Add support for internationalization.

[johnhooks]

What problem does this address?

There currently isn't any support for translating the notification messages.

What is your proposed solution?

Add a basic translation file to the project.

Requirements

• generate a POT file.

  Currently running the cli command results in an error.

  wp i18n make-pot ./includes languages/wp-features-notifications.pot

  CLI error output

  PHP Fatal error:  Uncaught TypeError: implode(): Argument #2 ($array) must be of type ?array, string given in     phar:///Users/johnhooks/.bin/wp/php/WP_CLI/DocParser.php:75
  Stack trace:
  #0 phar:///Users/johnhooks/.bin/wp/php/WP_CLI/DocParser.php(75): implode(Array, '\n')
  #1 phar:///Users/johnhooks/.bin/wp/php/WP_CLI/Dispatcher/CompositeCommand.php(32):     WP_CLI\DocParser->get_longdesc()
  #2 phar:///Users/johnhooks/.bin/wp/php/WP_CLI/Dispatcher/CommandFactory.php(113):     WP_CLI\Dispatcher\CompositeCommand->__construct(Object(WP_CLI\Dispatcher\RootCommand), 'cli', Object    (WP_CLI\DocParser))
  #3 phar:///Users/johnhooks/.bin/wp/php/WP_CLI/Dispatcher/CommandFactory.php(45):     WP_CLI\Dispatcher\CommandFactory::create_composite_command(Object(WP_CLI\Dispatcher\RootCommand), 'cli',     'CLI_Command')
  #4 phar:///Users/johnhooks/.bin/wp/php/class-wp-cli.php(481): WP_CLI\Dispatcher\CommandFactory::create('cli',     'CLI_Command', Object(WP_CLI\Dispatcher\RootCommand))
  #5 phar:///Users/johnhooks/.bin/wp/php/commands/cli.php(3): WP_CLI::add_command('cli', 'CLI_Command')
  #6 phar:///Users/johnhooks/.bin/wp/php/WP_CLI/Bootstrap/RegisterFrameworkCommands.php(32): include_once    ('phar:///Users/j...')
  #7 phar:///Users/johnhooks/.bin/wp/php/bootstrap.php(75): WP_CLI\Bootstrap\RegisterFrameworkCommands->process    (Object(WP_CLI\Bootstrap\BootstrapState))
  #8 phar:///Users/johnhooks/.bin/wp/php/wp-cli.php(23): WP_CLI\bootstrap()
  #9 phar:///Users/johnhooks/.bin/wp/php/boot-phar.php(8): include('phar:///Users/j...')
  #10 /Users/johnhooks/.bin/wp(4): include('phar:///Users/j...')
  #11 {main}
    thrown in phar:///Users/johnhooks/.bin/wp/php/WP_CLI/DocParser.php on line 75
  Fatal error: Uncaught TypeError: implode(): Argument #2 ($array) must be of type ?array, string given in     phar:///Users/johnhooks/.bin/wp/php/WP_CLI/DocParser.php:75
  Stack trace:
  #0 phar:///Users/johnhooks/.bin/wp/php/WP_CLI/DocParser.php(75): implode(Array, '\n')
  #1 phar:///Users/johnhooks/.bin/wp/php/WP_CLI/Dispatcher/CompositeCommand.php(32):     WP_CLI\DocParser->get_longdesc()
  #2 phar:///Users/johnhooks/.bin/wp/php/WP_CLI/Dispatcher/CommandFactory.php(113):     WP_CLI\Dispatcher\CompositeCommand->__construct(Object(WP_CLI\Dispatcher\RootCommand), 'cli', Object    (WP_CLI\DocParser))
  #3 phar:///Users/johnhooks/.bin/wp/php/WP_CLI/Dispatcher/CommandFactory.php(45):     WP_CLI\Dispatcher\CommandFactory::create_composite_command(Object(WP_CLI\Dispatcher\RootCommand), 'cli',     'CLI_Command')
  #4 phar:///Users/johnhooks/.bin/wp/php/class-wp-cli.php(481): WP_CLI\Dispatcher\CommandFactory::create('cli',     'CLI_Command', Object(WP_CLI\Dispatcher\RootCommand))
  #5 phar:///Users/johnhooks/.bin/wp/php/commands/cli.php(3): WP_CLI::add_command('cli', 'CLI_Command')
  #6 phar:///Users/johnhooks/.bin/wp/php/WP_CLI/Bootstrap/RegisterFrameworkCommands.php(32): include_once    ('phar:///Users/j...')
  #7 phar:///Users/johnhooks/.bin/wp/php/bootstrap.php(75): WP_CLI\Bootstrap\RegisterFrameworkCommands->process    (Object(WP_CLI\Bootstrap\BootstrapState))
  #8 phar:///Users/johnhooks/.bin/wp/php/wp-cli.php(23): WP_CLI\bootstrap()
  #9 phar:///Users/johnhooks/.bin/wp/php/boot-phar.php(8): include('phar:///Users/j...')
  #10 /Users/johnhooks/.bin/wp(4): include('phar:///Users/j...')
  #11 {main}
    thrown in phar:///Users/johnhooks/.bin/wp/php/WP_CLI/DocParser.php on line 75

• add translations for an initial set of messages.

[johnhooks]

@erikyo I don't have any experience with WordPress localization, do you know the basics so we can get started? Because as soon as we get the db test data filled we will want this in place so we can actually render notifications.

[erikyo]

This is one of the many nice things WordPress does for you, and you don't need anything else to apart adding the "languages" folder in your plugin and do this
https://codex.wordpress.org/I18n_for_WordPress_Developers#Loading_a_Text_Domain

[johnhooks]

@erikyo because of how we decided to do the notificaton messages with title_key and message_key, and channels have name_key and description_key, we need to manually add entries in order for them to be looked up by the translating functions. Does that make sense?

[johnhooks]

Summary of thoughts from Discussion #113.

I believe the translation of a notification has to happen when it is emitted and stored in the database for the following reasons:

• If the code that registers a translation key is removed (either because the plugin stops supporting it or the plugin is uninstalled) the data in the database is broken and the notification can no longer be rendered.
• Translation is a costly file system based operation. Storing a notification message translated, drastically reduces the number of times a message has to be translated. It would be done once, not on every query for the message.

[erikyo]

yes i agree 100%. Currently it seems the most viable and functional option.

If notifications are stored per user it is assumed that user knows the language he uses, so i don't see anything so disadvantageous in this proposal

[johnhooks]

Perhaps this system shouldn’t be trying to tackle translations. It should provide a way for plugins to emit notifications. Leave providing translations to the plugins or new developments into how internationalization works. They are very different problems.

It will be difficult to save actionable and possibly customizable messages in a format which can be dynamically rendered in another language, especially when depending on third party code that would be required to indefinitely remain on the system to render the notification.

We could provide an API to query the languages preferences the users subscribed to a channel, and handle linking the correct translated message to the appropriate users when a notification is emitted.