get :new do
    @clients = Client.all
    @software = SiteSoftware.all
    @site = Site.new
    render 'sites/new'

end


<div class="group">
  <%= f.label :client_id %><%= f.error_message_on :client_id %><br /><br />
  <%= f.select(:client_id, :collection => @clients, :fields => [:name, :id])%>
 <span class="description">Pick the Site Client</span>
</div>

# Define collections in the controller for use in the form:

get :new do
    @clients = Client.all
    @software = SiteSoftware.all
    @site = Site.new
    render 'sites/new'

end

# And in the form, use the collections:

<div class="group">
  <%= f.label :client_id %><%= f.error_message_on :client_id %><br /><br />
  <%= f.select(:client_id, :collection => @clients, :fields => [:name, :id])%>
 <span class="description">Pick the Site Client</span>
</div>

# Define collections in the controller for use in the form:

get :new do
    @clients = Client.all
    @software = SiteSoftware.all
   
    @site = Site.new
    render 'sites/new'

end




# And in the form, use the collections:

<div class="group">
  <%= f.label :client_id %><%= f.error_message_on :client_id %><br /><br />
  <%= f.select(:client_id, :collection => @clients, :fields => [:name, :id])%>
 <span class="description">Pick the Site Client</span>
</div>

# Define collections in the controller for use in the form:

get :new do
    @clients = Client.all
    @software = SiteSoftware.all
   
    @site = Site.new
    render 'sites/new'

end




# And in the form, use the collections:

<div class="group">
  <%= f.label :client_id %><%= f.error_message_on :client_id %><br /><br />
  <%= f.select(:client_id, :collection => @clients, :fields => [:name, :id])%>
 <span class="description">Pick the Site Client</span>
</div>

Padrino Select from Collection

Rails