Q:

Make blank params[] nil

When a user submits a form and leaves certain fields blank, they get saved as blank in the DB.  I would like to iterate through the params[:user] collection (for example) and if a field is blank, set it to nil before updating attributes.  I can't figure out how to do this though as the only way I know to iterate creates new objects:
coll = params[:user].each do |c|
    if c == ""
       c = nil
    end
end

Thanks.

A:

Consider what you're doing here by using filters in the controller to affect how a model behaves when saved or updated. I think a much cleaner method would be a before_save call back in the model or an observer. This way, you're getting the same behavior no matter where the change originates from, whether its via a controller, the console or even when running batch processes.
Example:
class Customer < ActiveRecord::Base
  NULL_ATTRS = %w( middle_name )
  before_save :nil_if_blank

  protected

  def nil_if_blank
    NULL_ATTRS.each { |attr| self[attr] = nil if self[attr].blank? }
  end
end

This yields the expected behavior:
>> c = Customer.new
=> #<Customer id: nil, first_name: nil, middle_name: nil, last_name: nil>
>> c.first_name = "Matt"
=> "Matt"
>> c.middle_name = "" # blank string here
=> ""
>> c.last_name = "Haley"
=> "Haley"
>> c.save
=> true
>> c.middle_name.nil?
=> true
>>

A:

If you just want to kill the blanks, you can just do params.delete_if {|k,v| v.blank?}.

A:

A good gem for handling this in the model: https://github.com/rmm5t/strip_attributes
It defines a before_validation hook that trims whitespaces and sets empty strings to nil. 

