Dynamic route parameters in Remix - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a dynamic route parameter in Remix.

Remix

export default function Post() {
  const params = useParams();
  return <div>Post ID: {params.[1]</div>;
}

Drag options to blanks, or click blank then click option'

Aid

BpostId

Cslug

Dparam

Attempts:

3 left

💡 Hint

Common Mistakes

Using a parameter name that does not match the file name.

Trying to access params without using useParams hook.

The dynamic route parameter is accessed via params.id when the route file is named $id.jsx.

2fill in blank

medium

Complete the code to fetch the dynamic parameter from the loader function.

Remix

export async function loader({ params }) {
  const postId = params.[1];
  return json({ postId });
}

Drag options to blanks, or click blank then click option'

Aslug

Bid

CpostId

Dparam

Attempts:

3 left

💡 Hint

Common Mistakes

Using a parameter name that does not match the route file.

Trying to destructure params incorrectly.

The loader receives the dynamic parameter as params.id if the route file is named $id.jsx.

3fill in blank

hard

Fix the error in the route file to correctly define a dynamic route parameter.

Remix

import { useParams } from '@remix-run/react';

export default function User() {
  const params = useParams();
  return <div>User: {params.[1]</div>;
}

// The file is named users.$userId.jsx

Drag options to blanks, or click blank then click option'

AuserId

Bid

Cuser

Dparam

Attempts:

3 left

💡 Hint

Common Mistakes

Using a generic 'id' instead of the specific parameter name.

Not importing useParams from Remix.

The dynamic parameter matches the file name segment $userId, so use params.userId.

4fill in blank

hard

Fill both blanks to create a loader that fetches data using the dynamic parameter and returns JSON.

Remix

export async function loader({ [1] }) {
  const id = [2].id;
  const data = await fetchDataById(id);
  return json(data);
}

Drag options to blanks, or click blank then click option'

Aparams

Brequest

Dcontext

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'request' instead of 'params' to get route parameters.

Trying to access id directly without params.

The loader receives an object with params. Use params.id to get the dynamic parameter.

5fill in blank

hard

Fill all three blanks to create a Remix route component that uses the loader data and dynamic parameter.

Remix

import { useLoaderData, useParams } from '@remix-run/react';

export default function Post() {
  const data = useLoaderData();
  const [1] = useParams();
  return (
    <main>
      <h1>Post ID: [2].id</h1>
      <p>{data.content}</p>
    </main>
  );
}

export async function loader({ [3] }) {
  const post = await getPostById([3].id);
  return json(post);
}

Drag options to blanks, or click blank then click option'

Aparams

Drequest

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for params in component and loader.

Trying to access id without params.

The dynamic parameter is accessed via params both in the component and loader.

Practice

1. What does a dynamic route parameter in Remix allow you to do?

easy

A. Create pages that change content based on the URL

B. Make the app load faster by caching pages

C. Automatically style pages with CSS

D. Prevent users from accessing certain pages

Solution

1. Step 1: Understand dynamic routes

   Dynamic routes let pages show different content depending on URL parts.

2. Step 2: Identify the purpose

   This means one page file can handle many URLs by reading parameters.

3. Final Answer:

   Create pages that change content based on the URL -> Option A

4. Quick Check:

   Dynamic routes = flexible pages [OK]

Hint: Dynamic routes change page content by URL parts [OK]

Common Mistakes:

• Thinking dynamic routes speed up loading
• Confusing dynamic routes with styling
• Believing dynamic routes block access

2. Which filename correctly defines a dynamic route parameter for a user ID in Remix?

easy

A. user.$id.jsx

B. userId$.jsx

C. $userId.jsx

D. user.$userId.jsx

Solution

1. Step 1: Recall Remix dynamic route syntax

   Dynamic parameters use a $ prefix in the filename, like $paramName.jsx.

2. Step 2: Match correct filename

   For user ID, $userId.jsx is correct; others have extra dots or misplaced $.

3. Final Answer:

   $userId.jsx -> Option C

4. Quick Check:

   Dynamic param filename = $paramName.jsx [OK]

Hint: Use $ before param name in filename for dynamic routes [OK]

Common Mistakes:

• Putting $ after the dot in filename
• Using multiple $ signs
• Naming file without $ for dynamic param

3. Given this Remix route file routes/$postId.jsx with code:

import { useParams } from '@remix-run/react';
export default function Post() {
  const params = useParams();
  return <div>Post ID: {params.postId}</div>;
}

What will be rendered when visiting URL /123?

medium

A. Post ID: postId

B. Post ID: 123

C. Post ID: undefined

D. Error: useParams not found

Solution

1. Step 1: Understand useParams behavior

   useParams() returns an object with keys matching dynamic route names and values from URL.

2. Step 2: Match URL to param

   URL /123 sets postId to '123', so params.postId is '123'.

3. Final Answer:

   Post ID: 123 -> Option B

4. Quick Check:

   useParams() returns URL param values [OK]

Hint: useParams() keys match $param names in filename [OK]

Common Mistakes:

• Expecting param name as string instead of value
• Forgetting to import useParams
• Assuming useParams returns undefined

4. What is wrong with this Remix route file named routes/$user.jsx? It contains:

import { useParams } from '@remix-run/react';
export default function User() {
  const { userId } = useParams();
  return <div>User: {userId}</div>;
}

medium

A. The filename parameter and useParams key do not match

B. useParams cannot be destructured

C. JSX must use parentheses around return

D. Dynamic route files cannot be named with $

Solution

1. Step 1: Check filename parameter name

   Filename uses $user.jsx, so param name is 'user'.

2. Step 2: Check useParams destructuring

   Code destructures 'userId' which does not exist in params; should use 'user'.

3. Final Answer:

   The filename parameter and useParams key do not match -> Option A

4. Quick Check:

   Param name in filename = key in useParams [OK]

Hint: Param name in filename and useParams must match exactly [OK]

Common Mistakes:

• Destructuring wrong param name
• Thinking useParams can't be destructured
• Believing $ in filename is invalid

5. You want to create a Remix route that shows a product page with a dynamic productId and also fetches product data server-side. Which filename and code snippet correctly use dynamic route parameters and server loader?

hard

A. routes/$productId.jsx withimport { useLoaderData, useParams } from '@remix-run/react';
export async function loader({ params }) {
return fetch(`https://api.example.com/products/${params.id}`);
}
export default function Product() {
const product = useLoaderData();
const { productId } = useParams();
return <div>Product {productId}: {product.name}</div>;
}

B. routes/product.$id.jsx withexport async function loader({ params }) {
return fetch(`https://api.example.com/products/${params.id}`);
}
export default function Product() {
const product = useLoaderData();
return <div>Product: {product.name}</div>;
}

C. routes/$productId.jsx withexport async function loader() {
return fetch('https://api.example.com/products');
}
export default function Product() {
const product = useLoaderData();
return <div>Product: {product.name}</div>;
}

D. routes/$productId.jsx withimport { useLoaderData } from '@remix-run/react';
export async function loader({ params }) {
return fetch(`https://api.example.com/products/${params.productId}`);
}
export default function Product() {
const product = useLoaderData();
return <div>Product: {product.id}</div>;
}

Solution

1. Step 1: Check filename for dynamic param

   Filename $productId.jsx correctly defines dynamic param 'productId'.

2. Step 2: Verify loader and component

   Loader uses params.productId to fetch product data, matching filename param. Component uses useLoaderData() and renders correctly.

3. Final Answer:

   routes/$productId.jsx with loader using params.productId -> Option D

4. Quick Check:

   Filename param = params key = loader fetch param [OK]

Hint: Match filename param, loader params, and useLoaderData usage [OK]

Common Mistakes:

• Mismatching param names in filename and loader
• Not using params in loader
• Ignoring useLoaderData for fetched data