String “true” and “false” to boolean

Question

I have a Rails application and I\'m using jQuery to query my search view in the background. There are fields q (search term), start_date, end

Answer 1

ActiveRecord provides a clean way of doing this.

def is_true?(string)
  ActiveRecord::ConnectionAdapters::Column::TRUE_VALUES.include?(string)
end

ActiveRecord::ConnectionAdapters::Column::TRUE_VALUES has all of the obvious representations of True values as strings.

Answer 2

Looking at the source code of Virtus, I'd maybe do something like this:

def to_boolean(s)
  map = Hash[%w[true yes 1].product([true]) + %w[false no 0].product([false])]
  map[s.to_s.downcase]
end

Answer 3

You could add to the String class to have the method of to_boolean. Then you could do 'true'.to_boolean or '1'.to_boolean

class String
  def to_boolean
    self == 'true' || self == '1'
  end
end

Answer 4

In Rails 5 you can use ActiveRecord::Type::Boolean.new.cast(value) to cast it to a boolean.

Answer 5

Security Notice

Note that this answer in its bare form is only appropriate for the other use case listed below rather than the one in the question. While mostly fixed, there have been numerous YAML related security vulnerabilities which were caused by loading user input as YAML.

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A trick I use for converting strings to bools is YAML.load, e.g.:

YAML.load(var) # -> true/false if it's one of the below

YAML bool accepts quite a lot of truthy/falsy strings:

y|Y|yes|Yes|YES|n|N|no|No|NO
|true|True|TRUE|false|False|FALSE
|on|On|ON|off|Off|OFF

Another use case

Assume that you have a piece of config code like this:

config.etc.something = ENV['ETC_SOMETHING']

And in command line:

$ export ETC_SOMETHING=false

Now since ENV vars are strings once inside code, config.etc.something's value would be the string "false" and it would incorrectly evaluate to true. But if you do like this:

config.etc.something = YAML.load(ENV['ETC_SOMETHING'])

it would be all okay. This is compatible with loading configs from .yml files as well.

Answer 6

I'm surprised no one posted this simple solution. That is if your strings are going to be "true" or "false".

def to_boolean(str)
    eval(str)
end