Conditionally failing validation using class-validator

Question

Using conditional validation in the class-validation library and the example below, I want the validation to fail if the woodScrews property is given a value when the tool property is Tool.TapeMeasure. I wasn't really able to find anything that does that.

import { IsEnum, IsNumber, Min, ValidateIf } from 'class-validator'

export enum Tool {
  Drill = 'Drill',
  TapeMeasure = 'Tape Measure'
}

export class ToolBox {
  @IsEnum(Tool)
  public tool: Tool;

  @ValidateIf(toolBox => toolBox.tool === Tool.Drill)
  @IsNumber()
  @Min(5)
  public woodScrews?: number;
}

Juan Rambal · Accepted Answer · 2021-02-22 20:28:30Z

1

That method only works to ignore validations i.e with your dto, you validate that the class ToolBox has a property woodScrews of type number and with a minimun value of 5 only if the property Tool is equals to Drill otherwise you'll ignore the validations.

I'm not sure if you can solve this with class-validator but you can create some customs pipes and apply your own logic.

More info here: https://docs.nestjs.com/pipes

answered Feb 22, 2021 at 20:28

Juan Rambal

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1 Comment

Luke Over a year ago

Was afraid I'd have to implement my own, was hoping to get something out of the box. Thanks.

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