declaration
FIELD-SYMBOLS: <gfs_line>,<gfs_line1>,
<gfs_dyn_table> TYPE STANDARD TABLE,
<fs1>.

* RTTS Declaratoins.
DATA :   gr_struct_typ   TYPE REF TO  cl_abap_datadescr,
gr_dyntable_typ TYPE REF TO  cl_abap_tabledescr,
ls_component    TYPE cl_abap_structdescr=>component,
gt_component    TYPE         cl_abap_structdescr=>component_table.

* SALV Declarations.
DATA  : lo_cols TYPE REF TO cl_salv_columns,
lo_salv_table          TYPE REF TO cl_salv_table,
lo_column TYPE REF TO cl_salv_column,
col_name(30),
col_desc(20).

*START-OF-SELECTION.
* Populate the initial input table. Usually this input table contents will be populated at run time, which raises the requirement of dynamic table. The table contents are filled here for illustration purpose.
perform fill_table using :
‘V100’ ‘JAN’ ‘100’,
‘V100’ ‘FEB’ ‘250’,
‘V200’ ‘FEB’ ‘200’,
‘V300’ ‘FEB’ ‘150’,
‘V200’ ‘MAR’ ‘250’,
‘V300’ ‘MAR’ ‘300’,
‘V100’ ‘APR’ ‘200’,
‘V100’ ‘MAY’ ‘100’,
‘V200’ ‘MAY’ ’50’,
‘V300’ ‘MAY’ ‘125’,
‘V400’ ‘MAY’ ‘475’.

WRITE : / ‘Initial Internal Table’, /.
WRITE :/(6) ‘Vendor’,(12) ‘Month’ ,  (3) ‘Amt’ .
LOOP AT it_zdemo INTO wa_zdemo.
WRITE :/ wa_zdemo-vend, wa_zdemo-month, wa_zdemo-amt.
ENDLOOP.

* Create structure of dynamic internal table – Vendor Jan13 Feb13 Mar13 ….
ls_component-name = ‘VEND’.
ls_component-type ?= cl_abap_datadescr=>describe_by_data( wa_zdemo-vend ).
APPEND ls_component TO gt_component.

*Loop through the internal table creating a column for every distinct month in the internal table
LOOP AT it_zdemo INTO wa_zdemo.
* Search the component table if the month column already exists.
READ TABLE gt_component INTO ls_component WITH KEY name = wa_zdemo-month.
IF sy-subrc NE 0.
* The name of the column would be the month and the data type would be same as the amount field of internal table.
ls_component-name = wa_zdemo-month.
ls_component-type ?= cl_abap_datadescr=>describe_by_data( wa_zdemo-amt ).
APPEND ls_component TO gt_component.
ENDIF.
CLEAR : ls_component, wa_zdemo.
ENDLOOP.

gr_struct_typ  ?= cl_abap_structdescr=>create( p_components = gt_component ).
gr_dyntable_typ = cl_abap_tabledescr=>create( p_line_type = gr_struct_typ ).

CREATE DATA:
gt_dyn_table TYPE HANDLE gr_dyntable_typ,
gw_dyn_line TYPE HANDLE gr_struct_typ,
gw_dyn_line1 TYPE HANDLE gr_struct_typ.

ASSIGN gt_dyn_table->* TO <gfs_dyn_table>.
ASSIGN gw_dyn_line->* TO <gfs_line>.
ASSIGN gw_dyn_line1->* TO <gfs_line1>.
*
** Populate the dynamic table

*
LOOP AT it_zdemo INTO wa_zdemo.

* Avoid duplicate entries for key field Vendor.
READ TABLE <gfs_dyn_table> INTO <gfs_line1> WITH KEY (‘VEND’) = wa_zdemo-vend.
IF sy-subrc = 0.
*if <gfs_line1> is ASSIGNED.
*  UNASSIGN <gfs_line1>.
CONTINUE.
ENDIF.

ASSIGN COMPONENT ‘VEND’ OF STRUCTURE <gfs_line> TO <fs1>.
*if <fs1> is ASSIGNED.
<fs1> = wa_zdemo-vend.
UNASSIGN <fs1>.
**endif.

LOOP AT gt_component INTO ls_component.
IF ls_component-name = ‘VEND’.
CONTINUE.
ENDIF.
READ TABLE it_zdemo WITH KEY vend = wa_zdemo-vend month = ls_component-name INTO wa_zdemo1.
IF sy-subrc = 0.
ASSIGN COMPONENT ls_component-name OF STRUCTURE <gfs_line> TO <fs1>.
IF <fs1> IS ASSIGNED.
<fs1> = wa_zdemo1-amt.
UNASSIGN <fs1>.
ENDIF.
ENDIF.
CLEAR : wa_zdemo1.
ENDLOOP.
APPEND <gfs_line> TO <gfs_dyn_table>.
CLEAR: <gfs_line>.
CLEAR: wa_zdemo, wa_zdemo1.
ENDLOOP.

TRY.
cl_salv_table=>factory(
IMPORTING
r_salv_table   = lo_salv_table
CHANGING
t_table        = <gfs_dyn_table>
).
CATCH cx_salv_msg .
ENDTRY.

* get columns object
lo_cols = lo_salv_table->get_columns( ).

*…Individual Column Names
LOOP AT gt_component INTO ls_component.
TRY.
col_name = ls_component-name.
lo_column = lo_cols->get_column( col_name ). ” < <
IF col_name = ‘VEND’.
col_desc = ‘Vendor’.
ELSE.
CONCATENATE col_name ”’13’ INTO col_desc.
ENDIF.
lo_column->set_medium_text( col_desc ).
lo_column->set_output_length( 10 ).
CATCH cx_salv_not_found.                            “#EC NO_HANDLER
ENDTRY.
ENDLOOP.
* display table

lo_salv_table->display( ).

FORM fill_table
USING p_fld1 TYPE gfirst_typ-vend
p_fld2 TYPE gfirst_typ-month
p_fld3 TYPE gfirst_typ-amt.

clear wa_zdemo.
wa_zdemo-vend = p_fld1 .
wa_zdemo-month = p_fld2.
wa_zdemo-amt = p_fld3.
APPEND wa_zdemo TO it_zdemo.

ENDFORM.                    “FILL_TABLE

Output

Acknowledgements

The figures of RTTS class hierarchy were taken from the TAW study material.