Hi GetRXd,
You can use the Conditional Warning action to do this.
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Here, the Conditional Warning action is checking if the value in the Opportunity Name field is empty (more specifically, "equal to <blank>"). If it is empty, the specified Warning Message will be displayed to the user and no more actions will get processed (in other words, the record will not be saved - this forces the user to enter something here).
You can set up a Conditional Warning action the same way, to check if data has been entered for any field on screen. Conveniently, the other Save buttons on this screen (Save & New, etc) are set up to reference this Save button, so you'll only have to add your actions here to affect all of them.
If you would like to hire a member of our Professional Services team to do some customization for you, let me know and I'll have your account manager reach out to discuss the specifics.
- Justin