CODEWITHSUNDEEP
ruby-on-railsruby
Gareth Burrows
Gareth Burrows

Reputation: 1182

Switching between two boolean values in Ruby

I have the following code in a controller action, which looks at a user, and changes a boolean value to the opposite value, so if the user is true then it becomes false, and vice versa:

  if current_user.enable_access
    current_user.update_attribute(:enable_access, false) 
  else
    current_user.update_attribute(:enable_access, true) 
  end

Is there a neater way of writing this?

Upvotes: 2

Views: 1698

Answers (6)

Beulah Akindele
Beulah Akindele

Reputation: 649

I believe the DRY way to accomplish it would be to use:

current_user.enable_access = !current_user.enable_access

Then you could just write a method on a model and call it from any controller.

user.rb

def enable_user_access
    self.enable_access = !self.enable_access
end

then calling it from a controller

current_user.enable_user_access

Upvotes: 1

Drenmi
Drenmi

Reputation: 8777

How about using the toggle method that was specifically intended for this? 

current_user.toggle(:enable_access)

If you want to add persistence in one character, there's also the toggle! method.

current_user.toggle!(:enable_access)

Upvotes: 7

Aleksei Matiushkin
Aleksei Matiushkin

Reputation: 121000

While the answer by @Зеленый is absolutely correct I wondered, that there is no DRY way to accomplish such a silly task.

The problem is that true and false in Ruby are instances of different classes, TrueClass and FalseClass respectively. That said, one can not just switch the boolean value inplace.

But what we can imagine, mediating at update_attribute source? Probably this is a shortest way to accomplish your task (please, do not use it at home, it’s a joke after all.)

current_user.tap do |cu|
  cu.enable_access ^= true
end.save validate: false

I just reinvented toggle!, thanks @Dremni for pointing this out.

Upvotes: 3

scorix
scorix

Reputation: 2516

current_user.toggle!(:enable_access)

http://api.rubyonrails.org/classes/ActiveRecord/Persistence.html#method-i-toggle-21

Upvotes: 1

the Tin Man
the Tin Man

Reputation: 160551

Here's something to meditate on:

false # => false
true # => true

!false # => true
!true # => false

foo = false # => false
!foo # => true
foo = !foo # => true

foo = nil # => nil
!foo # => true

foo = !nil # => true
foo = !false # => true

Notice !!, which is a convenient way to turn a value into a true/false:

foo = !!nil # => false
foo = !!false # => false

foo = 1 # => 1
!foo # => false
!!foo # => true

foo = 'a' # => "a"
!foo # => false
!!foo # => true

0 == 1 # => false
1 == 1 # => true

'a' == '' # => false
'a' == 'a' # => true

These are the building blocks for comparisons in Ruby.

Upvotes: 3

Roman Kiselenko
Roman Kiselenko

Reputation: 44370

In one line, if current_user.enable_access can be only true`false`:

current_user.update_attribute(:enable_access, !current_user.enable_access)

Upvotes: 6

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