nextjs dynamic routes doesn't work with next-i18next - next.js

Question

I just added next-i18next in my nextjs project following the official guide and everything seemed to be in order, but when I change the language from default (Italian) to English and I go to the detail of an entity then I get 404. This happens only with the dynamic routes and only with the language that is not the default one.
I am going to show you more details.
My next-i18next.config.js file:
module.exports = {
i18n: {
defaultLocale: "it",
locales: ["it", "en"],
},
};
[id].tsx
//My NextPage component...
export async function getStaticPaths() {
const paths = await projects.find()?.map((_project) => ({
params: { id: _project.id + "" },
}));
return {
paths,
fallback: false,
};
}
export async function getStaticProps({
locale,
...rest
}: {
locale: string;
params: { id: string };
}) {
const project = await projects.findOne({id: rest.params.id})
const seo: Seo = {
//...
};
//This row is not the problem, since it persists even if I remove it. Also I am sure that the project exists.
if (!project?.id) return { notFound: true };
return {
props: {
...(await serverSideTranslations(locale, [
"common",
"footer",
"projects",
])),
seo,
project,
},
};
}
index.tsx (under projects folder)
const Projects: NextPage<Props> = ({ /*...*/ }) => {
//...
const router = useRouter();
return <button onClick={() =>
router.push({
pathname: `/projects/[slug]`,
query: { slug: project.slug },
})
}>Read more</button>
}
Also I get the error Error: The provided 'href' (/projects/[slug]) value is missing query values (slug) to be interpolated properly. when I try to change the language while I am in the detail of the project with the italian language set, but I think I did it right according to this doc. As I said before, instead, if I try to go into the dynamic route after having changed the language to "en" then I go to 404 page.
Do you have any suggestions to solve this problem?

Answer 1

I solved this by updating the mothod getStaticPaths to:
export async function getStaticPaths({ locales }: { locales: string[] }) {
const projects = getProjects({ locale: "it" });
const paths = projects.flatMap((_project) => {
return locales.map((locale) => {
return {
params: {
type: _project.slug,
slug: _project.slug,
},
locale: locale,
};
});
});
return {
paths,
fallback: true,
};
}
So there must be passed the locale into the paths.