What is the difference between CHAIN … ENDCHAIN and FIELD commands in Module Pool?

Answer Posted / dtarunkmr

When You specify FIELD the module you specify is only processed for the field specified in the FIELD statement.If an error or warning message occurs during the module, the system sends the screen again, but
without processing the PBO module . The message is displayed, and only the field to which the check
was applied is ready for input.It is the FIELD statement that is responsible for making the field ready for input again. If you
use a message in a module that is not called from within a FIELD statement, the system displays the
message, but does not make the field ready for input again.


If you want to ensure that more than one field is ready for input following an error dialog, you must
list all of the relevant fields in the FIELD statement, and include both that and the MODULE
statement in a CHAIN … ENDCHAIN block.
n You can include individual fields in more than one CHAIN … ENDCHAIN block.

Many times if the user enters wrong value for one field, then you might want to give option to user to enter all the fields, which is not possible by using Field statement only. This functionality can be achieved by CHAIN – ENDCHAIN.

Syntax

Chain.
Field sflight-carrid value (‘LH’).
Field sflight-connid values (between ‘200’ and ‘500’).
Endchain.

Best Regards,
DTK

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