Query parameters in NestJS - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are query parameters in a web request?

Query parameters are key-value pairs added to the end of a URL after a question mark (?). They are used to send extra data to the server, like filters or options.

beginner

How do you access query parameters in a NestJS controller?

You use the @Query() decorator in a controller method to get query parameters from the request URL.

beginner

Example: How to get a single query parameter named 'page' in NestJS?

Use @Query('page') page: string in the controller method parameters to get the 'page' query parameter value.

intermediate

What type of data does @Query() return if no parameter name is given?

@Query() returns an object containing all query parameters as key-value pairs.

intermediate

Why is it important to validate query parameters in NestJS?

Validating query parameters helps prevent errors and security issues by ensuring the data is the right type and format before using it.

In NestJS, which decorator is used to access query parameters?

A @Body()

B @Param()

C @Headers()

D @Query()

@Query() is the correct decorator to access query parameters in NestJS controllers.

What does @Query('id') return in a NestJS controller method?

A The URL path parameter 'id'

B All query parameters as an object

C The value of the 'id' query parameter

D The request body

@Query('id') extracts the value of the 'id' query parameter from the URL.

If a URL is /users?sort=asc&page=2, what does @Query() return?

A { sort: 'asc', page: '2' }

B ['sort', 'asc', 'page', '2']

C null

D Only the first query parameter

@Query() returns an object with all query parameters as key-value pairs.

Why should query parameters be validated in NestJS?

A To avoid errors and security risks

B To speed up the server

C To change the URL

D To encrypt data automatically

Validation ensures query parameters are safe and correct before use.

Which HTTP method commonly uses query parameters?

A POST

B GET

C PUT

D DELETE

GET requests often use query parameters to filter or sort data.

Explain how to retrieve and use query parameters in a NestJS controller.

Think about how the URL query string maps to controller method parameters.

Why is validating query parameters important in NestJS applications?

Consider what could happen if invalid data is used directly.