GenerateStaticParams for static paths in NextJS

Introduction

GenerateStaticParams helps Next.js know which pages to build ahead of time. It makes your site faster by creating pages before users visit.

You have a blog with fixed posts and want to build each post page before users visit.

You want to create product pages for an online store with known product IDs.

You have a list of user profiles that rarely change and want fast loading pages.

You want to improve SEO by pre-building pages with static content.

Syntax

NextJS

export async function generateStaticParams() {
  return [
    { id: '1' },
    { id: '2' },
    { id: '3' }
  ];
}

This function returns an array of objects. Each object represents a path parameter.

Next.js uses these to build static pages at build time.

Examples

Generates static paths for pages with slugs 'welcome' and 'about'.

NextJS

export async function generateStaticParams() {
  return [
    { slug: 'welcome' },
    { slug: 'about' }
  ];
}

Uses an array and maps it to create static params dynamically.

NextJS

export async function generateStaticParams() {
  const ids = ['a', 'b', 'c'];
  return ids.map(id => ({ id }));
}

Sample Program

This Next.js page uses generateStaticParams to pre-build pages for post IDs 1 and 2. When you visit /post/1 or /post/2, the page shows the post ID.

NextJS

import React from 'react';

export async function generateStaticParams() {
  return [
    { id: '1' },
    { id: '2' }
  ];
}

export default function Page({ params }) {
  return <h1>Post ID: {params.id}</h1>;
}

Important Notes

Make sure the keys in the returned objects match your dynamic route segment names.

generateStaticParams runs only at build time, so it cannot use request-specific data.

Summary

generateStaticParams tells Next.js which pages to build before users visit.

It returns an array of objects with route parameters.

This improves page speed and SEO for static content.

Practice

1. What is the main purpose of generateStaticParams in Next.js?

easy

A. To tell Next.js which dynamic routes to pre-render at build time

B. To fetch data on every user request

C. To handle client-side navigation between pages

D. To define API routes in Next.js

Solution

1. Step 1: Understand the role of generateStaticParams

   This function is used to specify dynamic route parameters for static generation.

2. Step 2: Compare with other Next.js features

   Unlike client-side navigation or API routes, generateStaticParams runs at build time to pre-build pages.

3. Final Answer:

   To tell Next.js which dynamic routes to pre-render at build time -> Option A

4. Quick Check:

   generateStaticParams = pre-render dynamic routes [OK]

Hint: Remember: generateStaticParams runs at build time for static pages [OK]

Common Mistakes:

• Confusing generateStaticParams with client-side data fetching
• Thinking it runs on every request
• Mixing it up with API route definitions

2. Which of the following is the correct syntax for generateStaticParams in a Next.js dynamic route file?

easy

A. export function generateStaticParams() { return ['1', '2']; }

B. export async function generateStaticParams() { return [{ id: '1' }, { id: '2' }]; }

C. export async function getStaticPaths() { return [{ params: { id: '1' } }]; }

D. export default function generateStaticParams() { return { paths: ['1', '2'] }; }

Solution

1. Step 1: Recall the correct return format

   generateStaticParams returns an array of objects with route parameters as keys.

2. Step 2: Check syntax correctness

   export async function generateStaticParams() { return [{ id: '1' }, { id: '2' }]; } correctly exports an async function returning [{ id: '1' }, { id: '2' }]. Others have wrong return types or use getStaticPaths.

3. Final Answer:

   export async function generateStaticParams() { return [{ id: '1' }, { id: '2' }]; } -> Option B

4. Quick Check:

   Return array of param objects = export async function generateStaticParams() { return [{ id: '1' }, { id: '2' }]; } [OK]

Hint: generateStaticParams returns array of objects with params keys [OK]

Common Mistakes:

• Using getStaticPaths instead of generateStaticParams
• Returning array of strings instead of objects
• Not exporting the function properly

3. Given this generateStaticParams function, what static paths will Next.js generate?

export async function generateStaticParams() {
  return [
    { slug: 'home' },
    { slug: 'about' },
    { slug: 'contact' }
  ];
}

medium

A. /home, /about, /contact

B. /slug/home, /slug/about, /slug/contact

C. /, /about, /contact

D. /home, /about, /contact, /blog

Solution

1. Step 1: Understand the returned params

   The function returns an array with slug keys: 'home', 'about', 'contact'.

2. Step 2: Map params to URLs

   Next.js uses these slugs as dynamic route parts, so paths are /home, /about, /contact.

3. Final Answer:

   /home, /about, /contact -> Option A

4. Quick Check:

   Params slug values = generated paths [OK]

Hint: Params keys map directly to URL segments in static paths [OK]

Common Mistakes:

• Adding extra path segments like /slug/
• Assuming root path / is included automatically
• Including paths not returned by generateStaticParams

4. Identify the error in this generateStaticParams function:

export async function generateStaticParams() {
  return [
    { id: 1 },
    { id: 2 },
    { id: 3 }
  ]
}

medium

A. There is no error; this is correct syntax

B. The function must return an object, not an array

C. The function must be named getStaticPaths instead

D. The id values should be strings, not numbers

Solution

1. Step 1: Check parameter types

   Route parameters in Next.js must be strings because URLs are strings.

2. Step 2: Identify type mismatch

   Here, id values are numbers (1, 2, 3), which can cause build errors or unexpected behavior.

3. Final Answer:

   The id values should be strings, not numbers -> Option D

4. Quick Check:

   Route params must be strings [OK]

Hint: Always use strings for route parameters in generateStaticParams [OK]

Common Mistakes:

• Returning numbers instead of strings for params
• Confusing generateStaticParams with getStaticPaths
• Returning object instead of array

5. You want to statically generate blog post pages with slugs from an API. Which generateStaticParams implementation correctly fetches slugs and returns them for static generation?

async function fetchSlugs() {
  return ['post-1', 'post-2', 'post-3'];
}

Choose the correct code:

hard

A. export async function generateStaticParams() {
const slugs = await fetchSlugs();
return slugs;
}

B. export async function generateStaticParams() {
const slugs = await fetchSlugs();
return { paths: slugs };
}

C. export async function generateStaticParams() {
const slugs = await fetchSlugs();
return slugs.map(slug => ({ slug }));
}

D. export async function generateStaticParams() {
const slugs = await fetchSlugs();
return slugs.map(slug => ({ params: { slug } }));
}

Solution

1. Step 1: Understand expected return format

   generateStaticParams expects an array of objects with route params keys directly, e.g. [{ slug: 'post-1' }].

2. Step 2: Analyze each option

   export async function generateStaticParams() { const slugs = await fetchSlugs(); return slugs.map(slug => ({ slug })); } returns slugs mapped to objects with slug keys correctly. export async function generateStaticParams() { const slugs = await fetchSlugs(); return { paths: slugs }; } returns an object, not array. export async function generateStaticParams() { const slugs = await fetchSlugs(); return slugs; } returns array of strings, not objects. export async function generateStaticParams() { const slugs = await fetchSlugs(); return slugs.map(slug => ({ params: { slug } })); } adds extra params key, which is incorrect for generateStaticParams.

3. Final Answer:

   export async function generateStaticParams() { const slugs = await fetchSlugs(); return slugs.map(slug => ({ slug })); } -> Option C

4. Quick Check:

   Return array of param objects without extra nesting [OK]

Hint: Map slugs to objects with keys matching route params [OK]

Common Mistakes:

• Returning object with paths key instead of array
• Returning array of strings instead of objects
• Adding extra nesting like { params: { slug } }