Rails: Multiple dropdown menus collection_select

Question

Super Rails n00b here: Currently I have a form with the following code:

<%= f.collection_select :account_ids, @accounts, :id, :name, include_blank: true %>         


        

Answer 1

If your parameter name ends in "[]", then all inputs with that name will be collated into an array with that name.

So, your select tag (in html) will be like

<select name="account_ids[]"><option>...

and to make this using the collection_select helper, try

<%= f.collection_select :account_ids, @accounts, :id, :name, {include_blank: true}, {:name => 'account_ids[]'} %>

Answer 2

You need to add one option :multiple :

<%= f.collection_select :account_ids, @accounts, 
                        :id, :name, { include_blank: true },
                         { multiple: true } %>

Note: :multiple- If set to true the selection will allow multiple choices.

I wrote a little snippet to test it. My code :

<%= form_for @track, url: fetch_path do |f| %>
  <%= f.collection_select :label, @tracks, :id, :title, {include_blank: true}, {multiple: true} %>
<% end %>

Here is the page :

Or, if you really want to duplicate:

<% klass = f.object.class.model_name.param_key %>
<%= f.collection_select :account_ids, @accounts, :id, :name, { include_blank: true } , { name: "#{klass}[account_ids][]" } %>

Write the above line 3 times.