Dropdown onchange event?

Rails
1

Hi,
I have a dropdown menu which shows the categories available. When a user
selects one I want the browser to redirect to the selected category.
I now have this code I found on stackoverflow;

<%form_for :cat_form, :url => {:action => :viewflokkur_selected} do
|f|%>
<%= f.select :cat, @cats_for_mt, {:include_blank => “Flokkar
mælitækis”}, :onchange =>
‘window.location.href = “viewflokkur/” +
this.getAttribute(“value”)’%>
<%end%>

However, “value” appears to be null everytime, so I get thrown to
http://localhost:3000/categories/viewflokkur/null. Is there something I
need to do for this to work, or should I be doing something else? I
don’t really understand how to use observer_fields either, but that
seems to be something I should be looking into, is it not?

Best regards,
Sindri

2

this.getAttribute(“value”) won’t work on a select input, since the
select doesn’t have a “value” attribute. Rather, it has a list of
options, and one or more of them are selected.

Try this.selectedIndex.value instead.

3

Tim S. wrote:

this.getAttribute(“value”) won’t work on a select input, since the
select doesn’t have a “value” attribute. Rather, it has a list of
options, and one or more of them are selected.

Try this.selectedIndex.value instead.

Thanks for the suggestion, this.selectedIndex.value does not work
though, now I get
http://localhost:3000/categories/viewflokkur/undefined. Anywhere I can
look this up? :slight_smile:

4

Please post the HTML that is output from the form.

5

Hi,

This is the output HTML.

Flokkar mælitækis Almennt Hjartasjúkraþjálfun Lungnasjúkraþjálfun Taugasjúkraþjálfun Öldrunarsjúkraþjálfun

BR,
Sindri

6

Finally got it working, used this solution;

<%= select_tag “cat_selected”, options_for_select([‘Flokkar
mælitækis’]+@cats_for_mt),
:onchange => ‘window.location.href = “viewflokkur_from_select/” +
this.selectedIndex’%>

That gave me params[:id] = index-selected, so I created this new method
viewflokkur_from_select wich gets @cats_for_mt[params[:id].to_i-1] and
then redirects to viewflokkur with that value as params[:cat]. Not very
pretty, and a whole lot uglier than I expected, but works…

Thanks everyone for the suggestions!

7

Hi again,

I’ve also been trying to solve this using observe_field, and that
‘almost’ seems to work. Here’s the code:

<%=select_tag “cat_selected”, options_for_select(@cats_for_mt)%>
<%=observe_field ‘cat_selected’,
:url => {:action => :viewflokkur},
:with => ‘cat’,
:method => :get %>

When I change the value, development.log shows this.

Processing CategoriesController#viewflokkur (for 127.0.0.1 at 2010-06-12
12:04:33) [GET]
Parameters: {“cat”=>“Taugasjúkraþjálfun”,
“authenticity_token”=>“B2u5ULNr7IJ/ta0+hiAMBjmjEtTtc/yMAQQvSxFn2d0=”}
Rendering template within layouts/main
Rendering categories/viewflokkur
Completed in 21ms (View: 18, DB: 0) | 200 OK
[http://localhost/categories/viewflokkur?cat=Taugasjúkraþjálfun&authenticity_token=B2u5ULNr7IJ%2Fta0%2BhiAMBjmjEtTtc%2FyMAQQvSxFn2d0%3D]

So I should be redirected to ‘viewflokkur’, but nothing happens in my
browser. Is there something else I need to do?

BR,
Sindri

8

Hi,
Try this if you wish to have your code clean :