[Solved] Given this pipe usage in a controller method:@UsePipes(new ValidationPipe())async create(@Body() data:... }What happens if the input data is missing a required field defined in CreateDto? | NestJS

NestJS - Pipes

Given this pipe usage in a controller method:

@UsePipes(new ValidationPipe())
async create(@Body() data: CreateDto) { return data; }

What happens if the input data is missing a required field defined in CreateDto?

AThe method receives the data with missing fields as undefined

BThe request is rejected with a validation error before reaching the method

CThe method throws an error when accessing missing fields

DThe missing fields are automatically filled with default values

Step-by-Step Solution

Solution:

Step 1: Understand ValidationPipe behavior
ValidationPipe checks input against DTO rules and rejects invalid data before method execution.
Step 2: Analyze what happens with missing required fields
Missing required fields cause validation failure, so the request is rejected early.
Final Answer:
The request is rejected with a validation error before reaching the method -> Option B
Quick Check:
ValidationPipe rejects invalid input early [OK]

Quick Trick: ValidationPipe stops invalid data before controller runs [OK]

Common Mistakes:

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