GraphQL Assessment | GraphQL vs REST

1

A mobile app and web app use the same backend. The mobile app needs user name and avatar. The web app needs name, avatar, email, and full address. With REST, what happens?

Both get exactly what they need You create two separate endpoints Mobile over-fetches or you maintain multiple endpoints REST automatically optimizes the response

2

You're building a social media feed. Each post needs author info, comments, and likes. The naive GraphQL resolver makes 1 + N + N + N database calls. What's the solution?

Use REST instead Limit the number of posts returned Use DataLoader to batch database calls Cache everything in memory

3

Your GraphQL API allows queries like: query { user { posts { comments { author { posts { comments { ... } } } } } } }. What's the security concern?

SQL injection Cross-site scripting Query complexity attacks can overload your server Authentication bypass

4

What's the key difference between a Query and a Mutation in GraphQL?

Queries are faster than mutations Mutations can return data, queries cannot Queries read data, mutations modify data (and mutations run sequentially) Queries require authentication, mutations don't

5

In a GraphQL schema, what does 'posts: [Post!]!' mean?

Optional array of optional posts Required array that may contain null posts Optional array of required posts Required array of required posts (never null, no null items)

6

Your GraphQL resolver returns: { id: '1', name: 'Sarah', email: 'sarah@test.com' }. The query only requests 'name'. What happens?

Error - resolver returns too much data GraphQL returns all three fields GraphQL automatically returns only { name: 'Sarah' } The extra fields are logged as warnings

7

What are the four arguments passed to every GraphQL resolver?

request, response, next, error query, schema, context, variables parent, args, context, info root, params, db, user

8

You need to cache GraphQL API responses at the CDN level. What's the challenge?

GraphQL responses are too large CDNs don't support GraphQL GraphQL uses POST requests which CDNs don't cache by default GraphQL schemas change too often

9

A team is building an internal dashboard that only they use. Data needs are stable and simple. They're debating GraphQL vs REST. What's your recommendation?

GraphQL - it's always better REST - simpler for stable, predictable needs with one client GraphQL - for the self-documenting schema Neither - use raw SQL

10

In DataLoader, why must the batch function return results in the same order as the input IDs?

For performance optimization DataLoader matches results to callers by array position To support pagination For better error messages

11

Your GraphQL mutation creates a user and needs to return the created user. What's the best practice?

Return just the user ID Return a boolean success flag Return the full created User object Return nothing and let client re-fetch

12

What problem does GraphQL Federation solve?

Authentication across services Database sharding Composing a unified schema from multiple GraphQL services Rate limiting

13

A resolver fetches user data from a REST microservice. The microservice is slow (500ms). What's the impact on a query requesting 10 users' data?

500ms total (parallel) 5000ms total (sequential) Depends on how you implement the resolver GraphQL automatically caches after first request

14

What's the purpose of GraphQL Input types?

To define query return types To group mutation arguments into reusable, validated structures To handle file uploads To define subscriptions

15

Your team adopted GraphQL 6 months ago. Frontend loves it but backend complains about complexity. What's likely happening?

GraphQL is fundamentally flawed N+1 problems, missing DataLoader, no complexity limits Frontend is using it wrong They need a different programming language

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