Ask HN: What is the best way to verify forms

To be honest, I hate GUI programming. You always have to verify the data a user enters and convert this data into your data structures. You could do it the easy way and just make the GUI elements reflect the schema of your data structure, but often this approach is not very user-friendly.

E.g. it's easier for the user to enter a list of IP addresses separated by commas, but your data structure holds an array of IP addresses. If the user enters invalid data, this must be shown in the GUI as an error.

And anytime the user modifies something, the data structures have to be modified (or not, depending on whether you decide to save automatically or have a 'save' button) and certain parts of your GUI have to be updated, too.

Usually when I start writing something like this, it becomes incredibly complex code.

What is the best concept to handle serialize and de-serialize user input in a GUI? Any good videos of talks about this?

I am not looking for a specific library in JS, C++ or what ever, but rather for a concept/programming pattern/whatever to deal with this situation.