Unpacking the Rails I18n Toolkit

Originally presented at RailsConf 2025 in Philadelphia.

Transcript

1. Unpacking the Rails I18n Toolkit Chris Fung - RailsConf 2025 Internationalization on Rails 🌐 🚄 Source: Photo by Isaac Chou on Unsplash
2. Sta ff Engineer @ 💙 Binti 🐘 @aergonaut@ruby.social 🦋 @aergonaut.com Chris Fung
3. • We believe every child deserves a loving family! • 550 + agencies in 36 states, serving 46% of children in care nationwide • 85,000 + families; 12,000 + social workers; 20 - 40% time saved What is 💙 Binti?
4. Why should you care about localization?
5. Localization a.k.a. l10n. To adapt content from one locale into another.
6. Locale A combination of a language and region (and script). Often presented as codes: en, fr-CA, zh-Hant-HK
7. Internationalization a.k.a. i18n. To adapt software so it can easily support many different locales.
9. Who speaks English as a second language?
10. Who knows someone who speaks ESL?
11. 1.5 billion / 8B Worldwide English speakers / total population Source: https://www.statista.com/chart/26884/languages-on-the-internet/
12. 21.7% US residents speak a language other than English at home Source: https://www.census.gov/acs/www/about/why-we-ask-each-question/language/
13. 8.2% US residents speak English less than very well Source: https://www.census.gov/acs/www/about/why-we-ask-each-question/language/
15. So you want to localize…
16. Rails makes this very easy! 1. Translate UI text 2. Adapt to different data formatting patterns 3. Support different pluralization grammar 4. Support different rules for constructing lists
17. Part I - Translate your text
18. 1.1 - Externalize your text
19. 1.1 - Externalize! <div> <h1>Create a Post</h1> <p>Write your Post below</p> </div>
20. 1.1 - Externalize! translate(key, **options) An identifier, like “greeting ” or “errors.not_found ” Used for various purposes, mostly variables
21. 1.1 - Externalize! I18n. wi th_locale(:en) { translate("greeting") } #=> "Hello, world!" I18n. wi th_locale(:fr) { translate("greeting") } #=> "Bonjour, le monde!"
22. 1.1 - Externalize! <div> <h1>Create a Post</h1> <p>Write your Post below</p> </div>
23. 1.1 - Externalize! <div> <h1><%= t("posts.ne w .title") %></h1> <p><%= t("posts.ne w .cta") %></p> </div>
24. 1.1 - Externalize! # config/locales/en.y ml en: posts: new: title: Create a Post cta: Write your Post below
25. 1.1 - Externalize! class PostsController < ApplicationController def create unless @post.valid? flash[:error] = "Could not save" end end end
26. 1.1 - Externalize! class PostsController < ApplicationController def create unless @post.valid? flash[:error] = t("errors.could_not_save") end end end
27. 1.2 - Choose your target locales
30. 1.2 - Choose locale codes • Use online tools to find appropriate codes for each language • https://r12a.github.io/app-subtags/index.html • Follow a standard format for your locale codes • IETF language tag: en, pt-BR • GNU language code: pt_BR
31. 1.3 - Translate!
32. 1.3 - Translate! 🚪 Hire a Language Services Provider ( LSP ) 🚪 AI Machine Translation ( MT )
33. 💎 i18n-tasks
34. 1.3 - i18n-tasks • Add gem 'i18n-tasks', group: :development • Choose a translation provider, e.g. Google Translate • Put your Google Translate API key in GOOGLE _T RANSLA TE _API_KEY • Run i18n-tasks translate- m i ssing -f en -l <locales…>
37. Part II - Advanced Localization
38. Localization is about more than just text! 🔣
39. 2.1 - Localizing dates
40. 2.1 - Localizing dates <ul> <li> Posted on: <%= @post.created_at.strft im e("%B %d %Y”) %> </li> </ul>
41. 2.1 - Localizing dates <ul> <li> <%= t("posts.posted_on", date: @post.created_at.strft i m e("%d %B %Y") %> </li> </ul>
42. 2.1 - Localizing dates # en.y ml posts: show: posted_on: Posted on % {date}
43. 2.1 - Localizing dates # ja.y ml posts: show: posted_on: " % {date}౤ߘ"
47. 2.1 - Localizing dates localize(object, **options) A date, time, or number Used for various purposes, like different formats
48. 2.1 - Localizing dates <ul> <li> <%= t("posts.posted_on", date: @post.created_at.strft i m e("%B %d %Y") %> </li> </ul>
49. 2.1 - Localizing dates <ul> <li> <%= t("posts.posted_on", date: l( @ post.created_at)) %> </li> </ul>
50. 2.1 - Localizing dates # en.y ml date: formats: default: "%B %d %Y"
51. 2.1 - Localizing dates # ja.y ml date: formats: default: "???"
55. 💎 t w i tter_cldr
56. 2.1 - twitter_cldr require ' tw i tter_cldr' locale = :en date_style = { type: :long } T wi tterCldr::DataReaders::DateDataReader.ne w ( locale, date_style ).pattern # => "MMMM d, y"
57. 2.1 - twitter_cldr locale = :ja T wi tterCldr::DataReaders::DateDataReader.ne w ( locale, date_style ).pattern # => "y೥M݄d೔"
58. 2.1 - Shopify/worldwide CLDR _T O_ S T R FT IM E _M AP = { cccc: "%A", # Weekday, full form (e.g. "Wednesday") EEEE: "%A", # Weekday, full form (e.g. "Wednesday") LLLL: "%B", # Month, full name (e.g. "December") MMMM: "%B", # Month, full name (e.g. "December") ccc: "%a", # Weekday, abbreviated form (e.g. "Wed.") EEE: "%a", # Weekday, abbreviated form (e.g. "Wed.") LLL: "%b", # Month, abbreviated name (e.g. "Dec.") MMM: "%b", # Month, abbreviated name (e.g. "Dec.") dd: "%02d", # Day of month, zero padded (00..31) hh: "%02l", # Hour, zero padded (01..12) HH: "%02k", # Hour, zero padded (00..23) mm: "%M", # M i nute (00..59) MM: "%02m", # Month of year, zero padded (01..12) ss: " %S ", # Second (00..60) yy: "%02y", # Year, t w o digits (e.g. 19) a: "%P", # am/pm indicator b: "%P", # Should be am/noon/pm/ m i dnight; use am/ pm B: "%P", # Should be "in the morning"/"in the evening"; use am/pm d: "%-d", # Day of month, no padding (1..31) E: "%A", # Weekday (e.g. Wednesday) h: "%-l", # Hour (1..12) H: "%02k", # Hour (0..23) m: "%-M", # M i nute, no padding (0..59) M: "%-m", # Month of the year, no padding (1..12) s: "%-S", # Second, no padding (0..60) v: "%z", # T i m e zone offset (e.g., -0500) y: "%Y", # Year, all digits (e.g. 2019) z: "%z", # T i m e zone offset (e.g., -0500) xxx: "%:z" # T im e zone offset w i th colon (e.g., -05:00) }
59. 2.1 - Localizing dates # ja.y ml date: formats: default: "%Y೥%-m݄%-d೔"
60. 2.1 - Localizing dates I18n. wi th_locale(:en) do I18n.t("posts.posted_on", date: I18n.l(date)) end #=> "Posted on July 13 2025"
61. 2.1 - Localizing dates I18n. wi th_locale(:ja) do I18n.t("posts.posted_on", date: I18n.l(date)) end #=> "2025೥7݄13೔ʹ౤ߘ"
62. 2.2 - Plural rules
63. 2.2 - Plural rules <ul> <li><%= @post.comments.count %> comment(s)</li> </ul>
64. 2.2 - Plural rules <ul> <li><%= @post.comments.count %> comment<%= @post.comments.count > 1 ? "s" : "" %></li> </ul>
65. 2.2 - Plural rules <ul> <li> <%= t("posts.comments", count: @post.comments.count) %> </li> </ul>
66. 2.2 - Plural rules # en.y ml posts: comments: one: " % {count} comment" other: " % {count} comments"
67. 2.2 - Plural rules • English plurals have just 2 categories: one (singular); other (plural) • Other languages may have more or less! • 1 form for all numbers ( Chinese, Japanese, Korean) • Special form for 2 items ( Hebrew) • Special form for small or large groups ( Russian, Czech)
69. 💎 rails-i18n
70. 2.2 - Plural rules • rails-i18n provides implementations of the CLDR pluralization algorithm for many languages. • You still need to provide translations with the correct keys for each language you support.
71. 2.2 - Plural rules # en.y ml posts: comments: one: " % {count} comment" other: " % {count} comments" # ru.y ml posts: comments: one: " % {count} комментарий" few: " % {count} комментария" many: " % {count} комментариев" other: " % {count} комментариев"
72. 2.2 - Plural rules I18n. wi th_locale(:en) { I18n.t("posts.comments", count: 2) } #=> "2 comments" I18n. wi th_locale(:ru) { I18n.t("posts.comments", count: 2) } #=> "2 комментария"
73. 2.3 - List separators
74. 2.3 - List separators <ul> <li>Tags: <%= @post.tags.join(", ") %></li> </ul>
75. 2.3 - List separators <ul> <li> <%= t("posts.tags", tags: @post.tags.join(", ")) %> </li> </ul>
76. 2.3 - List separators • Languages may use different punctuation • e.g. U + 3001 “ɺ ” • Languages may have different rules about how punctuation is used • rails-i18n includes all this data!
77. 2.3 - List separators <ul> <li> <%= t("posts.tags", tags: @post.tags.join(", ")) %> </li> </ul>
78. 2.3 - List separators <ul> <li> <%= t("posts.tags", tags: @post.tags.to_sentence) %> </li> </ul>
79. 2.3 - List separators tags = % w (i18n l10n g11n) I18n. wi th_locale(:ja) { tags.to_sentence } #=> "i18nɺl10nɺg11n" I18n. wi th_locale(:en) { tags.to_sentence } #=> "i18n, l10n, and g11n"
80. Part III - Wrapping up
81. 3.1 - Recap • No hard-coded text or data formats • Machine-translated locale files • Data formats, plural rules, list separators based on CLDR standards • Just 4 gems (i18n, i18n-tasks, t w i tter_cldr, rails-i18n)
83. Source: Photo by Alex Knight on Unsplash Thank you! Good luck on your localization journey!
84. Links, credits, etc. • Stock images from Unsplash • Illustrations from Irasutoya • Gems mentioned: • https://github.com/glebm/i18n-tasks • https://github.com/twitter/twitter-cldr-rb • https://github.com/svenfuchs/rails-i18n