# Dynamic show form fields depending on dropdown box

**URL:** <https://www.ruby-forum.com/t/dynamic-show-form-fields-depending-on-dropdown-box/107755>\
**Category:** Rails\
**Created:** [June 25, 2007, 11:41pm UTC](https://www.ruby-forum.com/t/dynamic-show-form-fields-depending-on-dropdown-box/107755 "2007-06-25T23:41:06Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![new\_railsor](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/f05b48/32.png) [@new\_railsor](https://www.ruby-forum.com/u/new_railsor)\
**Post date:** [June 25, 2007, 11:41pm UTC](https://www.ruby-forum.com/t/dynamic-show-form-fields-depending-on-dropdown-box/107755/1 "2007-06-25T23:41:06Z")

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I have one question, let me take an example. when a user visits:

[http://www.ruby-forum.com/topic/new?forum\_id=3](http://www.ruby-forum.com/topic/new?forum_id=3)

it will show a form that has forum, name, email, subject, text five  
fields for posting. right?

I want to provide more features on this form page, when the user choose  
a different forum from the first drop list, the form will show more  
different fields, such as a time selecor, or an option or what ever I  
want to show to my users.

how can I do use ruby/rails or javascript? thanks in advance.