[Solved] Given this controller method with a pipe bound at method level:@UsePipes(new ValidationPipe()) @Get(':id') getItem(@Param('id')... }What happens if the incoming 'id' parameter is not a valid number? | NestJS

NestJS - Pipes

Given this controller method with a pipe bound at method level:

@UsePipes(new ValidationPipe())
@Get(':id')
getItem(@Param('id') id: number) { return id; }

What happens if the incoming 'id' parameter is not a valid number?

AThe request is rejected with a validation error

BThe method returns the invalid 'id' string as is

CThe pipe is ignored and no validation occurs

DThe method throws a runtime exception

Step-by-Step Solution

Solution:

Step 1: Understand ValidationPipe behavior
ValidationPipe checks input and rejects requests if validation fails.
Step 2: Apply to method-level pipe binding
Since the pipe is bound at method level, it validates all parameters before method runs.
Final Answer:
The request is rejected with a validation error -> Option A
Quick Check:
ValidationPipe rejects invalid input = A [OK]

Quick Trick: ValidationPipe blocks invalid data before method runs [OK]

Common Mistakes:

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