Ruby: delete multiple hash keys

Question

I often find myself writing this:

params.delete(:controller)  
params.delete(:action)  
params.delete(:other_key)  
redirect_to my_path(params)

The trail of deletes doesn't feel right and neither does:

[:controller, :action, :other_key].each do |k|
  params.delete(k)
end

Is there anything simpler and cleaner?

Answer 1

Fire up a monkey patch?

class Hash
  def delete_keys!(*keys)
    keys.flatten.each do |k|
      delete(key)
    end

    self
  end

  def delete_keys(*keys)
    _dup = dup
    keys.flatten.each do |k|
      _dup.delete(key)
    end

    _dup
  end
end

Answer 2

I don't know what you think is wrong with your proposed solution. I suppose you want a delete_all method on Hash or something? If so, tadman's answer provides the solution. But frankly, for a one-off, I think your solution is extremely easy to follow. If you're using this frequently, you might want to wrap it up in a helper method.

Answer 3

Another way to phrase dmathieu's answer might be

params.delete_if { |k,v| [:controller, :action, :other_key].include? v }

Answer 4

I'd be completely happy with the code you originally posted in your question.

[:controller, :action, :other_key].each { |k| params.delete(k) }

Answer 5

I'm guessing you're unaware of the Hash#except method ActiveSupport adds to Hash.

It would allow your code to be simplified to:

redirect_to my_path(params.except(:controller, :action, :other_key))

Also, you wouldn't have to monkey patch, since the Rails team did it for you!

Answer 6

While using Hash#except handles your problem, be aware that it introduces potential security issues. A good rule of thumb for handling any data from visitors is to use a whitelist approach. In this case, using Hash#slice instead.

params.slice!(:desired_param_1, :desired_param_2)

redirect_to my_path(params)