convincing form_for to generate params for parent class

rubyonrails-talk
1

I have an STI class structure:

class MeteredService < ActiveRecord::Base ; end class PGEService < MeteredService ; end class SCEService < MeteredService ; end

In my view, I want update (say) the :resource field:

<%= form_for(metered_service, :url => metered_service_path(metered_service)) do |f| %>   <%= f.text_field 'resource' %>   <%= f.submit "update" %> <% end %>

But this generates a params hash referring to (e.g.) the PGEService subclass rather than the MeteredService parent class:

params = {   "utf8"=>"✓",   "_method"=>"put",   "authenticity_token"=>"bAKcTUYbLZyGcMJPyf3zEiyjlB8aQlRv4lqZdiwElhE=",   "pge_service"=>{"resource"=>"gas"},   "commit"=>"update",   "action"=>"update",   "controller"=>"metered_services",   "id"=>"54"}

While I could put code in my metered_services_controller to recognize the subclass:

def update   @ms = MeteredService.find(params[:id])   if @ms.update_attributes(params[@ms.class.name.underscore])   ... end

... that doesn't smell right to me. There must be some Rails-appropriate trick that will let me write the canonical:

def update   @ms = MeteredService.find(params[:id])   if @ms.update_attributes(params[:metered_service])   ... end

Am I right? What's the trick?

2

I have an STI class structure:

class MeteredService < ActiveRecord::Base ; end class PGEService < MeteredService ; end class SCEService < MeteredService ; end

In my view, I want update (say) the :resource field:

<%= form_for(metered_service, :url => metered_service_path(metered_service)) do |f| %> <%= f.text_field 'resource' %> <%= f.submit "update" %> <% end %>

But this generates a params hash referring to (e.g.) the PGEService subclass rather than the MeteredService parent class:

params = { "utf8"=>"✓", "_method"=>"put", "authenticity_token"=>"bAKcTUYbLZyGcMJPyf3zEiyjlB8aQlRv4lqZdiwElhE=", "pge_service"=>{"resource"=>"gas"}, "commit"=>"update", "action"=>"update", "controller"=>"metered_services", "id"=>"54"}

While I could put code in my metered_services_controller to recognize the subclass:

def update @ms = MeteredService.find(params[:id]) if @ms.update_attributes(params[@ms.class.name.underscore]) ... end

... that doesn't smell right to me. There must be some Rails-appropriate trick that will let me write the canonical:

def update @ms = MeteredService.find(params[:id]) if @ms.update_attributes(params[:metered_service]) ... end

Am I right? What's the trick?

You might try form_for :metered_service, metered_service, ...

I also have vague memories of overwriting model_name in order to get sti classes to behave nicely with a single set of resourceful routes/controllers

Fred