# Form.select with :onChange event help

**URL:** <https://www.ruby-forum.com/t/form-select-with-onchange-event-help/133967>\
**Category:** Rails\
**Created:** [April 5, 2008, 8:26pm UTC](https://www.ruby-forum.com/t/form-select-with-onchange-event-help/133967 "2008-04-05T20:26:03Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![addywaddy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/ea5d25/32.png) [@addywaddy](https://www.ruby-forum.com/u/addywaddy)\
**Post date:** [April 5, 2008, 8:26pm UTC](https://www.ruby-forum.com/t/form-select-with-onchange-event-help/133967/1 "2008-04-05T20:26:03Z")

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Hey everyone,

As a quick elaboration: I’m trying to make an Admin panel which lists  
the CRUD actions for several models. The use case calls for a drop-down  
box for the user to be able to select the object they want to perform an  
action on and then links to different actions.

What I started with is the following:

\<% form\_for :major do |form| %\>  
\<%=  
@majors = Major.find(:all, :order =\> “name” ).map {|u| [u.name, u.id] }  
form.select(:major\_id, @majors)  
%\>  
\<%= link\_to ‘Show’, :action =\> ‘show’, :id =\> :major\_id %\>  
\<%= link\_to ‘Edit’, :action =\> ‘edit’, :id =\> :major\_id %\>  
\<%= link\_to ‘Destroy’, { :action =\> ‘destroy’, :id =\> :major\_id },  
:confirm =\> ‘Are you sure?’, :method =\> :post %\>  
\<% end %\>

What I want it to do is take the selected id and pass it to the action,  
but so far it either interprets ‘major\_id’ literally as the id or passes  
the entire array from the drop-down box. Needless to say, it hasn’t been  
working.

What someone has suggested I do is:

1. Use JS for the onchange event on the dropdown, and have it update the  
link hrefs.
2. Have all the actions links load via RJS on the onchange event.

I’m not familiar with RJS at all really, but I looked at some posts  
about similar problems and came up with the following:

\<% form\_for :major do |form| %\>  
\<%= form.collection\_select(:major, Major.find(:all, :order =\> ‘name’),  
:id, :name, {:prompt =\> true}, :onChange =\> remote\_function(:url =\>  
‘list’, :with =\> “’:id=’ + this.value”) ) %\>  
\<%= link\_to ‘Show’, :action =\> ‘show’, :id =\> params[:id] %\>  
\<%= link\_to ‘Edit’, :action =\> ‘edit’, :id =\> params[:id] %\>  
\<%= link\_to ‘Destroy’, { :action =\> ‘destroy’, :id =\> params[:id] },  
:confirm =\> ‘Are you sure?’, :method =\> :post %\>  
\<% end %\>

Unfortunately, it still appears to be a failure. I also saw mention to  
using this, but am even less sure of how it works:

:onChange =\> "new Ajax.Request(this.value, {asynchronous:true,  
evalScripts:true})

If you’ve got some ideas on how to get this to work or could if you can  
help clear up what I am doing wrong, it would be really helpful. Thanks  
in advance!

---

<div class="post-metadata">

**Author:** ![addywaddy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/ea5d25/32.png) [@addywaddy](https://www.ruby-forum.com/u/addywaddy)\
**Post date:** [April 6, 2008, 9:55am UTC](https://www.ruby-forum.com/t/form-select-with-onchange-event-help/133967/2 "2008-04-06T09:55:02Z")

</div>

Honestly I’m not sure what your trying to accomplish?

I would be so bold as to suggest though that the solution is not  
technical.  
Rather that you should change your design.

---

<div class="post-metadata">

**Author:** ![addywaddy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/ea5d25/32.png) [@addywaddy](https://www.ruby-forum.com/u/addywaddy)\
**Post date:** [April 6, 2008, 10:21am UTC](https://www.ruby-forum.com/t/form-select-with-onchange-event-help/133967/3 "2008-04-06T10:21:59Z")

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Use the observe\_field function to setup a AJAX call to the back end to  
populate the area of the form that contains the details of the object  
and move the object details to a partial. You can also try assigning  
the value of the select field to a class variable like @major\_id in  
the backend and use that in your link\_to calls as :id=\>@major\_id  
I don’t think using plain link\_to will result in a form submit action  
that is required for you to get the value of the select field. Look  
at the messages in the server console to see what is getting passed  
back to the server.

On Apr 5, 11:26 pm, Adam G. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)