AutoStripAttributes helps to remove unnecessary whitespaces from ActiveRecord or ActiveModel attributes. It's good for removing accidental spaces from user inputs (e.g. when user copy/pastes some value to a form and the value has extra spaces at the end).

It works by adding a before_validation hook to the record. No other methods are added. Gem is kept as simple as possible.

Gem has option to set empty strings to nil or to remove extra spaces inside the string.

Gem Gem

Howto / examples

Include gem in your Gemfile:

gem "auto_strip_attributes", "~> 2.2"
class User < ActiveRecord::Base

  # Normal usage where " aaa  bbb\t " changes to "aaa  bbb"
  auto_strip_attributes :nick, :comment

  # Squeezes spaces inside the string: "James     Bond  " => "James Bond"
  auto_strip_attributes :name, :squish => true

  # Won't set to null even if string is blank. "   " => ""
  auto_strip_attributes :email, :nullify => false

  # Use with attributes that are not mapped to a column
  auto_strip_attributes :password, virtual: true


Default options

By default the following options are defined (listed in the order of processing):

  • :strip (enabled by default) - removes whitespaces from the beginning and the end of string
  • :nullify (enabled by default) - replaces empty strings with nil
  • :squish (disabled by default) - replaces extra whitespaces (including tabs) with one space
  • :delete_whitespaces (disabled by default) - delete all whitespaces (including tabs)
  • :convert_non_breaking_spaces (disabled by default) - converts non-breaking spaces to normal spaces (Unicode U+00A0)
  • :virtual (disabled by default) - By default auto_strip_attributes doesn't work with non-persistent attributes (e.g., attributes that are created with attr_accessor). This is to avoid calling their custom getter/setter methods. Use this option with non-persistent attributes.

Custom Filters

Gem supports custom filtering methods. Custom methods can be set by calling to set_filter method inside a block passed to AutoStripAttributes::Config.setup. set_filter method accepts either Symbol or Hash as a parameter. If parameter is a Hash, the key should be filter name and the value is boolean whether filter is enabled by default or not. Block should return processed value.

This is an example on how to add html tags stripping in Rails

E.g. inside config/initializers/auto_strip_attributes.rb

AutoStripAttributes::Config.setup do
  set_filter :strip_html => false do |value|
    ActionController::Base.helpers.strip_tags value

And in the model:

class User < ActiveRecord::Base
  auto_strip_attributes :extra_info, :strip_html => true

Change the order of filters is done by manipulating filters_order array. You may also enable or disable filter by default by changing filters_enabled hash.

Example of making :strip_html filter first and enabling :squish by default

AutoStripAttributes::Config.setup do
  filters_order.insert(0, :strip_html)
  filters_enabled[:squish] = true

AutoStripAttributes::Config.setup accepts following options

  • :clear => true, to clear all filters
  • :defaults => true, to set three default filters mentioned above



Gem has been tested with newest Ruby & Rails combination and it probably works also with older versions. See test matrix at!/holli/auto_strip_attributes


Submit suggestions or feature requests as a GitHub Issue or Pull Request. Remember to update tests. Tests are quite extensive.

Other approaches

This gem works by adding before_validation hook and setting attributes with self[attribute]=stripped_value. See:

Other approaches could include calling attribute= from before_validation. This would end up calling possible custom setters twice. Might not be desired effect (e.g. if setter does some logging).

Method chaining attribute= can be also used. But then stripping would be omitted if there is some code that calls model[attribute]= directly. This could happen easily when using hashes in some places.

Similar gems

There are many similar gems. Most of those don't have :squish or :nullify options. Those gems might have some extra methods whereas this gem is kept as simple as possible. These gems have a bit different approaches. See discussion in previous chapter.


Released under the MIT license (