Code-first approach in NestJS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the Code-first approach in NestJS GraphQL?

It means you write your TypeScript classes and decorators first, then NestJS generates the GraphQL schema from your code automatically.

beginner

How do you define a GraphQL object type using the Code-first approach in NestJS?

You create a TypeScript class and decorate it with @ObjectType(), then decorate its fields with @Field() to expose them in the GraphQL schema.

beginner

Why is the Code-first approach helpful for beginners?

Because you work directly with familiar TypeScript code and decorators, avoiding manual schema writing and reducing errors.

beginner

Which decorator is used to mark a method as a GraphQL query in the Code-first approach?

The @Query() decorator is used on a method inside a resolver class to define a GraphQL query.

intermediate

How does NestJS generate the GraphQL schema in the Code-first approach?

NestJS scans your decorated classes and methods, then builds the schema automatically at runtime based on your code structure.

In NestJS Code-first approach, which decorator marks a class as a GraphQL object type?

A @Resolver()

B @ObjectType()

C @InputType()

D @Field()

The @ObjectType() decorator marks a class as a GraphQL object type in the Code-first approach.

Which decorator is used to expose a class property as a GraphQL field?

A @Field()

B @Query()

C @Mutation()

D @ObjectType()

The @Field() decorator exposes a class property as a GraphQL field.

What does the Code-first approach generate automatically from your code?

A Database migrations

B REST API endpoints

C GraphQL schema

D CSS styles

The Code-first approach automatically generates the GraphQL schema from your decorated TypeScript code.

Which decorator defines a GraphQL query method in a resolver?

A @Query()

B @Mutation()

C @Field()

D @ObjectType()

The @Query() decorator marks a method as a GraphQL query.

Why might developers prefer Code-first over Schema-first in NestJS?

A Because it requires writing schema files manually

B Because it only works with REST APIs

C Because it does not support GraphQL

D Because it uses decorators and TypeScript classes, making code easier to maintain

Code-first uses decorators and TypeScript classes, which many find easier to maintain and less error-prone.

Explain how the Code-first approach works in NestJS for building a GraphQL API.

Think about how your code becomes the schema.

List the main decorators used in the Code-first approach and their purpose.

Focus on decorators that define schema and operations.