GraphQL vs REST comparison - Practice Questions

Challenge - 5 Problems

🧠 Conceptual

intermediate

Key difference in data fetching between GraphQL and REST

Which statement best describes how GraphQL differs from REST in fetching data?

A Both GraphQL and REST require multiple endpoints to fetch different data types.

B REST allows clients to request exactly the data they need in a single query, while GraphQL requires multiple endpoints.

C GraphQL allows clients to request exactly the data they need in a single query, while REST often requires multiple endpoints.

D GraphQL does not support querying data, only mutations, unlike REST.

💡 Hint

Think about how many requests are needed to get related data in each approach.

GraphQL lets clients specify exactly what data they want in one request, reducing over-fetching and under-fetching. REST typically uses multiple endpoints, which may require several requests.

🧠 Conceptual

intermediate

Handling versioning in GraphQL vs REST

How is API versioning typically handled differently in GraphQL compared to REST?

A REST uses explicit version numbers in the URL, while GraphQL encourages evolving the schema without versioning.

B GraphQL uses explicit version numbers in the URL, while REST evolves the schema without versions.

C Both GraphQL and REST require version numbers in the URL for every change.

D Neither GraphQL nor REST support versioning.

💡 Hint

Consider how clients adapt to changes in each API style.

REST APIs often use version numbers in URLs to manage changes. GraphQL encourages evolving the schema by adding new fields and deprecating old ones without versioning.

❓ query_result

advanced

GraphQL query result shape

Given this GraphQL query:

{ user(id: "1") { name, posts { title } } }

What is the expected shape of the JSON response?

A {"data": {"name": "Alice", "posts": [{"title": "Post 1"}, {"title": "Post 2"}]}}

B {"data": {"user": {"name": "Alice", "posts": [{"title": "Post 1"}, {"title": "Post 2"}]}}}

C {"user": {"name": "Alice", "posts": [{"title": "Post 1"}, {"title": "Post 2"}]}}

D {"data": {"user": {"name": "Alice"}}}

💡 Hint

GraphQL responses always wrap data inside a 'data' key.

GraphQL responses wrap the requested data inside a 'data' object. The shape matches the query structure exactly.

📝 Syntax

advanced

Identify the syntax error in this GraphQL query

Which option contains a syntax error in the GraphQL query?

GraphQL

query { user(id: "1") { name posts { title } } }

A query { user(id: "1") { name, posts { title } } }

B } } } eltit { stsop ,eman { )"1" :di(resu { yreuq

C query { user(id: "1") { name posts { title } } }

D } } } eltit { stsop eman { )"1" :di(resu { yreuq

💡 Hint

Look for missing commas between fields.

GraphQL requires commas between fields in selection sets. Missing commas cause syntax errors.

❓ optimization

expert

Optimizing REST API calls compared to GraphQL

You have a REST API with endpoints /users and /posts. To get a user's name and their posts' titles, you must call both endpoints. How does GraphQL optimize this scenario?

A GraphQL duplicates data in each query to avoid multiple calls.

B GraphQL requires separate queries for user and posts, increasing network calls.

C GraphQL caches REST endpoints internally, so no optimization is needed.

D GraphQL allows fetching user name and posts titles in a single query, reducing network calls.

💡 Hint

Think about how many requests are needed in REST vs GraphQL for related data.

GraphQL lets clients request related data in one query, reducing the number of network calls compared to REST which requires multiple endpoints.

Practice

1. What is a key advantage of GraphQL compared to REST when fetching data?

easy

A. GraphQL does not support querying nested data.

B. GraphQL requires multiple URLs for different data resources.

C. GraphQL uses fixed data shapes for each resource.

D. GraphQL allows fetching exactly the data you want in a single request.

Solution

1. Step 1: Understand GraphQL data fetching

   GraphQL lets clients specify exactly what data they want in one request, avoiding over-fetching or under-fetching.

2. Step 2: Compare with REST approach

   REST typically requires multiple URLs and fixed data shapes, which can lead to multiple requests or extra data.

3. Final Answer:

   GraphQL allows fetching exactly the data you want in a single request. -> Option D

4. Quick Check:

   GraphQL = precise single-request data fetching [OK]

Hint: GraphQL = one request, exact data [OK]

Common Mistakes:

• Thinking GraphQL needs multiple URLs
• Believing GraphQL returns fixed data shapes
• Assuming GraphQL can't query nested data

2. Which of the following is the correct way to define a GraphQL query to get a user's name and email?

easy

A. { user: { name, email } }

B. query { user { name, email } }

C. SELECT name, email FROM user

D. GET /user/name,email

Solution

1. Step 1: Identify GraphQL query syntax

   GraphQL queries start with the keyword 'query' followed by the requested fields inside braces.

2. Step 2: Check each option

   query { user { name, email } } matches GraphQL syntax. GET /user/name,email is REST style URL. SELECT name, email FROM user is SQL. { user: { name, email } } is invalid JSON-like structure.

3. Final Answer:

   query { user { name, email } } -> Option B

4. Quick Check:

   GraphQL query syntax = query { user { name, email } } [OK]

Hint: GraphQL queries start with 'query' keyword [OK]

Common Mistakes:

• Using REST or SQL syntax instead of GraphQL
• Omitting the 'query' keyword
• Incorrect braces placement

3. Given this GraphQL query:

query { book(id: "1") { title author { name } } }

What data structure will the response most likely contain?

medium

A. {"data": {"book": {"title": "1984", "author": {"name": "George Orwell"}}}}

B. {"book": {"title": "1984", "author": "George Orwell"}}

C. {"data": {"book": {"title": "1984", "author": "George Orwell"}}}

D. {"data": {"book": {"title": "1984", "author": ["George Orwell"]}}}

Solution

1. Step 1: Understand GraphQL response format

   GraphQL responses wrap data inside a 'data' object, matching the query structure exactly.

2. Step 2: Match nested fields

   The query requests 'book' with 'title' and nested 'author' with 'name', so response must reflect nested objects.

3. Final Answer:

   {"data": {"book": {"title": "1984", "author": {"name": "George Orwell"}}}} -> Option A

4. Quick Check:

   GraphQL response = nested 'data' object [OK]

Hint: GraphQL responses wrap data inside 'data' key [OK]

Common Mistakes:

• Omitting the 'data' wrapper
• Flattening nested objects incorrectly
• Using arrays for single nested objects

4. Identify the error in this GraphQL query:

query { user(id: 5) { name, email } }

medium

A. The query keyword is missing.

B. The fields 'name' and 'email' should be inside parentheses.

C. The id value should be a string, so it needs quotes.

D. GraphQL does not support querying users by id.

Solution

1. Step 1: Check argument types in GraphQL

   GraphQL requires string arguments to be quoted. Here, id is likely a string and should be "5".

2. Step 2: Verify field syntax

   Fields 'name' and 'email' are correctly listed with commas, no parentheses needed.

3. Final Answer:

   The id value should be a string, so it needs quotes. -> Option C

4. Quick Check:

   String arguments need quotes in GraphQL [OK]

Hint: Quote string arguments in GraphQL queries [OK]

Common Mistakes:

• Leaving string arguments unquoted
• Adding parentheses around fields
• Assuming query keyword is optional

5. You want to design an API for a mobile app that needs flexible data fetching with minimal requests and efficient caching. Which approach is best and why?

hard

A. Use GraphQL because it allows clients to request exactly what they need in one request.

B. Use REST because it is simpler and caches well with fixed URLs.

C. Use REST because it supports nested queries better than GraphQL.

D. Use GraphQL because it requires multiple requests for different data.

Solution

1. Step 1: Analyze requirements for flexible data fetching and minimal requests

   GraphQL excels at letting clients specify exactly what data they want, reducing multiple requests.

2. Step 2: Consider caching and efficiency

   While REST is simpler and caches well, GraphQL's single-request flexibility suits mobile apps needing efficient data transfer.

3. Final Answer:

   Use GraphQL because it allows clients to request exactly what they need in one request. -> Option A

4. Quick Check:

   Flexible, minimal requests = GraphQL [OK]

Hint: Flexible single-request fetching = GraphQL [OK]

Common Mistakes:

• Choosing REST for flexibility over GraphQL
• Thinking GraphQL needs multiple requests
• Assuming REST handles nested queries better