Whitelisting Nested Parameters in Rails

Question

I have a params hash with the following structure (it was built using fields_for)

=> {"utf8"=>"✓",
    "daily_log"=>
      {"id"=>"1",
       "entries_attributes"=>
          {"0"=>
              {"count"=>"",
               "hours"=>"",
               "minutes"=>"",
              }
          }
       },
    "controller"=>"entries",
    "action"=>"create"}

I'm trying to create a an entries_attributes_params method which should just return a whitelisted version of params['daily_log']['entries_attributes'] . Unfortunately, this keeps coming back as {} when I call the method.

The following works

def entries_attributes_params`
   params[:daily_log][:entries_attributes].permit!
end

But i want to avoid using permit! . So I tried the following:

def entries_attributes_params
    params[:daily_log][:entries_attributes].permit(:count, :hours, :minutes)
end

This doesn't work. I get {} back.

I tried wrapping the attributes I pass into permit with [] , but that doesn't work.

...permit([...attributes...])

How do I do this?

Answer 1

Try this:

def entries_attributes_params
  params_hash = params.require(:daily_log).permit(:id, entries_attributes: [:count, :hours, :minutes])
  params_hash[:entries_attributes]
end

Answer 2

Figured it out. The key is to recognize that params.permit ... doesn't actually change the main params hash. It creates a new object. Combining this idea with KM's solution below gives the full answer:

def entries_attributes_params
  p = params.require(:daily_log).permit(:id, entries_attributes: [:count, :hours, :minutes])
  p[:entries_attributes]
end