next-translate-plugin breaks SSG in app router

[jakubjanousek]

What version of this package are you using?
2.6.0

What operating system, Node.js, and npm version?
node v20.4.0

What happened?
Once next-translate-plugin is used in next.config.js, pages cannot be statically generated in app router. There is nothing dynamic on the page or layout

module.exports = nextTranslate(); results in ┌ λ / 5.35 kB 85.8 kB
module.exports = {} results in ┌ ○ / 5.25 kB 85.6 kB

λ  (Server)  server-side renders at runtime (uses getInitialProps or getServerSideProps)
○  (Static)  automatically rendered as static HTML (uses no initial props)

i18n.json is

{
  "locales": ["en"],
  "defaultLocale": "en",
  "pages": {
    "*": ["common"]
  }
}

Any ideas why this is happening? You can check a minimal example at https://github.com/jakubjanousek/next-translate-ssg-issue

What did you expect to happen?
Pages without getServerSideProps will be statically generated with yarn build

Are you willing to submit a pull request to fix this bug?

[hensansi]

@aralroca I found the same issue recently when I started to migrate pages from pages to app. The first page I migrated was a static page so I simply used a export const dynamic = "force-static"; to deal with it.

Right now I started to migrate pages with translations and this is definitely a bigger issue given that any page I migrate will be dynamic because of next-translate. Are we missing something with the next-translate configuration?

Edit: I found the culprit, I tried to remove props.searchParams?.lang by hand and the problem was gone.

The usage of searchParams will make all the pages dynamic,
searchParams is a Dynamic API whose values cannot be known ahead of time. Using it will opt the page into dynamic rendering at request time.

I don't know what would be the alternative given that I'm not deep into the possible ramifications.

[hensansi]

@jakubjanousek @aralroca this is not a (final) solution but it displays where the problem is with the given repo,
hensansi/next-translate-ssg-issue@f1d1aad

   Creating an optimized production build  .Route (app)                              Size     First Load JS
┌ ○ /                                    5.35 kB        85.8 kB
└ ○ /_not-found                          884 B          81.3 kB
+ First Load JS shared by all            80.4 kB
  ├ chunks/738-70faf364855414b4.js       27.5 kB
  ├ chunks/fd9d1056-9c5946da9b5f2b9d.js  51 kB
  ├ chunks/main-app-ab8e99cf22ecae19.js  230 B
  └ chunks/webpack-396734a053f7bdbb.js   1.75 kB

[jakubjanousek]

good catch @hensansi, unfortunately I am not familiar with the reasons why searchParams is there

for now, we have removed next-translate-plugin and created custom useTranslation that just directly calls transCore with statically imported translation file

this allows us to have SSG by default while keeping all of the next-translate interface, but it is a very specific use case, since each of our languages is a single site that knows its locale at build time

[kkak10]

I'm having the same problem

@jakubjanousek Can I share your useTranslation implementation code?

[astorozhevsky]

for now, we have removed next-translate-plugin and created custom useTranslation that just directly calls transCore with statically imported translation file

@jakubjanousek Could you please share the code snippet or implementation details for this? It would be greatly helpful to understand how you integrated this into your setup.

[jakubjanousek]

Our situation is a bit specific that we have several deployment, but each has only a single translation. Therefore we are able to copy only the necessary translation before starting the server into current

a simplified version is something like this

import transCore from 'next-translate/transCore'
import currentLocale from 'locales/current/main.json'
import { Translate } from 'next-translate'

const lang = process.env.LOCALE || 'en'

const tWithoutNs = transCore({
  lang,
  config: {
    locales: [locale],
    defaultLocale: locale,
    defaultNS: 'main',
    loader: false,
    pages: {
      '*': ['main'],
    },
  },
  pluralRules: new Intl.PluralRules(lang),
  allNamespaces: { main: currentLocale as any },
})

export const getTranslate = () =>
  ({
    t: (key: string, query?: any, options = {}) => {
      return tWithoutNs(key, query, { ns: 'main', ...options })
    },
  } as { t: Translate })

[astorozhevsky]

Our situation is a bit specific that we have several deployment, but each has only a single translation. Therefore we are able to copy only the necessary translation before starting the server into current

a simplified version is something like this

import transCore from 'next-translate/transCore'
import currentLocale from 'locales/current/main.json'
import { Translate } from 'next-translate'

const lang = process.env.LOCALE || 'en'

const tWithoutNs = transCore({
  lang,
  config: {
    locales: [locale],
    defaultLocale: locale,
    defaultNS: 'main',
    loader: false,
    pages: {
      '*': ['main'],
    },
  },
  pluralRules: new Intl.PluralRules(lang),
  allNamespaces: { main: currentLocale as any },
})

export const getTranslate = () =>
  ({
    t: (key: string, query?: any, options = {}) => {
      return tWithoutNs(key, query, { ns: 'main', ...options })
    },
  } as { t: Translate })

@jakubjanousek Thank you so much for sharing your code and approach. In the end, we switched to using next-intl which solved our problems.