However, for those users that need a simple solution and are willing to navigate a few hurdles, we do have a potential workaround utilizing content sub-folders.

Prerequisites

For this solution, we're going to leverage an advanced feature offered by Next.js: internationalized routing.

https://nextjs.org/docs/advanced-features/i18n-routing

While Next.js is used in our solution, other frameworks could be substituted as long as they offer similar features.

In this Guide

Updating the next.config.json to support i18n locales
Modifying getStaticPaths to build locale-aware paths
Modifying getStaticProps to include locale in the relativePath
Creating locale-ready Documents in the CMS

Update `next.config.js`

First off, we'll need to add the i18n section to the next.config.js along with both locales and a defaultLocale:

https://nextjs.org/docs/advanced-features/i18n-routing#getting-started

Note: defaultLocale provides a fallback for any unsupported locales.

/**
 * next.config.js
 */

module.exports = {
  ...
  i18n: {
    locales: ['en-US', 'fr', 'nl-NL'],
    defaultLocale: 'en-US'
  }
  ...
}

Modify `getStaticPaths()`

Given that we're adding i18n support to the post collection, we'll be updating getStaticPaths inside /pages/post/[filename].tsx.

/**
 * /pages/post/[filename].tsx
 */
import { client } from '../[pathToTina]/tina/__generated__/client'

// ...

// `locales` is provided to `getStaticPaths` and matches `locales` in the `config`
const getStaticPaths = async ({ locales }) => {
  const postConnection = await client.postConnection();
  const paths = [];

  // for each `post` document...
  postConnection.data.edges.map((post) => {
    // ensure a `path` is created for each `locale`
    locales.map((locale) => {
      paths.push({
        params: { filename: post.node._sys.filename },
        locale,
      });
    });
  });

  return {
    paths,
    fallback: true,
  }
}

Modify `getStaticProps()`

Next, we'll want to update getStaticProps to include locale as part of the relativePath.

/**
 * /pages/post/[filename].tsx
 */

// `locale` is provided alongside `params`
const getStaticProps = async({ params, locale }) {
  const tinaProps = await client.BlogPostQuery({
    // compose `relativePath` where `locale` is a sub-folder to the `post`
    relativePath: `${locale}/${params.filename}.mdx`,
  });

  return {
    props: {
      ...tinaProps
    }
  }
}

Create Locale-Ready Documents

Create Locale Document

Now, we'll venture into the CMS either through the Global Nav or directly via /admin.

For our example, we'll want to create three versions in our post collection by modifying the filename field to include each locale as a sub-folder:

en-US/hello-world for our "English (United States)" version
fr/hello-world for our "French" version
nl-NL/hello-world for our "Netherlands" version

Testing

Editing English

With our Documents created, we can confirm that the correct Document is loaded based on the user's locale by adding a console.log to getStaticProps:

/**
 * /pages/post/[filename].tsx
 */

// `locale` is provided alongside `params`
const getStaticProps = async({ params, locale }) {
  // console out the `locale`
  console.log('locale', locale)

  // compose `relativePath` where `locale` is a sub-folder to the `post`
  const relativePath = `${locale}/${params.filename}.mdx`

  const tinaProps = await client.BlogPostQuery({
    relativePath,
  });

  return {
    props: {
      ...tinaProps
    }
  }
}