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Rails 5 ArrayInquirer and checking array contents

on May 27, 2016
This blog is part of our Rails 5 series.

Rails 5 introduces Array Inquirer that wraps an array object and provides friendlier methods to check for the presence of elements that can be either a string or a symbol.

1
2pets = ActiveSupport::ArrayInquirer.new([:cat, :dog, 'rabbit'])
3
4> pets.cat?
5#=> true
6
7> pets.rabbit?
8#=> true
9
10> pets.elephant?
11#=> false
12

Array Inquirer also has any? method to check for the presence of any of the passed arguments as elements in the array.

1
2pets = ActiveSupport::ArrayInquirer.new([:cat, :dog, 'rabbit'])
3
4> pets.any?(:cat, :dog)
5#=> true
6
7> pets.any?('cat', 'dog')
8#=> true
9
10> pets.any?(:rabbit, 'elephant')
11#=> true
12
13> pets.any?('elephant', :tiger)
14#=> false
15

Since ArrayInquirer class inherits from Array class, its any? method performs same as any? method of Array class when no arguments are passed.

1
2pets = ActiveSupport::ArrayInquirer.new([:cat, :dog, 'rabbit'])
3
4> pets.any?
5#=> true
6
7> pets.any? { |pet| pet.to_s == 'dog' }
8#=> true
9

Use inquiry method on array to fetch Array Inquirer version

For any given array we can have its Array Inquirer version by calling inquiry method on it.

1
2pets = [:cat, :dog, 'rabbit'].inquiry
3
4> pets.cat?
5#=> true
6
7> pets.rabbit?
8#=> true
9
10> pets.elephant?
11#=> false
12

Usage of Array Inquirer in Rails code

Rails 5 makes use of Array Inquirer and provides a better way of checking for the presence of given variant.

Before Rails 5 code looked like this.

1
2request.variant = :phone
3
4> request.variant
5#=> [:phone]
6
7> request.variant.include?(:phone)
8#=> true
9
10> request.variant.include?('phone')
11#=> false
12

Corresponding Rails 5 version is below.

1
2request.variant = :phone
3
4> request.variant.phone?
5#=> true
6
7> request.variant.tablet?
8#=> false
9

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