Modifications needed to form events chapter

[weaverryan]

The form events chapter just underwent a big addition and facelift in #1842 and #2417. But, it's still not quite right. Here are the needed changes:

• Simplify the first example - a subscriber is overkill, a listener is easier, and a callback is probably the best approach
• We need to document every form event and its purpose, what its data is, etc
• Both the FriendMessage and SportsMeetup examples aren't really completed. They leave out more detail than I like and so aren't copy-and-pastable. This is especially true of SportsMeetup, where I ran out of steam to keep going :). Ideally, all three examples would be more consistent - building up on the same example, not three different examples.
• I think we need to spend some time on the AJAX experience that's so common when you have one form field that depends on another (i.e. user selects "Country", AJAX request is made to update the "State" field).

[peshi]

@weaverryan +10

http://symfony.com/doc/current/cookbook/form/dynamic_form_modification.html

"One piece that may still be missing is the client-side updating of your form after the sport is selected. This should be handled by making an AJAX call back to your application. In that controller, you can submit your form, but instead of processing it, simply use the submitted form to render the updated fields. The response from the AJAX call can then be used to update the view."

How is this done?

A full example of how to handle the AJAX call to the application/controller and how to use the submitted form to render the updated fields/form would be very usefull.

also "acme.form.meetup_registration_listener" is missing a : at the end.

[tkleinhakisa]

Hi, i just struggled a bit with form events and dynamic fields.

I was adding fields in the SUBMIT event and even if the field was validated the error was not added to the form. Just moving from SUBMIT to PRE_SUBMIT did the trick.

The requirement for PRE_SUBMIT if your field has constraints could be documented

Thank you

[carsonbot]

Thank you for this issue.
There has not been a lot of activity here for a while. Has this been resolved?

[carsonbot]

Friendly ping? Should this still be open? I will close if I don't hear anything.

[wouterj]

For a while already, we have an article dedicated to all events: https://symfony.com/doc/current/form/events.html

That fixes the biggest points in this issue, so let's close here. (updating to more real examples is something that applies to many articles, there is no need for an open issue for that imho)