Pipes, Guards & Interceptors — Series 3

Preview — 3 of 10 questions

What does this pipe do?

javascript

enum Status { Active = 'active', Archived = 'archived' }

@Get()
findAll(@Query('status', new ParseEnumPipe(Status)) status: Status) {}

AIt converts the string to the enum's numeric index

BIt checks the incoming value against the enum's members and rejects anything else with a 400, so the handler can rely on status being one of the declared values

CIt returns the enum's default member when the value is unrecognised

DIt only works with numeric enums

What does the client receive?

javascript

@Get(':id')
findOne(@Param('id', ParseIntPipe) id: number) {}
// GET /cats/abc

A200 with id set to NaN

B500, because the conversion throws inside the handler

C422 Unprocessable Entity

D400 Bad Request with a message naming the failed validation — the pipe throws BadRequestException, which the exception layer turns into a standard error response

What has to happen for the handler to run?

javascript

@UseGuards(AuthGuard, RolesGuard, QuotaGuard)
@Post() create() {}

AAll three must allow the request: guards run in declaration order and the first one to return false or throw stops the chain, so the remaining guards never execute

BAt least one must allow the request; guards are combined with OR

CThey run in parallel and the majority decides

DOnly the last guard's result is considered

Answer all 10 questions (7 more), see explanations for every answer, and track your score.