parse-positive-int.pipe.ts

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

@Injectable()
export class ParsePositiveIntPipe implements PipeTransform<any, number | undefined | null> {
  transform(value) {
    if (value === null || value === undefined) {
      return value
    }

    const n = parseInt(value)
    if (isNaN(n) || n <= 0) {
      throw new BadRequestException()
    }

    return n
  }
}