How to display validation after the form has been generated via Ajax

Question

I'm struggling to find the best way to display validation messages after a form which has been generated via ajax is submitted. Let me explain better: I've got a page that starts with a few options. Based on what the user selects from dropdowns and by adding new fields, the form is created and at the end the form is submitted.

The problem is that, even if I can do validation checks on the server, and display a general validation message on the page, I should pre-fill the form fields with the values that the user entered before pushing the submit button.

Have you ever had such a problem? How did you address this?

Answer 1

There's a couple ways I could see handling this.

1) Do another AJAX call upon submission that does the validations and returns w/o a full post. It's not an elegant solution since it involves two round trips and depending on the validations would lead to performance issues.

2) When you return the json that is used for extending the form, have it instead turn 2 sets of json objects. The first set of objects would represent the data you're currently using. The second set in the array would represent the validation logic which you can then apply however you need upon the form's creation.

Neither way is truly elegant; however, the latter provides a way minimize round trips to do the validation.

Answer 2

Three options:

1. normal POST -> the server render the form AS it was submitted (you should be able to rebuild the form server side)

2. ajax POST -> just redirect the user if validation succeeded

3. check before post -> synchronous ajax validation calls