Controllers

Question 1

What is the primary responsibility of controllers in an application?

Answer 1

Handling incoming requests and sending responses back to the client.

Question 2

What determines which controller will handle each request?

Answer 2

The routing mechanism.

Question 3

Can a controller handle multiple routes?

Answer 3

Yes, a controller often has multiple routes, and each route can perform a different action.

Question 4

What is used to create a basic controller?

Answer 4

Classes and decorators.

Question 5

What role do decorators play in creating a controller?

Answer 5

They link classes with the necessary metadata, allowing Nest to create a routing map.

Question 6

How can you quickly create a CRUD controller with built-in validation?

Answer 6

Use the CLI’s CRUD generator: nest g resource [name].

Question 7

What decorator is required to define a basic controller in NestJS?

Answer 7

@Controller()

The @Controller() decorator is essential for creating a controller in NestJS.

Question 8

What is the purpose of specifying an optional route path prefix in the @Controller() decorator?

Answer 8

To group related routes together and reduce repetitive code

This helps maintain cleaner and more organized code.

Question 9

What command is used to create a controller using the NestJS CLI?

Answer 9

$ nest g controller [name]

Replace [name] with the desired controller name.

Question 10

What does the @Get() decorator indicate in a NestJS controller?

Answer 10

It tells Nest to create a handler for a specific endpoint for HTTP GET requests

This decorator is used to define routes that respond to GET requests.

Question 11

How is the route path for a handler determined in NestJS?

Answer 11

By combining the optional prefix declared for the controller with any path specified in the method’s decorator

Example: If the controller prefix is ‘cats’ and the method decorator is @Get(‘breed’), the route will be GET /cats/breed.

Question 12

What is the default status code returned by NestJS for a successful response?

Answer 12

200

For POST requests, the default status code is 201.

Question 13

What happens when a request handler returns a JavaScript object or array?

Answer 13

It will automatically be serialized to JSON

This is part of the standard response handling in NestJS.

Question 14

What decorator allows the use of the library-specific response object in NestJS?

Answer 14

@Res()

This decorator injects the response object into the method handler.

Question 15

What must be set to use both standard and library-specific response handling in the same route?

Answer 15

Set the passthrough option to true in the @Res({ passthrough: true }) decorator

This allows partial use of both response handling methods.

Question 16

True or False: The method name in a NestJS controller must have specific significance.

Answer 16

False

The method name is arbitrary and does not affect the routing.

Question 17

What is the purpose of the request object in Nest?

Answer 17

It provides access to the client’s request details.

Question 18

How can you access the request object in a Nest handler?

Answer 18

By using the @Req() decorator in the handler’s signature.

Question 19

Which HTTP framework does Nest use by default for the request object?

Answer 19

Express

Question 20

What is the function of the @Get() decorator?

Answer 20

It defines a route handler for GET requests.

Question 21

What package needs to be installed to take advantage of express typings?

Answer 21

@types/express

Question 22

What properties does the request object contain?

Answer 22

Query string, parameters, HTTP headers, and body.

Question 23

True or False: You always need to manually access properties of the request object.

Answer 23

False

Question 24

What are some dedicated decorators available in Nest for accessing request properties?

Answer 24

• @Body()
• @Query()
• @Param()
• @Headers()
• @Ip()

Question 25

Fill in the blank: The @Response() decorator exposes the underlying ________ object interface.

Answer 25

native platform response

Question 26

What happens when you inject @Res() in a method handler?

Answer 26

You put Nest into Library-specific mode for that handler.

Question 27

What must you do if you use @Res() or @Response() in a handler?

Answer 27

Issue a response using the response object.

Question 28

What is the effect of not issuing a response when using @Res()?

Answer 28

The HTTP server will hang.

Question 29

What is the purpose of the @Session() decorator?

Answer 29

To access session data in the request.

Question 30

What does the @Param(key?: string) decorator correspond to?

Answer 30

req.params / req.params[key]

Question 31

What does @Body(key?: string) correspond to?

Answer 31

req.body / req.body[key]

Question 32

What is the use of the @Next() decorator?

Answer 32

To access the next middleware function.

Question 33

What does the @Query(key?: string) decorator correspond to?

Answer 33

req.query / req.query[key]

Question 34

What does the @Headers(name?: string) decorator allow you to access?

Answer 34

req.headers / req.headers[name]

Question 35

What is the purpose of the @Ip() decorator?

Answer 35

To access the IP address of the request.

Question 36

What does the @HostParam() decorator provide access to?

Answer 36

req.hosts

Question 37

What is the purpose of the POST handler in the CatsController?

Answer 37

To create new records, specifically to add a new cat ## Footnote The POST method is used to submit data to be processed to a specified resource.

Question 38

What does the @Get() decorator do in the CatsController?

Answer 38

It defines an endpoint that returns all cats ## Footnote The GET method is typically used to retrieve data from a server.

Question 39

List all the standard HTTP methods provided by Nest decorators.

Answer 39

* @Get() * @Post() * @Put() * @Delete() * @Patch() * @Options() * @Head() ## Footnote These decorators simplify the creation of RESTful APIs.

Question 40

What does the @All() decorator do?

Answer 40

It defines an endpoint that handles all HTTP methods ## Footnote Useful for endpoints that need to accept multiple types of requests.

Question 41

Fill in the blank: The action that adds a new cat is defined in the _______ method.

Answer 41

POST

Question 42

True or False: The CatsController can handle both creating and retrieving cat records.

Answer 42

True