IBM i RPGLE replacing ERRMSGID with Message Subfile

Hey there, RPG programmers! Today's post tackles a common scenario: enforcing a required field in an RPG program using free format. We'll ditch the hardcoded error indicators and embrace the power of snd-msg for a cleaner, more flexible approach.

The Challenge:

Imagine you need to mark a field as mandatory in an existing RPG program. You dig into the code, only to find a maze of cryptic error indicators triggering messages on the display file. Yikes! Hunting down an unused indicator feels like a treasure hunt with uncertain rewards.

The Solution: Embrace snd-msg!

There's a better way! We'll leverage the snd-msg command to display clear, user-friendly error messages. Here's the breakdown:

1. Message Subfile: First, add a message subfile to your display file. This subfile will house the custom error messages you'll display later.

2. Code Modification: Now, let's dive into the program code. We'll strategically add logic to:

   • Write the message control subfile (pointing to the appropriate message in your new subfile).
   • Clear any existing messages after the exfmt command (ensuring only the new message is displayed).

3. snd-msg Replaces Indicators: Find those hardcoded indicator assignments you encountered earlier. Replace them with the snd-msg command, referencing the message control subfile you just created.

A Targeted Approach:

Remember, we don't need to overhaul the entire program at once. If you have multiple screens with text in line 24 (a common spot for error messages), focus on modifying the specific screens where you need to enforce required fields.

External Message Subfile - A Bonus Tip:

While using an external message subfile is my preferred approach, the function to send text from the program offers a handy alternative for quick fixes.

Modernizing Your Code:

The code I encountered was in the old-school RG4 format. Don't fret! Utilize the JCRCMDS command to convert it to full RPG4 syntax. This ensures your code is up-to-date and leverages the latest RPG features. Finally, I used RPGTOOLBOX to convert to free format for improved readability and maintainability.

Wrapping Up:

By embracing snd-msg and external message subfiles, you can create a more flexible and user-friendly experience for your RPG programs. Remember, targeted modifications and modernizing your codebase go a long way in keeping your RPG applications clean and efficient. Happy coding!