Caching API responses in Astro - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to fetch data from an API and cache it using Astro's cache API.

Astro

const response = await fetch('[1]');
const data = await response.json();

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

A'https://api.example.com/data'

B'https://api.wrong.com/info'

C'/local/data.json'

D'http://invalid-url'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a local file path instead of an API URL.

Using an incorrect or invalid URL.

The correct API URL is 'https://api.example.com/data' to fetch the intended data.

2fill in blank

medium

Complete the code to cache the API response for 1 hour using Astro's cache API.

Astro

const cachedData = await Astro.cache('[1]', async () => {
  const response = await fetch('https://api.example.com/data');
  return await response.json();
}, { ttl: 3600 });

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

A'apiResponse'

B'cacheKey'

C'dataKey'

D'userData'

Attempts:

3 left

💡 Hint

Common Mistakes

Using an empty string or non-descriptive key.

Using a key that conflicts with other cached data.

The cache key 'cacheKey' is used to store and retrieve the cached API response.

3fill in blank

hard

Fix the error in the code to correctly cache the API response with a 30-minute expiration.

Astro

const data = await Astro.cache('apiData', async () => {
  const response = await fetch('https://api.example.com/data');
  return await response.json();
}, { ttl: [1] });

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

A1800

B3600

C300

D60

Attempts:

3 left

💡 Hint

Common Mistakes

Using ttl in minutes instead of seconds.

Using a ttl value too short or too long for the requirement.

The ttl (time to live) should be 1800 seconds for 30 minutes caching.

4fill in blank

hard

Fill both blanks to create a cache key using the API endpoint and user ID.

Astro

const cacheKey = '[1]' + '_' + [2];
const data = await Astro.cache(cacheKey, async () => {
  const response = await fetch('https://api.example.com/data');
  return await response.json();
}, { ttl: 600 });

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

A'apiData'

BuserId

C'cacheKey'

Duser.id

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong variable for user ID.

Not concatenating the key parts properly.

The cache key combines a string 'apiData' and the variable userId to uniquely identify cached data per user.

5fill in blank

hard

Fill all three blanks to fetch, cache, and handle errors gracefully.

Astro

try {
  const data = await Astro.cache([1], async () => {
    const response = await fetch([2]);
    if (!response.ok) throw new Error('Network error');
    return await response.json();
  }, { ttl: [3] });
} catch (error) {
  console.error(error);
}

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

A'userCache'

B'https://api.example.com/user'

C300

D'cacheKey'

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable instead of a string for cache key.

Using an incorrect API URL.

Setting ttl to an invalid value.

The cache key is 'cacheKey', the API URL is 'https://api.example.com/user', and ttl is 300 seconds for 5 minutes caching.

Practice

1. What is the main benefit of caching API responses in Astro?

easy

A. It speeds up the site by reusing previously fetched data

B. It increases the size of the API response

C. It makes the API slower to respond

D. It disables the API from updating

Solution

1. Step 1: Understand caching purpose

   Caching stores data from previous API calls to avoid fetching again.

2. Step 2: Identify benefit in Astro context

   Reusing cached data reduces load time and speeds up the site.

3. Final Answer:

   It speeds up the site by reusing previously fetched data -> Option A

4. Quick Check:

   Caching = Speed up site [OK]

Hint: Caching saves time by reusing data, not slowing down [OK]

Common Mistakes:

• Thinking caching makes API slower
• Confusing cache with data size increase
• Believing cache disables updates

2. Which syntax correctly sets cache revalidation time in Astro?

easy

A. const data = await fetch('https://api.example.com/data', { refresh: 60 });

B. const data = await fetch('https://api.example.com/data', { cacheTime: 60 });

C. const data = await fetch('https://api.example.com/data', { revalidate: 60 });

D. const data = await fetch('https://api.example.com/data', { updateAfter: 60 });

Solution

1. Step 1: Recall correct property name

   The correct property to control cache duration is revalidate.

2. Step 2: Match syntax with Astro docs

   The syntax uses { revalidate: 60 } inside fetch().

3. Final Answer:

   const data = await fetch('https://api.example.com/data', { revalidate: 60 }); -> Option C

4. Quick Check:

   Use revalidate property = const data = await fetch('https://api.example.com/data', { revalidate: 60 }); [OK]

Hint: Remember 'revalidate' sets cache time in seconds [OK]

Common Mistakes:

• Using wrong property names like cacheTime or refresh
• Forgetting to return an object
• Placing revalidate outside return

3. Given this code snippet in Astro:

const data = await fetch('https://api.example.com/data', { revalidate: 120 }).then(res => res.json());

What happens when a user visits the page after 3 minutes?

medium

A. The cached data is used without fetching again

B. The cache is cleared but data is not fetched

C. The page shows an error due to cache expiry

D. The data is fetched again from the API

Solution

1. Step 1: Understand revalidate timing

   The revalidate: 120 means cache lasts 120 seconds (2 minutes).

2. Step 2: Compare visit time with cache duration

   After 3 minutes (180 seconds), cache expired, so Astro fetches fresh data.

3. Final Answer:

   The data is fetched again from the API -> Option D

4. Quick Check:

   Cache expired after 120s, fetch again [OK]

Hint: If visit time > revalidate, data refetches [OK]

Common Mistakes:

• Assuming cache lasts forever
• Thinking cache clears but no fetch happens
• Confusing cache expiry with errors

4. Identify the error in this Astro caching code:

const data = await fetch('https://api.example.com/data').json();

medium

A. Missing await before .json() call

B. Incorrect property name 'revalidate'

C. fetch URL is invalid

D. Return statement missing props object

Solution

1. Step 1: Check fetch usage

   fetch returns a Promise; calling .json() needs to await the fetch first.

2. Step 2: Identify missing await

   Code calls fetch(...).json() without awaiting fetch, causing error.

3. Final Answer:

   Missing await before .json() call -> Option A

4. Quick Check:

   Await fetch before .json() [OK]

Hint: Always await fetch before calling .json() [OK]

Common Mistakes:

• Calling .json() directly on fetch without await
• Misnaming revalidate property
• Assuming fetch URL is wrong without checking

5. You want to cache API data in Astro but update it every hour. Which is the best way to set revalidate and why?

Options:
A) revalidate: 3600 to update every hour
B) revalidate: 60 to update every minute
C) revalidate: 0 to never cache
D) revalidate: -1 to disable caching

hard

A. revalidate: 60 to update every minute

B. revalidate: 3600 to update every hour

C. revalidate: 0 to never cache

D. revalidate: -1 to disable caching

Solution

1. Step 1: Understand revalidate meaning

   revalidate sets cache duration in seconds before refreshing data.

2. Step 2: Match desired update frequency

   To update every hour, set revalidate to 3600 seconds (60*60).

3. Step 3: Evaluate other options

   60 seconds updates too often, 0 disables caching, -1 is invalid.

4. Final Answer:

   revalidate: 3600 to update every hour -> Option B

5. Quick Check:

   1 hour = 3600 seconds revalidate [OK]

Hint: Set revalidate in seconds matching update frequency [OK]

Common Mistakes:

• Using too short revalidate causing frequent fetches
• Setting zero disables caching, not hourly update
• Negative values are invalid