nestjs/nest · error · BadRequestException

Validation failed

Error message

Validation failed

What it means

Error "Validation failed" thrown in nestjs/nest.

Source

Thrown at sample/01-cats-app/src/common/pipes/parse-int.pipe.ts:13

import {
  ArgumentMetadata,
  BadRequestException,
  Injectable,
  PipeTransform,
} from '@nestjs/common';

@Injectable()
export class ParseIntPipe implements PipeTransform<string> {
  async transform(value: string, metadata: ArgumentMetadata) {
    const val = parseInt(value, 10);
    if (isNaN(val)) {
      throw new BadRequestException('Validation failed');
    }
    return val;
  }
}

View on GitHub (pinned to 6ec0e2783d)

Solutions

1. Send a numeric value for the :id route parameter; ParseIntPipe rejects non-numeric input.
2. Fix the client request URL (e.g. /cats/1 instead of /cats/abc).
3. If non-numeric ids are valid, replace ParseIntPipe with a custom pipe that handles them.

Example fix

// client: GET /cats/42  (not /cats/abc)
@Get(':id')
findOne(@Param('id', ParseIntPipe) id: number) {}

When it happens

Trigger: Thrown at sample/01-cats-app/src/common/pipes/parse-int.pipe.ts:13 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of nestjs/nest@6ec0e2783d (2026-08-03). Data as JSON: /data/errors/23a9a5eda7869329.json. Report an issue: GitHub.