Use javascript/prototype to get a text field value for link_to_remote

This one was a headache, and by headache I mean I was literally pounding my head on the desk trying to figure it out.

I wanted to use link_to_remote to create a model from another model’s form. The example being a ‘Product’ model that belongs to a ‘Group’, the user would select which group a product belonged to within the Product form. Within being the key word because you can’t use ‘remote_form_for’ because it will submit the ‘master’ form.

The solution I came up with was to use link_to_remote instead, but how to pass a text_field’s value to link_to_remote’s arguments. After hacking away I gave up and shot an email off to the AHG Software folks who have worked with me on a couple of Rails projects.

The answer was to use prototype’s $F() function which returns the value of any field input control.

<div id="group">
    <ul id="group_list">
        <%= render :partial => 'groups/group_list', :collection => @groups %>
    </ul>
    <% @group = Group.new %>
    <%= text_field 'group','name' %><br />
    <%= link_to_remote "Add Group",
    { :update => "group_list",
    :url => { :controller => "groups", :action => "new"},
    :with => "'group%5Bname%5D='+$F('group_name')",
    :position => :bottom },
    { :class => "add" } %>
</div>

The key line being

:with => "'group%5Bname%5D='+$F('group_name')",

‘%5B’ and ‘%5D’ are opening and closing square brackets [], which become more familiar to Rubyists (Rubians?… San Diegons?) as ‘group[name]‘.

Problem solved! – with a little help