NestJs Questions

Георгий Кузнецов

Score: 🔥 40

Intermediate

Took 4 minutes

Programming Framework

NestJs

90%

Questions Attempted

10 / 10

Correct Answers

Incorrect Answers

Points Earned

🔥 9

Question 1

What is a key advantage of using a message broker like RabbitMQ or Kafka for NestJS microservice communication?

Simplified database management
Improved error handling and retries
Reduced need for code testing
Automatic user interface generation

Explanation:

Message brokers introduce a robust layer for handling message delivery. If a service is down, the message is persisted and can be retried, enhancing fault tolerance.

Question 2

What is the role of the 'transform()' method within a custom Pipe in NestJS?

It defines the metadata associated with the Pipe.
It specifies how the Pipe should handle errors.
It contains the logic to transform the input data.
It determines if the Pipe should be applied globally.

Explanation:

The 'transform()' method is the core of a custom Pipe. This is where you write the code to manipulate, validate, or transform the input data before it reaches your route handler.

Question 3

In TypeORM, what is the purpose of an Entity?

To define database tables and their columns
To manage database connections
To handle HTTP requests
To define routes in a NestJS application

Explanation:

Entities in TypeORM represent database tables. They are classes decorated with @Entity(), and their properties correspond to columns in the table. This mapping allows TypeORM to synchronize your code with the database schema.

Question 4

How do you define a custom HTTP exception filter in NestJS?

By creating a class that implements the HttpException interface.
By using the @Catch() decorator without any arguments.
By creating a function and annotating it with the @ExceptionHandler() decorator.
By creating a class that implements the ExceptionFilter<T> interface and using the @Catch() decorator with the specific exception type.

Explanation:

To create a custom exception filter, you define a class that implements ExceptionFilter<T>, where T is the exception type you want to handle. You then use the @Catch(HttpExceptionType) decorator on the class, specifying the exception type to catch.

Question 5

In a NestJS microservice architecture, how do services typically communicate with each other asynchronously?

Direct method calls
Message queues
Shared memory
Database triggers

Explanation:

Message queues provide a decoupled way for services to send and receive messages asynchronously, enhancing reliability and fault tolerance.

Question 6

What is the primary function of a Pipe in NestJS?

To handle database queries and operations.
To transform input data into the desired format.
To define middleware for routing HTTP requests.
To manage dependency injection within the application.

Explanation:

Pipes in NestJS act as data transformers. They intercept incoming requests and can modify, validate, or transform data before it reaches the route handler.

Question 7

What is the purpose of the 'ParseIntPipe' in NestJS?

To convert a string value to a Boolean.
To parse an object into a JSON string.
To transform a numeric string into an integer.
To validate the data type of an input parameter.

Explanation:

The ParseIntPipe is specifically designed to take a string input and attempt to convert it into an integer. It's useful for handling route parameters or query strings that are expected to be numbers.

Question 8

How can you apply a transformation interceptor to a specific method in a controller in NestJS?

By using the @UseInterceptors() decorator at the method level
By registering the interceptor globally in the app.module.ts file
By extending the BaseController class and applying the interceptor in the constructor
By using the @Transform() decorator above the controller class

Explanation:

To apply a transformation interceptor to a specific method within a controller, you use the @UseInterceptors() decorator directly above the method definition. This ensures the interceptor is applied only to that specific method.

Question 9

What is a common way to implement Role-Based Access Control (RBAC) in NestJS Guards?

By directly embedding complex SQL queries within the Guard's canActivate method.
By using a library like Passport.js to offload all authentication and authorization logic.
By retrieving user roles from the database and checking if they match the roles required to access the protected route.
By defining access rules in a separate JSON file and parsing it within the Guard.

Explanation:

A common approach is to fetch the user's roles during authentication, store them (e.g., in the request object), and then access and compare them within your Guards to determine access rights.

Question 10

What is the main function of a transformation interceptor in NestJS?

To handle errors and exceptions thrown during request processing
To modify the incoming request or outgoing response data
To validate the structure and data types of incoming requests
To log request and response details for debugging purposes

Explanation:

Transformation interceptors in NestJS are designed to modify or transform the incoming request data before it reaches the route handler or the outgoing response data before it's sent back to the client.