Link headers for navigation in Rest API - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this HTTP Link header parsing?

Given the HTTP Link header below, what is the value of the 'next' URL extracted?

Rest API

Link: <https://api.example.com/items?page=2>; rel="next", <https://api.example.com/items?page=5>; rel="last"

A https://api.example.com/items?page=1

B https://api.example.com/items?page=5

C https://api.example.com/items?page=2

D https://api.example.com/items?page=3

💡 Hint

Look for the rel="next" link in the header.

The Link header contains multiple URLs with rel attributes. The URL with rel="next" is the one for the next page, which is page=2.

🧠 Conceptual

intermediate

What is the purpose of the 'rel' attribute in Link headers?

In HTTP Link headers used for navigation, what does the 'rel' attribute specify?

A It sets the cache expiration time for the link.

B It specifies the HTTP method to use for the link.

C It indicates the content type of the linked resource.

D It defines the relationship type of the linked resource to the current resource.

💡 Hint

Think about how the client knows what the link means.

The 'rel' attribute describes the relationship between the current resource and the linked resource, such as 'next', 'prev', or 'last'.

🔧 Debug

advanced

Why does this Link header cause a parsing error?

Consider this Link header: Link: rel="next", ; rel="last" Why does it cause a parsing error?

A Because the first link is missing a semicolon before rel attribute.

B Because the rel attribute value is not capitalized.

C Because the URLs are not enclosed in quotes.

D Because the Link header must have only one URL.

💡 Hint

Check the syntax between the URL and the rel attribute.

Each link must separate the URL and its parameters with a semicolon. The first link misses the semicolon before rel="next".

🚀 Application

advanced

How to include multiple navigation links in a single Link header?

You want to provide 'first', 'prev', 'next', and 'last' navigation links in one HTTP Link header. Which is the correct format?

A Link: <url1>; rel="first", <url2>; rel="prev", <url3>; rel="next", <url4>; rel="last"

B Link: <url1> rel=first, <url2> rel=prev, <url3> rel=next, <url4> rel=last

C Link: <url1>; rel="first" <url2>; rel="prev" <url3>; rel="next" <url4>; rel="last"

D Link: rel="first" <url1>, rel="prev" <url2>, rel="next" <url3>, rel="last" <url4>

💡 Hint

Look for correct separators and syntax between links.

Multiple links in a Link header are separated by commas, and each link's parameters follow a semicolon after the URL.

❓ Predict Output

expert

What is the output of this Python code parsing Link headers?

Given the Python code below that parses an HTTP Link header, what is the output printed?

Rest API

link_header = '<https://api.example.com/items?page=3>; rel="next", <https://api.example.com/items?page=1>; rel="prev"'

links = {}
for part in link_header.split(','):
    url_part, rel_part = part.strip().split(';')
    url = url_part.strip()[1:-1]
    rel = rel_part.strip().split('=')[1].strip('"')
    links[rel] = url

print(links.get('prev'))

A https://api.example.com/items?page=3

B https://api.example.com/items?page=1

C None

D KeyError

💡 Hint

Check how the dictionary keys are assigned and what is printed.

The code splits the header by commas, extracts URLs and rel values, stores them in a dictionary, then prints the URL for 'prev'.