RE: Subfile Processing -- RPG400-L

Hi Marvin,

<snip>

So I guess you have to read the subfile record in order for the subfile tobe displayed at the proper position. Go figure.

</snip>

This isn't true.

There are three fields that you use to successfully maintain position withina subfile:1) The relative record number. This field is used to hold your CURRENTposition within the subfile. It is incremented by you during your subfilebuild, and updated by the system whenever you access a subfile record.[defined using the sfile(format : SFLRRN) keyword within your program]. Weshall call this field SFLRRN.2) The subfile record number. This field contains the subfile record youwant to the system to display the next time the subfile is written to thescreen. By populating this you are telling the system to display the pagewhich contains the subfile record with a SFLRRN equal to this value. [defined using the SFLRCDNBR keyword within your DDS]. We shall call thisfield SFLPOS.3) The Subfile Top record number. This field contains the RRN of the topsubfile record on the currently displayed page. [ defined within the INFDSof the display file in positions 378 -379] We shall call this field SFLTOP.(if you disply multiple subfiles this values is not useful and you need touse SFLCSRRRN).

When you build your subfile you increment SFLRRN prior to each write -ensuring a unique value for each record.When you display your subfile for the first time you set SFLPOS to 1. Thisensures you display the first page (as it contains the first subfilerecord).Immediately after the EXFMT you save SFLTOP into SFLPOS. This ensures thatyou will stay on the same page. You're telling the system to position to thepage which contains the subfile record at the top of your current page.Thus, you don't move!If you allow the users to enter data into multiple subfile records accrossmany pages then you can position to erroneous entries as you validate -simply put the RRN of the record you're validating into SFLPOS and redisplaythe screen. Voila! you're positioned to the page which contains the error.If the user fixes the error and presses Enter then they'll either move tothe next error or stay on the same page.


All you need to do is:
1) Set SFLRRN = 0.
2) Build your subfile.

3) At this point SFLRRN = number of subfile records, you should set SFLPOS =1, SFLTOP is set by the system and is currently undefined.4) EXFMT - the page containing SFLRRN = SFLPOS = 1 is displayed - the firstpage.5) Immediately after the EXFMT place SFLTOP into SFLPOS (this ensures youdefault to staying on the current page)

6) Do something exciting in your code...

i) If you want to position to (and display) an invalid subfile line whichyou're working on put SFLRRN into SFLPOS and redisplay.ii) If you want to osition to (and display) any subfile record - readthrough the subfile, select the record based on your search/positioningcriteria, and place SFLRRN into SFLPOS.iii) If you want to simply maintain position then do nothing - you alwaysdefault to this by putting SFLTOP into SFLPOS after the EXFMT.

Basically, if you want to position to ANYWHERE within your subfile simplyplace the RRN of the record you want into SFLPOS. The special case is whenyou want to stay where you are - here you use SFLTOP.

That's it. I've never had any subfile positioning issues using this - and Iuse SFLFOLD/SFLDROP on most screens.

Note: to maintain position within the subfile using SFLTOP and SFLPOS Ididn't need to chain to ANY subfile records - I simply used the two fieldsthe system provides for this purpose.

Finally, NEVER use the same field for your relative record number (SFLRRN)and your subfile record number (SFLPOS) as this will only lead to confusionand the need for extra save variables to "hold the current subfile size" orto "hold your current position", etc..


HTH

Larry Ducie