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_date
and internal
. The internal
field is a checkbox and I'm using the is(:checked)
method to build the url that is queried:
$.getScript(document.URL + "?q=" + $("#search_q").val() + "&start_date=" + $("#search_start_date").val() + "&end_date=" + $("#search_end_date").val() + "&internal=" + $("#search_internal").is(':checked'));
Now my problem is in params[:internal]
because there is a string either containing "true" or "false" and I need to cast it to boolean. Of course I can do it like this:
def to_boolean(str)
return true if str=="true"
return false if str=="false"
return nil
end
But I think there must be a more Ruby'ish way to deal with this problem! Isn't there...?
This question is related to
jquery
ruby-on-rails
ruby
ruby-on-rails-3
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
I don't think anything like that is built-in in Ruby. You can reopen String class and add to_bool method there:
class String
def to_bool
return true if self=="true"
return false if self=="false"
return nil
end
end
Then you can use it anywhere in your project, like this: params[:internal].to_bool
You could consider only appending internal
to your url if it is true, then if the checkbox isn't checked and you don't append it params[:internal]
would be nil
, which evaluates to false in Ruby.
I'm not that familiar with the specific jQuery you're using, but is there a cleaner way to call what you want than manually building a URL string? Have you had a look at $get
and $ajax
?
You can use wannabe_bool gem. https://github.com/prodis/wannabe_bool
This gem implements a #to_b
method for String, Integer, Symbol and NilClass classes.
params[:internal].to_b
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.
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
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.
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
In Rails 5 you can use ActiveRecord::Type::Boolean.new.cast(value)
to cast it to a boolean.
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
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.
Perhaps str.to_s.downcase == 'true'
for completeness. Then nothing can crash even if str
is nil or 0.
ActiveRecord::Type::Boolean.new.type_cast_from_user
does this according to Rails' internal mappings ConnectionAdapters::Column::TRUE_VALUES
and ConnectionAdapters::Column::FALSE_VALUES
:
[3] pry(main)> ActiveRecord::Type::Boolean.new.type_cast_from_user("true")
=> true
[4] pry(main)> ActiveRecord::Type::Boolean.new.type_cast_from_user("false")
=> false
[5] pry(main)> ActiveRecord::Type::Boolean.new.type_cast_from_user("T")
=> true
[6] pry(main)> ActiveRecord::Type::Boolean.new.type_cast_from_user("F")
=> false
[7] pry(main)> ActiveRecord::Type::Boolean.new.type_cast_from_user("yes")
DEPRECATION WARNING: You attempted to assign a value which is not explicitly `true` or `false` ("yes") to a boolean column. Currently this value casts to `false`. This will change to match Ruby's semantics, and will cast to `true` in Rails 5. If you would like to maintain the current behavior, you should explicitly handle the values you would like cast to `false`. (called from <main> at (pry):7)
=> false
[8] pry(main)> ActiveRecord::Type::Boolean.new.type_cast_from_user("no")
DEPRECATION WARNING: You attempted to assign a value which is not explicitly `true` or `false` ("no") to a boolean column. Currently this value casts to `false`. This will change to match Ruby's semantics, and will cast to `true` in Rails 5. If you would like to maintain the current behavior, you should explicitly handle the values you would like cast to `false`. (called from <main> at (pry):8)
=> false
So you could make your own to_b
(or to_bool
or to_boolean
) method in an initializer like this:
class String
def to_b
ActiveRecord::Type::Boolean.new.type_cast_from_user(self)
end
end
There isn't any built-in way to handle this (although actionpack might have a helper for that). I would advise something like this
def to_boolean(s)
s and !!s.match(/^(true|t|yes|y|1)$/i)
end
# or (as Pavling pointed out)
def to_boolean(s)
!!(s =~ /^(true|t|yes|y|1)$/i)
end
What works as well is to use 0 and non-0 instead of false/true literals:
def to_boolean(s)
!s.to_i.zero?
end
Source: Stackoverflow.com