Rails Select Tag and Onchange Event Calling a Remote Function with Default Option Selected

Here is a little code snippet that will fire off a request to update_client_path when you change the select field. This stands alone, rather than being apart of a larger form. The Client::CATEGORY argument is a hash, which I populated manually in my Client.rb model. It is something like this

CATEGORY = {:lead => "Prospective clients", :past => "Previous clients..."}

In my view I have

<%= select_tag "client_category",
 options_for_select(Client::CATEGORY.keys, @client.category.to_sym),
 { :onchange => remote_function( :url => update_client_path(@client), :with=>"'change_to='+this.value+''" ) } %>

One gotcha is that the select_tag, options_for_select argument expects a symbol if you’re passing in a hash as the type of the collection! It may not set the default if you provide it with a string for the second arg (which specifies which option should be set as selected).

You also need to make sure that the url update_client_path is set in your routes file and that your controller (clients_controller in this case) has the appropriate method to handle the request.

Collection Select Helper and OnChange Event in Rails

Given a collection of Active Record objects, you may use the collection_select helper method to produce a select form field. You need to pass in a number of arguments to the helper function.

1) object – your model object used in the collection
2) method – a valid model attribute or method
3) collection – a collection of active record model objects
4) option_value – value being set from the model for the <option value=”option_value”> html element
5) option_name – what is displayed for the user e.g., <option> option_name <
6) option – general options
7) options for the select html element

# helper and arguments...
# collection_select( model, id, collection, option_value, option_name, options, html_options)

<%= collection_select("states", "state_id",
  State.participating,
  "abbreviation", "name",
   {:selected=> get_current_state_or_nil },
   {:onchange=>"document.location='/states/'+this.value"}
) %>

#which will produce something like...

<pre id="line27">&lt;select id="state_id" name="state[id]" onchange="document.location='/states/'+this.value"&gt;
&lt;option value="AL"&gt;Alabama&lt;/option&gt;
&lt;option value="AK"&gt;Alaska&lt;/option&gt;
&lt;option value="AZ"&gt;Arizona&lt;/option&gt;
&lt;option value="AR"&gt;Arkansas&lt;/option&gt;
&lt;/select&gt;

Select Distinct in Rails with Active Record

User.find :all, :select => "DISTINCT occupation"