I am trying to get an understanding of Validation in regards to Nintex Forms and Workflows.
Having worked as an ASP/ASPX Developer, it has always been stated that Server-side Validation is the Golden Rule. Client-side Validation is convenient but should be backed up with Server-side Routines.
Client-side Validation is subject to browser manipulation and hijacking.
What are community thoughts on this issue?
I agree that server side validation is best and tend to add validation from the column configuration where possible, but unfortunately we are somewhat bound to SP constraints so where I absolutely have to I use client side validation with Nintex. I'm a bit on the fence as to how I feel about the risk, if you're running on prem internal only then it's relatively low risk, but SP Online or an extranet on prem definitely seems like risky business to me.
We are running on prem. I guess one thing to consider are restraints on the lists and libraries themselves. If some validation were hijacked, SharePoint would probably cause an error condition. For example if a required field was not filled in.