Delete a rails relationship with an :include_blank - ruby-on-rails

Question

I want to be able to select a blank object and post it so that I can clear a rails relationship. By default when you POST while selected on the :include_blank entry, nothing gets posted so it doesn't delete the old relationship. So I'm trying to add a 0 id blank item to the array.
Original:
<%= select_f f,:config_template_id, #operatingsystem.config_templates.where(:template_kind_id => f.object.template_kind_id), :id, :name, {:include_blank => true}, { :label => f.object.template_kind } %>
Mine:
<%= select_f f,:config_template_id, #operatingsystem.config_templates.where(:template_kind_id => f.object.template_kind_id).collect { |c| [c.name, c.id]}.insert(0, ['', 0]) %>
I'm getting a "wrong number of arguments (3 for 5)" error though and can't figure out what I'm missing. Any pointers? (I also can't find select_f anywhere on web, I think google ignores the _ so the search is way to open ended... For rails 3 should I be using something else?)

Answer 1

You've omitted the 3rd, 4th, 5th, and 6th argument you were passing into your original code block. Whatever select_f is, it's expecting at least 5 arguments. In the original you pass the following to select_f (one argument per line for clarity)
f,
:config_template_id,
#operatingsystem.config_templates.where(:template_kind_id => f.object.template_kind_id),
:id,
:name,
{:include_blank => true},
{ :label => f.object.template_kind }
In your new (broken) call you're only passing
f,
:config_template_id,
#operatingsystem.config_templates.where(:template_kind_id => f.object.template_kind_id).collect { |c| [c.name, c.id]}.insert(0, ['', 0])
Use your first method call, just replace the 3rd argument.
f,
:config_template_id,
#operatingsystem.config_templates.where(:template_kind_id => f.object.template_kind_id).collect { |c| [c.name, c.id]}.insert(0, ['', 0])
:id,
:name,
{:include_blank => true},
{ :label => f.object.template_kind }
Finally, if you don't want the :include_blank => true to be passed, but still do want the label, just pass nil or {} to the 5th argument
f,
:config_template_id,
#operatingsystem.config_templates.where(:template_kind_id => f.object.template_kind_id).collect { |c| [c.name, c.id]}.insert(0, ['', 0])
:id,
:name,
nil,
{ :label => f.object.template_kind }
And altogether on one line:
<%= select_f f, :config_template_id, #operatingsystem.config_templates.where(:template_kind_id => f.object.template_kind_id).collect { |c| [c.name, c.id]}.insert(0, ['', 0]), :id, :name, nil, { :label => f.object.template_kind } %>
I can't guarantee this works because I don't know where the API for select_f is or if you created it yourself. This should however nudge you in the right direction.