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 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       amp start date         search start date   val       amp end date         search end date   val       amp 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

User · Answer

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

User · Answer

Perhaps str to s downcase     true  for completeness  Then nothing can crash even if str is nil or 0

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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     A trick I use for converting strings to bools is YAML load  e g    YAML load var    - gt  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

User · Answer

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

User · Answer

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

User · Answer

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  gt  ActiveRecord  Type  Boolean new type cast from user  true     gt  true  4  pry main  gt  ActiveRecord  Type  Boolean new type cast from user  false     gt  false  5  pry main  gt  ActiveRecord  Type  Boolean new type cast from user  T     gt  true  6  pry main  gt  ActiveRecord  Type  Boolean new type cast from user  F     gt  false  7  pry main  gt  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  lt main gt  at  pry  7    gt  false  8  pry main  gt  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  lt main gt  at  pry  8    gt  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

User · Answer

As far as i know there is no built in way of casting strings to booleans  but if your strings only consist of  true  and  false  you could shorten your method to the following   def to boolean str    str     true  end

User · Answer

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

[jquery] String "true" and "false" to boolean

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