TOPIC OVERVIEW

NestJS/GraphQL

Let clients request exactly the data they need instead of creating a separate endpoint for every response shape.

15 QuestionsAdvancedMedium Priority ~12 min read

GraphQL provides an alternative to traditional REST APIs where clients describe the data they need through queries. Instead of the server deciding the exact response shape for every endpoint, the GraphQL schema defines what data can be requested.

NestJS supports GraphQL through decorators, resolvers, schemas, and providers. Understanding how these pieces connect helps you build APIs where clients can request related data efficiently while keeping the server's data model and business logic organized.

What you'll walk away knowing

How GraphQL differs from REST

How schemas, queries, mutations, and resolvers work

How NestJS integrates GraphQL into an application

How to handle authentication and data access in GraphQL

1How do you define a GraphQL mutation in NestJS and what input type conventions should you follow?Intermediate 2How do you implement a DataLoader in NestJS and scope it correctly per request?Intermediate 3How do you implement query complexity analysis to prevent expensive GraphQL queries in NestJS?Advanced 4How do you add authorization guards to GraphQL resolvers in NestJS?Intermediate 5How do you pass arguments to a GraphQL query and validate them using @Args and input types in NestJS?Intermediate 6What is a GraphQL subscription and how do you enable it in NestJS?Intermediate 7How do you handle DataLoader cache invalidation and avoid serving stale data in NestJS?Advanced 8How do you test a NestJS GraphQL resolver with TestingModule?Intermediate 9What is the difference between code-first and schema-first approaches in NestJS GraphQL?Intermediate 10What are field resolvers in NestJS GraphQL and when do you use them instead of fetching all data in the root query?Intermediate 11How do you filter subscription events so each client only receives events relevant to them in NestJS?Intermediate 12How do you access the GraphQL context including the authenticated user inside a resolver in NestJS?Intermediate 13How do you scale GraphQL subscriptions across multiple NestJS instances?Advanced 14How do you handle GraphQL errors and return partial results for mutations in NestJS?Intermediate 15How do you define a GraphQL object type, enum, and union in code-first NestJS?Intermediate 16How do you implement and use a custom GraphQL scalar type in NestJS?Intermediate 17What is a resolver in NestJS GraphQL and how do you define a root query resolver?Intermediate 18How do you implement cursor-based pagination in NestJS GraphQL using the Relay Connection spec?Intermediate 19How do you bootstrap a NestJS GraphQL application in code-first mode?Intermediate 20How do you implement schema stitching or federation for a micro-frontend GraphQL architecture in NestJS?Advanced 21What is the difference between @ObjectType() and @InputType() in NestJS GraphQL and why can't you reuse the same class for both?Intermediate 22What is the N+1 problem in GraphQL and how does DataLoader solve it?Intermediate 23How do you implement a subscription using PubSub in NestJS GraphQL?Intermediate 24How does NestJS schema-first approach differ in setup and when would you choose it over code-first?Intermediate 25How do you make a DataLoader available in the GraphQL context so every resolver can access it in NestJS?Intermediate

All Topics

1

Dependency Injection

2

Request Lifecycle

Exception Handling

3

4

Database and ORM

5

Authentication and Authorization

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