Dynamic routes with parameters in Astro - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a dynamic route file for a user profile page.

Astro

src/pages/users/[1].astro

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

Auser

B[id]

Cprofile

Dindex

Attempts:

3 left

💡 Hint

Common Mistakes

Using a fixed filename instead of a dynamic parameter.

Omitting the square brackets around the parameter.

In Astro, dynamic route parameters are defined using square brackets around the parameter name, like [id].

2fill in blank

medium

Complete the code to access the dynamic route parameter inside the Astro component.

Astro

const { params } = Astro; const userId = params.[1];

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

Aid

Bprofile

Cuser

Dparam

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different parameter name than defined in the filename.

Trying to access params with a wrong property.

The dynamic parameter name used in the filename (e.g., [id]) is accessed via params.id.

3fill in blank

hard

Fix the error in the code to correctly display the dynamic parameter in the page.

Astro

<h1>User ID: [1]</h1>

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

A{params.id}

B{user.id}

C{userId}

D{Astro.params.id}

Attempts:

3 left

💡 Hint

Common Mistakes

Using undefined variables like userId without declaring them.

Trying to access params directly without Astro.

In Astro components, dynamic parameters are accessed via Astro.params. So to display the ID, use {Astro.params.id}.

4fill in blank

hard

Fill both blanks to create a dynamic route that captures a post slug and displays it.

Astro

---
const { params } = Astro;
const slug = params.[1];
---
<h1>Post: [2]</h1>

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

Aslug

Bid

Dtitle

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing parameter names between id and slug.

Using undefined variables in the template.

The dynamic parameter is named slug in the filename, so access it with params.slug and display it with {slug}.

5fill in blank

hard

Fill all three blanks to create a nested dynamic route for category and product, and display both parameters.

Astro

---
const { params } = Astro;
const category = params.[1];
const product = params.[2];
---
<h1>Category: [3]</h1>
<p>Product: {product}</p>

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

Acategory

Bproduct

Ditem

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping parameter names or using wrong names.

Not displaying the correct variable in the template.

For nested dynamic routes like [category]/[product].astro, access parameters as params.category and params.product. Display the category with {category}.

Practice

1. What does a filename like [id].astro represent in Astro?

easy

A. A dynamic route that captures the id parameter from the URL

B. A static page named literally [id]

C. A component that cannot receive parameters

D. A special Astro configuration file

Solution

1. Step 1: Understand dynamic route syntax

   In Astro, square brackets in filenames like [id].astro define a dynamic route parameter named id.

2. Step 2: Recognize the purpose of the parameter

   This parameter captures part of the URL, allowing the page to change based on the URL segment.

3. Final Answer:

   A dynamic route that captures the id parameter from the URL -> Option A

4. Quick Check:

   Dynamic route = filename with [param] [OK]

Hint: Look for square brackets in filename for dynamic parameters [OK]

Common Mistakes:

• Thinking [id].astro is a static file
• Confusing parameter with component name
• Assuming parameters are optional by default

2. Which is the correct way to access a dynamic route parameter named slug inside an Astro component?

easy

A. Astro.query.slug

B. Astro.route.slug

C. Astro.params.slug

D. Astro.props.slug

Solution

1. Step 1: Recall Astro parameter access

   Astro provides dynamic route parameters inside the component via Astro.params.

2. Step 2: Use the parameter name as key

   To get the value of slug, use Astro.params.slug.

3. Final Answer:

   Astro.params.slug -> Option C

4. Quick Check:

   Access params with Astro.params.[name] [OK]

Hint: Use Astro.params to get dynamic route values [OK]

Common Mistakes:

• Using Astro.route or Astro.query instead of Astro.params
• Trying to access parameters via props
• Forgetting to use the exact parameter name

3. Given a file named src/pages/blog/[post].astro with this code snippet:

---
const postId = Astro.params.post;
---
Post ID: {postId}

What will be rendered when visiting /blog/42?

medium

A. Post ID: 42

B. Post ID: post

C. Post ID:

D. 404 Not Found

Solution

1. Step 1: Identify dynamic parameter value

   The URL /blog/42 matches the dynamic route [post].astro, so Astro.params.post is '42'.

2. Step 2: Render the parameter in the template

   The component outputs <h1>Post ID: {postId}</h1>, so it shows Post ID: 42.

3. Final Answer:

   <h1>Post ID: 42</h1> -> Option A

4. Quick Check:

   URL segment fills param = rendered value [OK]

Hint: URL segment replaces [param] and shows in Astro.params [OK]

Common Mistakes:

• Expecting literal 'post' instead of parameter value
• Assuming empty or missing parameter
• Confusing 404 with dynamic route handling

4. You have a dynamic route file named [user].astro but when visiting /john you get a runtime error: Cannot read property 'user' of undefined. What is the likely cause?

medium

A. Astro.params is only available in server components

B. You forgot to use Astro.params.user and accessed Astro.params directly

C. Dynamic routes cannot have parameters named 'user'

D. The filename should be {user}.astro instead of [user].astro

Solution

1. Step 1: Understand the error message

   The error says Cannot read property 'user' of undefined, meaning Astro.params is undefined or not accessed properly.

2. Step 2: Check parameter access syntax

   Accessing Astro.params.user is correct. If code tries to access Astro.params.user but Astro.params is undefined, it means Astro.params was not used or imported correctly.

3. Final Answer:

   You forgot to use Astro.params.user and accessed Astro.params directly -> Option B

4. Quick Check:

   Always use Astro.params.[param] to avoid undefined errors [OK]

Hint: Always access parameters via Astro.params.[name] [OK]

Common Mistakes:

• Using curly braces instead of square brackets in filename
• Assuming Astro.params is always defined globally
• Misnaming the parameter in code

5. You want to create a nested dynamic route in Astro to handle URLs like /products/electronics/123. Which file structure and parameter access is correct?

hard

A. Create src/pages/products/[category]/id.astro and access with Astro.params.id

B. Create src/pages/products/[category-id].astro and access with Astro.params['category-id']

C. Create src/pages/products/category/id.astro and access with Astro.params.category and Astro.params.id

D. Create src/pages/products/[category]/[id].astro and access with Astro.params.category and Astro.params.id

Solution

1. Step 1: Understand nested dynamic routes

   To match URLs like /products/electronics/123, you need nested folders with dynamic parameters: [category] and [id].

2. Step 2: Correct file structure and parameter access

   The correct structure is src/pages/products/[category]/[id].astro. Inside, access parameters as Astro.params.category and Astro.params.id.

3. Final Answer:

   Create src/pages/products/[category]/[id].astro and access with Astro.params.category and Astro.params.id -> Option D

4. Quick Check:

   Nested folders with [param] = nested params [OK]

Hint: Use nested folders with [param] for multi-level dynamic routes [OK]

Common Mistakes:

• Combining multiple params in one filename incorrectly
• Using static folder names instead of dynamic
• Accessing parameters that don't exist in the route