GenerateStaticParams for static paths in NextJS - Mini Project: Build & Apply

GenerateStaticParams for Static Paths in Next.js

📖 Scenario: You are building a simple blog website using Next.js. You want to create static pages for each blog post so that the pages load fast and work offline.To do this, you will use the generateStaticParams function to tell Next.js which blog post pages to create ahead of time.

🎯 Goal: Build a Next.js component that uses generateStaticParams to generate static paths for blog posts with IDs 1, 2, and 3.This will create static pages for each blog post at build time.

📋 What You'll Learn

Create a list of blog post IDs as strings

Create a generateStaticParams function that returns an array of objects with id properties

Create a React component that receives params and displays the blog post ID

Export the component as default and export generateStaticParams

💡 Why This Matters

🌍 Real World

Static site generation improves performance and SEO by pre-building pages for known paths.

💼 Career

Understanding generateStaticParams is essential for Next.js developers building fast, scalable websites.

1

Create the blog post IDs array

Create a constant array called postIds with the string values '1', '2', and '3'.

NextJS

# Create the array postIds with '1', '2', '3'
# Your code here

Hint

Use const postIds = ['1', '2', '3']; to create the array.

2

Create the generateStaticParams function

Create an async function called generateStaticParams that returns an array of objects. Each object should have an id property from the postIds array.

NextJS

const postIds = ['1', '2', '3'];

// Create async function generateStaticParams
// Your code here

Hint

Use postIds.map(id => ({ id })) to create the array of objects.

3

Create the blog post page component

Create a React functional component called PostPage that takes { params } as a prop and returns a <div> showing the text Post ID: followed by params.id.

NextJS

const postIds = ['1', '2', '3'];

export async function generateStaticParams() {
  return postIds.map(id => ({ id }));
}

// Create PostPage component
// Your code here

Hint

Use function PostPage({ params }) and return a div with the post ID.

4

Export the component and generateStaticParams

Ensure the PostPage component is exported as default and the generateStaticParams function is exported (already done). Confirm the full code includes the postIds array, the generateStaticParams function, and the PostPage component.

NextJS

const postIds = ['1', '2', '3'];

export async function generateStaticParams() {
  return postIds.map(id => ({ id }));
}

export default function PostPage({ params }) {
  return Post ID: {params.id};
}

// Confirm exports and full code

Hint

Check that all parts are exported and included in the code.

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 } }