Selection Screen Events

Selection Screen Events

• INITIALIZATION.

1. Executes a processing block before the selection screen is processed.
2. In this block you initialize the selection screen.
3. This is also the only possibility to change the default values of parameters or selection criteria defined in logical databases. 
4. . You can find out the names of the internal fields you want to change either by examining the logical database SAPDB<ldb> itself (with the transaction SLDB or by choosing Tools->ABAP/4 Development Workbench->Development->Programming environ.->Logical databases), or by retrieving the technical information of that field.

• AT SELECTION-SCREEN.

1. Executes a processing block after the system has finished processing the selection screen. 
2. If an error|warning message is sent from this processing block, the system displays the selection screen again and all input fields can be changed. 

• AT SELECTION-SCREEN ON .

1.  Syntax : AT SELECTION-SCREEN ON <parm>|<selopt>.
2. Executes a processing block after the system has finished processing the <parm>|<selopt>. 
3. If an error|warning message is sent from this processing block, the system displays the selection screen again and only this input field can be changed. 

• AT SELECTION-SCREEN ON END OF

1. Syntax : AT SELECTION-SCREEN ON END OF <selopt>.
2. Executes a processing block at the end of processing Multiple Selection Window of the <selopt>. Can be used to check the entries in the internal table <selopt>. Both the E and W messages are sent in dialog window.

• AT SELECTION-SCREEN ON BLOCK

1. Syntax : AT SELECTION-SCREEN ON BLOCK <block>. 
2. Executes a processing block after the system has finished processing the <block>. If an error|warning message is sent from this processing block, the system displays the selection screen again and only the input fields in the <block> can be changed. 

•  AT SELECTION-SCREEN ON RADIOBUTTON GROUP

1. Syntax : AT SELECTION-SCREEN ON RADIOBUTTON GROUP <radi>. 
2. Executes a processing block after the system has finished processing the <radi>. If an error|warning message is sent from this processing block, the system displays the selection screen again and only the radiobutton group <radi> can be changed.

• AT SELECTION-SCREEN ON VALUE-REQUEST FOR .

1. Syntax : AT SELECTION-SCREEN ON VALUE-REQUEST FOR <parm>|<selopt>.
2. The possible entries button  automatically appears next to the input field for <parm>|<selopt> when it is selected on the selection screen.
3. Executes a processing block which allows user to choice a value from a list when user presses the button or F4. Can be used only in report programs, not in a logical database program.

• AT SELECTION-SCREEN ON HELP-REQUEST FOR 

1. Syntax :AT SELECTION-SCREEN ON HELP-REQUEST FOR <parm>|<selopt>.
2. Executes a processing block which displays a help text when user presses F1 or the button on the selected <parm>|<selopt>. Can be used only in report programs, not in a logical database program. 

• AT SELECTION-SCREEN OUTPUT.

1. Syntax : 
   AT SELECTION-SCREEN OUTPUT.
2. Executes a processing block during the PBO of a selection screen for each ENTER. For example, here can be applied a modifications to the screen: 
   
   
        LOOP AT SCREEN.
       ....
           MODIFY SCREEN.
         ENDLOOP. 
3. To change at runtime attributes of screen fields. SCREEN is memory table which automatically created and maintained by system (with header line). The structure of the SCREEN:

• To activate a field attribute, set its value to 1. To deactivate it, set it to 0. If ACTIVE = 0, then system sets INVISIBLE = 1 and INPUT = 0, and user can neither see the field nor enter values into it.