Better i18n support (language switching, localized content, etc.)

I've started working on better i18n on the i18n2 branch: https://github.com/VulcanJS/Vulcan/tree/i18n2

Overview

The main feature is the ability to localize user content, in other words support multiple languages for, e.g. a movie title or description.

Data Storage

Instead of storing the title field as a String, it will now be stored as an Object of the form {en: 'Die Hard', fr: 'Piège de cristal'}.

The cool thing with GraphQL is that the API can still return a String, meaning you wouldn't have to update any of your front-end code to support multiple languages.

Issues/Questions:

For existing content, should we migrate existing fields in place? Or add a new field (making the schema/forms more complex)?

Internationalizing a Field

For string fields, change type: String to type: getIntlString() in your schema.

Issues/Questions:

How do we handle resolveAs fields? Add a switch in the resolver based on context.locale?

Selecting a Locale

This is still a WIP, but there are currently two ways:

ask for title(locale: 'fr') in your GraphQL query.
set the locale header in your GraphQL query.

Issues/Questions:

How do we let users switch language?
- Based on domain (foo.com vs foo.fr)?
- Based on query string (foo.com/en vs foo.com/fr)?
How do we save a user's preferred language?
How do we detect the locale during the SSR process?
How do we pick the right locale when sending out emails? Based on which user the email is addressed to?

SmartForm

Works out of the box:

VulcanJS / Vulcan