How to remove a string from an array with Ruby 2.5.3?

Question

I develop on Ruby on Rails 5.2. With the purpose of managing translations, I wish to allow the user to select a language which is different from his current language. The list of configured languages of the application is

 all_languages = I18n.config.available_locales

all_languages is an Array. puts all_languages returns:

en fr de it

The user language is defined in the users table. A method returns current user's language

user_language = current_user.language

user_language is a String. puts user_language returns:

en

I try to apply the delete(obj) method to the array, but this does not alter the array:

all_languages.delete(user_language)

I try to work on arrays only, still it does not alter the languages array:

remove_language = Array.new
remove_language << user_language

puts remove_language returns:

en

puts all_languages - remove_language returns:

en fr de it

where the en language should be removed. I don't understand why it remains in the list!

Use p instead of puts, which will show the object in more detail. puts removes information such as whether you have a bare item or an array that includes it, as well as whether you have a string or a symbol. — sawa
– sawa, Commented Nov 30, 2018 at 7:11
I'm not understanding why your last attempt using array - array isn't working. Check my answer. Try it rails console. — Dom
– Dom, Commented Nov 30, 2018 at 7:51
"user_language is a String" – consider turning that into a symbol. — Stefan
– Stefan, Commented Nov 30, 2018 at 11:13
@SergioTulentsev sure, but current_user.language is a method call. You could override language or maybe have the ORM convert it. The code becomes easier if you are dealing with the correct "type" right from the start. — Stefan
– Stefan, Commented Nov 30, 2018 at 11:26

Sergio Tulentsev · Accepted Answer · 2018-11-30 11:04:58Z

7

I18n.config.available_locales returns symbols *. And your current_user.language is a string. "en" is not at all the same thing as :en. That said, this should work:

all_languages = I18n.config.available_locales.dup # copy the array
all_languages.delete(:en)
# or, for your case
all_languages.delete(current_user.language.to_sym)


# non-mutating way
all_langs_without_en = I18n.config.available_locales.reject { |loc| loc == :en }

_{* at least in rails 4.2, where I checked this.}

edited Nov 30, 2018 at 11:04

answered Nov 30, 2018 at 7:53

Sergio Tulentsev

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5 Comments

Sergio Tulentsev Over a year ago

@Jurgen: thanks, but sawa called it 50 mins ago, and nobody listened :)

3limin4t0r Over a year ago

Alternatively you could change the available locales into strings instead of changing to user language into a symbol. all_languages = I18n.config.available_locales.map(&:to_s)

Sergio Tulentsev Over a year ago

@Stefan: why did I think it was duping the array? :facepalm:

Stefan Over a year ago

It probably depends on the backend being used, but unless the API guarantees it, dup is the safer choice. BTW, in Rails there's also Array#without.

Sergio Tulentsev Over a year ago

@Stefan: ah, Array#without. I was wondering why something like that doesn't exist. Post that as an answer :)

Stefan · Accepted Answer · 2018-11-30 11:26:35Z

1

Your code doesn't work, because available_locales returns an array of symbols and you are attempting to remove a string.

a = [:en, :fr, :de, :it]
a.delete('en')
#=> nil

a #=> [:en, :fr, :de, :it]

To fix this, you have to turn your string into a symbol. Furthermore, you should avoid delete because it modifies the receiver (modifying available_locales might result in bugs later on). You can use Rails' Array#without instead which returns a new array:

all_languages = I18n.config.available_locales
#=> [:en, :fr, :de, :it]

user_language = current_user.language.to_sym
#=> :en

all_languages.without(user_language)
#=> [:fr, :de, :it]

answered Nov 30, 2018 at 11:26

Stefan

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1 Comment

user1185081 Over a year ago

Thank you all! I finally took the solution of Johan Wentholt to convert to an array of strings and use it .without(user_language).

Talha Junaid · Accepted Answer · 2018-11-30 07:03:00Z

1

Try this

all_languages = ["en","fr","de","it"]
user_language = "en"
all_languages.delete_at(all_languages.index(user_language))

#=> ["fr","de","it"]

answered Nov 30, 2018 at 7:03

Talha Junaid

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3 Comments

Sergio Tulentsev Over a year ago

The delete should have worked. What makes it fail, will prevent this one from working too.

Talha Junaid Over a year ago

I believe delete is not working because of conflict with active record delete method. Is it possible?

Sergio Tulentsev Over a year ago

No, that is not what's happening.

killernova · Accepted Answer · 2018-11-30 07:00:01Z

0

This solution should meet your need:

l = I18n.config.available_locales
l.pop
I18n.config.available_locales = l

answered Nov 30, 2018 at 7:00

killernova

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2 Comments

Dom Over a year ago

op wants to remove the user's selected language, your method doesn't guarantee you're removing the right item in the array.

killernova Over a year ago

This is just an example, and if you want to remove the specific item, you could use delete method to get the desired array and then assign it to I18n.config.available_locales

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