# Observe\_field and :on

**URL:** <https://www.ruby-forum.com/t/observe-field-and-on/171311>\
**Category:** Rails\
**Created:** [June 30, 2009, 2:05pm UTC](https://www.ruby-forum.com/t/observe-field-and-on/171311 "2009-06-30T14:05:35Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![snusmu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/8797f3/32.png) [@snusmu](https://www.ruby-forum.com/u/snusmu)\
**Post date:** [June 30, 2009, 2:05pm UTC](https://www.ruby-forum.com/t/observe-field-and-on/171311/1 "2009-06-30T14:05:35Z")

</div>

Hi all,

for some reason when i am using :on =\> “keyup”(or any other value)  
parameter for observe\_field, it doesn’t work at all. This code:

\<%= text\_field\_tag :search\_for\_user,"" %\>  
\<%= observe\_field :search\_for\_user, :on =\> “keyup”, :url =\> {  
:controller =\> ‘user’, :action =\> :ajax\_find\_for\_group}, :update =\>  
:suggest\_user, :with =\> “‘search\_value=’+value” %\>

gives:

//\<![CDATA[new Form.Element.EventObserver('search\_for\_user', function(element, value) {new Ajax.Updater('suggest\_user', '/user/ajax\_find\_for\_group', {asynchronous:true, evalScripts:true, parameters:'search\_value='+value})}) //]]\> \</script\> \<p\>I know that there is no :on parameters for observe\_field in\<br\> documentation, but i notice some people using it with success on forums.\<br\> Is there some kind of patch or something? Help!\</p\> \<p\>rails 2.3.2, ruby 1.8.7\</p\>

---

<div class="post-metadata">

**Author:** ![snusmu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/8797f3/32.png) [@snusmu](https://www.ruby-forum.com/u/snusmu)\
**Post date:** [July 2, 2009, 6:07pm UTC](https://www.ruby-forum.com/t/observe-field-and-on/171311/2 "2009-07-02T18:07:14Z")

</div>

ok, i found out that there is no :on parameter for observe\_field  
i noticed that it’s not in documentation but found some examples where  
people use it. i suppose they have some patched or older version of  
rails where this was supported.

so, seems it’s not possible to use “onkeydown” property of text field  
with observe\_field without patches.

installed autocomplete plugin instead

thanks for help everybody!)