验证Drupal表单中的输入

Question

I have a Drupal form wherein someone inputs information, and I need to do a database query to check if it is valid before submitting. I would like to either have a button the user can click to check the validity (or have it be done automatically after the user leaves that field), and then display some information about his selection.
I know I can use hook_form_submit to review a form when it is submitted and then stop the process if there are any errors, but I would like the user to be able to confirm they have selected the correct thing before submitting the form.

Answer 1

I haven't personally tried this module, but it might be what you're looking for:

http://drupal.org/project/ajax

If you're just looking for a way to do real-time lookups (e.g. entering the book barcode and getting the title), you can also use Drupal's autocomplete feature, but it will require you to write your own autocomplete function to handle the database lookups.