Create Table Control Using ABAP Programming
In last two weeks, I have learned self-taught how to create table control in SAP Screen using ABAP 4. After trial and error, finally I have finished my small project. While learning about table control, I use SAP Help as main reference, some websites and presentation slides from Michael Adams, Queensland University of Technology.
A Table Control is a screen ‘container’ or object that allows display of multiple rows of a table (database or internal table) on a screen. It is good for displaying a one-to-many relationship on the one screen. The table control object has many features built in to enhance screen display and usability.
Table Control features allow
- horizontal & vertical scrolling
- column width resizing
- scrolling within a field (where contents are wider than the screen field width)
- reordering the sequence of columns
- saving the current display settings for future use
- selection of table rows & columns
Formatting features include
- automatic table resizing on window resize
- separator lines between rows & columns
- column header fields for all columns
Here steps to create table control
1. Declare the table control
As well as drawing the table control on the screen it is necessary to declare the table control as a data item (in the TOP include program for the transaction).
CONTROLS ctrl TYPE TABLEVIEW USING SCREEN scr.
- <ctrl> is the name of the table control on a screen in the ABAP program
- <TABLEVIEW> corresponds to a complex type – (CXTAB_CONTROL defined in the ABAP dictionary)
- <scr> is the screen from which the table control will get its initial values
2. Adding table control to a screen
In the graphical screen editor choose the table control element button. Use the left mouse button to position and size the control on the screen.
Then input the name of table control.
3. Adding Field to a table control
To add field to table control, we can retrieve from table or internal table. Click on icon “dictionary/program field window” or function key F6.
There two option while retrieve field, i.e. based on database table or internal table. If want to retrieve from database table, input the name of table then click push button “Get from Dictionary”. If want to retrieve from internal table, input the internal table name then click push button “Get from program”.
Mark the field to be added to table control, and then click on push button OK.
Drag selected fields into table then release the mouse button.
Here the fields we selected will be displayed in reversed order. I do not exactly why it happens. I have tried some ways and tricks to display in correct order, but the fields still displayed in reversed order. Finally, to get the correct order I selected the fields one by one.
4. Adding label for each column
Label column is text field. To add it, just click on the text field icon, drag it onto header of the column and then type the label.
Table Control Principle
There are a set of programming principles that should be adhered to when using table controls and step loops. Data from the database should be initially loaded into an internal table. This means that the database is accessed for read purposes only once in the transaction. Next the rows of the internal table are loaded into the table control. Any changes that are made to the data are then saved back to the internal table. At the end of the transaction, the contents of the internal table can be written back to the database, again to minimize database I/O.
PAI logic for screen 1 (see screen below) loads the internal table with data from the database according to the entries supplied by the user.
PBO logic for screen 2 (see screen below) populates the table control from the internal table (buffer).
User action in screen 2 triggers the PAI logic. PAI logic updates the internal table with new values entered (into the table control screen fields) by the user.
PAI logic is triggered by actions such as scrolling down a single row as well as actions such as BACK, EXIT, etc.
Unless the user action causes the transaction to leave the current screen, after the PAI modules have been executed, the PBO modules for the screen are executed again. Thus the table control fields are updated or refreshed after every user action.
PBO (Process Before Output)
In PBO processing fields are transported from the module pool to the screen in a predefined order.
- The table control step loop is processed row by row. Fields with corresponding names are transported from the module pool to the screen.
- After the step loop has been processed all remaining module pool fields are transported to the screen.
PAI (Process After Input)
- All screen fields that do not belong to a table control and are not specified in a FIELD statement are transported to module pool fields
- Table control fields are transported row by row to module pool fields
- Fields specified in FIELD statements are transported immediately before the FIELD statement is executed
Updating data in table control
The ABAP language provides two mechanisms for loading the table control with data from the internal table and then storing the altered rows of the table control back to the internal table.
- Method 1: Read the internal table into the Table Control in the screen’s flow logic. Used when the names of the Table Control fields are based on fields of the internal table.
- Method 2: Read the internal table into the Table Control in the module pool code. Used when the names of the Table Control fields are based on fields of the database table.
Method 1 (table control fields = itab fields)
In the flow logic we can read an internal table using the LOOP statement. Define the reference to the relevant able control by specifying WITH CONTROL <ctrl>
Determine which table entry is to be read by specifying CURSOR <ctrl>-CURRENT_LINE.
After the read operation the field contents are placed in the header line of the internal table. If the fields in the table control have the same name as the internal they will be filled automatically. Otherwise we need to write a module to transfer the internal table fields to the screen fields.
We must reflect any changes the user makes to the fields of the table control in the internal table otherwise they will not appear when the screen is redisplayed after PBO processing, (eg, after the user presses Enter or scrolls) However, this processing should be performed only if changes have actually been made to the screen fields of the table control (hence the use of the ON REQUEST)
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PROCESS BEFORE OUTPUT. LOOP AT ITAB_REG WITH CONTROL TCREG CURSOR TCREG-CURRENT_LINE. ENDLOOP. PROCESS AFTER INPUT. LOOP AT ITAB_REG. MODULE MODIFY_ITAB_REG. ENDLOOP. MODULE MODIFY_ITAB_REG INPUT. MODIFY ITAB_REG INDEX TCREG-CURRENT_LINE. ENDMODULE.
Method 2 (table control fields = dict. fields)
If using a LOOP statement without an internal table in the flow logic, we must read the data in a PBO module which is called each time the loop is processed.
Since, in this case, the system cannot determine the number of internal table entries itself, we must use the EXIT FROM STEP-LOOP statement to ensure that no blank lines are displayed in the table control if there are no more corresponding entries in the internal table.
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PROCESS BEFORE OUTPUT. LOOP WITH CONTROL TCREG. MODULE READ_ITAB_REG. ENDLOOP. PROCESS AFTER INPUT. LOOP WITH CONTROL TCREG. CHAIN. FIELD: ITAB_REG-REG, ITAB_REG-DESC. MODULE MODIFY_ITAB_REG ON CHAIN-REQUEST. ENDCHAIN. ENDLOOP. MODULE READ_ITAB_REG OUTPUT. READ TABLE ITAB_REG INDEX TCREG-CURRENT_LINE. I IF SY-SUBRC EQ 0. MOVE-CORRESPONDING ITAB_REREG TO TCREG. ELSE. EXIT FROM STEP-LOOP. ENDIF. ENDMODULE. MODULE MODIFY_ITAB_REG INPUT. MOVE-CORRESPONDING TCREG TO ITAB_REG. MODIFY ITAB_REG INDEX TCREG-CURRENT_LINE. ENDMODULE.
Updating the internal table
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PROCESS AFTER INPUT. LOOP AT ITAB_REG. CHAIN. FIELD: ITAB_REG-REG, ITAB_REG-DESC. MODULE MODIFY_ITAB_REG ON CHAIN-REQUEST. ENDCHAIN. ENDLOOP. MODULE MODIFY_ITAB_REG INPUT. ITAB_REG-MARK = 'X'. MODIFY ITAB_REG INDEX TCREG-CURRENT_LINE. ENDMODULE.
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PROCESS AFTER INPUT. LOOP WITH CONTROL TCREG. CHAIN. FIELD: TCREG-REG, TCREG-DESC. MODULE MODIFY_ITAB_REG ON CHAIN-REQUEST. ENDCHAIN. ENDLOOP. MODULE MODIFY_ITAB_REG INPUT. MOVE-CORRESPONDING TCREG TO ITAB_REG. I TAB_REG-MARK = 'X'. MODIFY ITAB_REG INDEX TCREG-CURRENT_LINE. ENDMODULE.
Updating the database
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MODULE USER_COMMAND_100. CASE OK_CODE. WHEN ‘SAVE’. LOOP AT ITAB-REG. CHECK ITAB_REG-MARK = ‘X’. MOVE-CORRESPONDING ITAB_REG TO TCREG. UPDATE TCREG. ENDLOOP. WHEN ... ... ENDCASE. ENDMODULE.
Those are the simple steps how to create table control. What I have learned this week only the beginning. Actually there are more areas in SAP Table Control with abap programming that can be explored deeper, but may be next time.
Filed under: Abap/4
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