CODEWITHSUNDEEP
ruby-on-railsparameters
Brendon Muir
Brendon Muir

Reputation: 4612

Define expected parameters for a controller action in Rails

I remember once seeing the ability to define at the top of a controller the parameters that an action requires to work. For the life of me I can't seem to find any mention of that capability anymore and it would be useful for the following:

def sort
  params[:links].each_with_index do |id, index|
    @link_set.links.in_context(context).update_all(['position=?', index+1], ['id=?', id])
  end
  render :nothing => true
end

I'm expecting params[:links] so if some smarty decides to visit that action without giving me params then it fails with nil.each_with_index.

It'd be nice to gracefully give a 404 or something if the parameters are missing without having to code this into every method of this type.

Does this exist? :)

Upvotes: 0

Views: 1078

Answers (3)

Brendon Muir
Brendon Muir

Reputation: 4612

Actually, stumbled across this article: http://rails.nuvvo.com/lesson/6376-action-controller-verification

The method is called verify and you can specify things like parameters to expect. :)

Upvotes: 3

Maz
Maz

Reputation: 3375

Try this code:

before_filter :check_params

private
def check_params
    needed_params=[:links]
    needed_params.each do |x|
        render :text=>"Missing param #{x}", :status=>400
        return
    end

end

Put this code at the end of your class. It will work for every action. Also, you want to return an error code 400 (Bad Request), not an error 404 (File Not Found).

Upvotes: 0

Ryan Bigg
Ryan Bigg

Reputation: 107728

I dont recall functionality existing that allows you to do that. You could use this instead at the top of your action:

params[:links] ||= []

Upvotes: -2

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