Routing in Next.js

By Optimizely Education
Published: May 21, 2025
Rating 1 star 2 stars 3 stars 4 stars 5 stars

Average rating: 0 No reviews

Outline

Next.js uses a file-based routing system that's intuitive and powerful. Here's how to implement it in an Optimizely SaaS CMS project.

Basic File-Based Routing

Routes are defined by the file structure in the app directory:

app/
├── page.tsx         # Home page (/)
├── about/
│   └── page.tsx     # About page (/about)
└── blog/
    └── page.tsx     # Blog page (/blog)

Dynamic Routes for CMS Pages

For Optimizely CMS pages, use dynamic routes with square brackets [ ]:

app/
└── [locale]/
    ├── page.tsx           # Localized home page (/en, /sv, etc.)
    └── [slug]/
        └── page.tsx       # Dynamic CMS pages (/en/about, etc.)

Example Implementation

1. Localized Home Page:

// app/[locale]/page.tsx
export default async function LocalizedHome({ params }: { params: Promise<{ locale: string }> }) {
  const { locale } = await params;
  const { data } = await optimizely.GetStartPage({ locales: [locale] });
  return <h1>{data.StartPage.items[0].Title}</h1>;
}

2. Dynamic CMS Pages:

// app/[locale]/[slug]/page.tsx
export default async function CmsPage({ params }: { params: Promise<{ locale: string; slug: string }> }) {
  const { locale, slug } = await params;
  const { data } = await optimizely.GetPageByURL({ locales: [locale], slug: `/${slug}` });
  if (!data?.CMSPage?.items?.[0]) return notFound();
  return <h1>{data.CMSPage.items[0].Title}</h1>;
}

Route Groups

Next.js introduces the concept of Route Groups, which allow you to organize routes without affecting the URL structure.

For example:

app/
├── (marketing)/
│   ├── about/
│   │   └── page.tsx   # Still maps to /about
│   └── contact/
│       └── page.tsx   # Still maps to /contact
└── (shop)/
    ├── products/
    │   └── page.tsx   # Still maps to /products
    └── cart/
        └── page.tsx   # Still maps to /cart

Route groups are useful for:

Organizing routes without affecting the URL structure
Creating multiple root layouts
Grouping routes for better code organization

Key Takeaways

File structure in app/ defines routes
Use [brackets] for dynamic segments (e.g., [locale], [slug])
Params are now handled as Promises in page components
Route groups organize code without changing URLs