Rails i18n translations in Yaml: translation tool support

With Rails 2.2 the i18n API was introduced with a new method for translations.  Instead of embracing the venerable gettext which had been the previous standard, the Rails team invented a new way using Yaml files.  The result is a particularly graceful, flexible and very Rubylike way of specifying translations.  It also is much more reliable than gettext, which had many inscrutable issues with locales and caching, and sometimes caused people to get things in the wrong language.  So: bravo, great job.

But to do this, they specified their own translation format, the very flexible Yaml file. There are already a lot of formats floating around, and translation tool vendors and open-source translation developers have been working for a long time on conversion tools between them.  The Translate Toolkit and Pootle emerged from South Africa (a country which groans beneath the weight revels in the glory of eleven official languages) which provide an excellent web-based tool for collaboration, centered around gettext PO files.  However, poor little Pootle started a migration from Python to Django, and we all know how rewrites go.  [Halfway. Badly.]  But Translate Toolkit supported a lot of formats:

• moz2po - Mozilla .properties and .dtd converter. Works with Firefox and Thunderbird
• oo2po - OpenOffice.org SDF converter (See also oo2xliff).
• odf2xliff - Convert OpenDocument (ODF) documents to XLIFF and vice-versa.
• prop2po - Java property file (.properties) converter
• php2po - PHP localisable string arrays converter.
• sub2po - Converter for various subtitle files
• txt2po - Plain text to PO converter
• po2wordfast - Wordfast Translation Memory converter
• po2tmx - TMX (Translation Memory Exchange) converter
• pot2po - initialise PO Template files for translation
• csv2po - Comma Separated Value (CSV) converter. Useful for doing translations using a spreadsheet.
• csv2tbx - Create TBX (TermBase eXchange) files from Comma Separated Value (CSV) files
• html2po - HTML converter
• ical2po - iCalendar file converter
• ini2po - Windows INI file converter
• json2po - JSON file converter
• web2py2po - web2py translation to PO converter
• rc2po - Windows Resource .rc (C++ Resource Compiler) converter
• symb2po - Symbian-style translation to PO converter
• tiki2po - TikiWiki language.php converter
• ts2po - Qt Linguist .ts converter
• xliff2po - XLIFF (XML Localisation Interchange File Format) converter

In its heels, Google introduced the Google Translate Toolkit, which lets you use the Google Translate engine to suggest translations (based on its own databases or translation memories you provide).  It also does the core of what Pootle does: collaboration, access, but without crashing and flakiness, and it works with:

• AdWords Editor Archive (.aea)
• Android Resource (.xml)
• Application Resource Bundle (.arb)
• Chrome Extension (.json)
• GNU gettext (.po)
• HTML (.html)
• Microsoft Word (.doc)
• OpenDocument Text (.odt)
• Plain Text (.txt)
• Rich Text (.rtf)
• SubRip (.srt)
• SubViewer (.sub)

But neither of them supports Yaml files.  Unfortunately, tooling support libraries have not embraced this format in the intervening two and a half years.  I did find one solution: i18n-translators-tools which supports conversion between Yaml and gettext PO files, but it's somewhat idiosyncratic, and it turns out there's a good reason why there isn't a straightforward Yaml ←→ PO converter: the PO format is consists of name-value pairs with metadata, and the Yaml format is a tree.

English source Yaml file	Spanish Yaml file produced by i18n-translators-tools from a PO file
page_info:   sales/credit_notes:     date: "Date"     title:       default: "Sales Credit Note"       new: "New Sales Credit Note"	page_info:   sales/credit_notes:     date: "Fecha"     title:       default:         default: "Sales Credit Note"         translation: "Crédito de venta"       new:         default: "New Sales Credit Note"         translation: "New Sales Credit Note"

There are some interesting things going on here: the Spanish Yaml file provides fallbacks so untranslated strings don't come through as blank.  The intermediate gettext PO file keeps the tree structure in the msgctxt metadata, and looks like this:

msgctxt "page_info.fuji_sales/sales_credit_notes.title.default"
msgid "Sales Credit Note"
msgstr "Crédito de venta"

msgctxt "page_info.fuji_sales/sales_credit_notes.title.new"
msgid "New Sales Credit Note"
msgstr "New Sales Credit Note"

So it's possible to use Google Translate Toolkit to translate your Rails Yaml files, provided you use the i18n-translators-tools library to do the conversions, and configure your Rails applications to support fallbacks.