# Related drop down list / ajax

**URL:** <https://www.ruby-forum.com/t/related-drop-down-list-ajax/52411>\
**Category:** Rails\
**Created:** [January 13, 2006, 8:19pm UTC](https://www.ruby-forum.com/t/related-drop-down-list-ajax/52411 "2006-01-13T20:19:23Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Harm\_de\_Laat](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/9de053/32.png) [@Harm\_de\_Laat](https://www.ruby-forum.com/u/Harm_de_Laat)\
**Post date:** [January 13, 2006, 8:19pm UTC](https://www.ruby-forum.com/t/related-drop-down-list-ajax/52411/1 "2006-01-13T20:19:23Z")

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Hi all,

I’m trying to create a related dropdown box:

In my view:

 Select category \<% @categories.each do |category| %\> \<%= category.title %\> \<% end %\> No Brand \<% for brand in @brands -%\> \<%= brand.title %\> \<% end -%\>

\<%= observe\_field(“category”,  
:frequency =\> 0.25,  
:update =\> “brand\_id\_container”,  
:url =\> { :action =\> :get\_brands\_for\_category },  
:with =\> “‘category\_id=’+value”) %\>

In my controller:

def get\_brands\_for\_category  
@brands = Brand.find\_all\_by\_category\_id(@params[“category\_id”])  
end

Somehow it does not work. The related dropdown list does not change  
contents. Does anybody have an idea why?

Regards,

Harm de Laat

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<div class="post-metadata">

**Author:** ![Harm\_de\_Laat](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/9de053/32.png) [@Harm\_de\_Laat](https://www.ruby-forum.com/u/Harm_de_Laat)\
**Post date:** [January 14, 2006, 11:37am UTC](https://www.ruby-forum.com/t/related-drop-down-list-ajax/52411/2 "2006-01-14T11:37:19Z")

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Anybody?

---

<div class="post-metadata">

**Author:** ![Harm\_de\_Laat](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/9de053/32.png) [@Harm\_de\_Laat](https://www.ruby-forum.com/u/Harm_de_Laat)\
**Post date:** [January 15, 2006, 5:32am UTC](https://www.ruby-forum.com/t/related-drop-down-list-ajax/52411/3 "2006-01-15T05:32:02Z")

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Try putting the second inside a

  
and  
return the entire select from your action.You would need a render  
partial or  
a render text which spews out HTML  
Vivek

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<div class="post-metadata">

**Author:** ![Harm\_de\_Laat](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/h/9de053/32.png) [@Harm\_de\_Laat](https://www.ruby-forum.com/u/Harm_de_Laat)\
**Post date:** [January 21, 2006, 3:39pm UTC](https://www.ruby-forum.com/t/related-drop-down-list-ajax/52411/4 "2006-01-21T15:39:59Z")

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On 1/13/06, Harm de Laat [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> def get\_brands\_for\_category  
> @brands = Brand.find\_all\_by\_category\_id (@params[“category\_id”])  
> end
> 
> Somehow it does not work. The related dropdown list does not change  
> contents. Does anybody have an idea why?

Make sure you have a get\_brands\_for\_category.rhtml file like:

\<%= options\_from\_collection\_for\_select @brands, “id”, “name” %\>

And you’ll want to turn off the layout for the get\_brands\_for\_category  
action.