[Question] How can i get the id sent on mutation inside my custom validator

[pedrodalvy]

📚 Documentation

I'm using graphql and i need to create a validation for unique fields in the db, for example, the user's email.

When registering a new user, I just see if the email already exists in the database. The problem is in the user update, I need to know how to get the id sent in mutation to ignore it in the query.

I'm using the class-validator as in the example below:

Mutation to update user

mutation{
  updateUser(input:{ id:"1", update:{ email: "[email protected]" } })
  { 
    id
  }
}

DTO's

@InputType()
export class CreateUserInput {
  @Field()
  @IsEmail()
  @MyCustomIsUniqueValidator()
  email: string;
}

@InputType()
export class UpdateUserInput {
  @Field()
  @IsEmail()
  @MyCustomIsUniqueValidator()
  email: string;
}

Custom validator

@Injectable()
@ValidatorConstraint({ async: true })
export class MyCustomIsUniqueValidator implements ValidatorConstraintInterface {
  async validate(email: string, args: ValidationArguments): Promise<boolean> {
    const emailExists = await User.findOne({ where: { email } });

    // how to get the id sent on mutation?
    console.log(args)

    return !emailExists;
  }
}

Console output:

{
   targetName: 'MyCustomIsUniqueValidator',
   property: 'email',
   object: UpdateUserInput { email: '[email protected]' },
   value: '[email protected]',
   constraints: []
 }

How can i get the id sent on mutation inside my custom validator?

[impcyber]

Try to use args.object
https://github.com/typestack/class-validator/blob/6c501131d537c0ca608f651708a5c87cf1b5312a/src/validation/ValidationArguments.ts#L24

[pedrodalvy]

Thanks for your time @impcyber, but I've tried this way and it didn't work.

Using default update method from nestjs-query, the args.object only returns informations from the mutation "update" field, without the id.

As I still don't quite understand how nestjs-query works with the class-validator, I'm overriding the service class to do this validation.

[impcyber]

I think you should use @BeforeCreateHook and @BeforeUpdateHook in this case
https://doug-martin.github.io/nestjs-query/docs/graphql/hooks#hook-class
You can get id, input for create and update for update separately from instance property.

Here is an example: https://github.com/doug-martin/nestjs-query/blob/master/examples/hooks/src/hooks.ts#L25

And there is from my code:

import {
  BeforeCreateOneHook,
  CreateOneInputType,
  OperationGroup,
} from '@nestjs-query/query-graphql'
import { BadRequestException, Injectable } from '@nestjs/common'
import { ReturnModelType } from '@typegoose/typegoose'
import assert from 'assert'
import { AccessService } from 'nest-casl'
import { InjectModel } from 'nestjs-typegoose'
import { AccountInputDTO } from '../dto/account'
import { AccountEntity } from '../entities'
import { IAccountContext } from './../interfaces/account-payload.interface'

@Injectable()
export class AccountCreateHook<T>
  implements BeforeCreateOneHook<T, IAccountContext>
{
  public constructor(
    @InjectModel(AccountEntity)
    private readonly accountModel: ReturnModelType<typeof AccountEntity>,
    private readonly accessService: AccessService,
  ) {}

  public async run(
    instance: CreateOneInputType<T>,
    context: IAccountContext,
  ): Promise<CreateOneInputType<T>> {
    const { account } = context.req

    return this.accountModel
      .exists({
        email: (instance.input as unknown as AccountInputDTO).email,
      })
      .then((exists): CreateOneInputType<T> => {
        assert(!exists, new Error())

        const granted = this.accessService.hasAbility(
          account,
          OperationGroup.CREATE,
          instance.input,
        )

        assert(granted, new Error())

        return instance
      })
      .catch(() => {
        throw new BadRequestException()
      })
  }
}

[pedrodalvy]

This is a very interesting solution, I hadn't thought of using hooks for this. I'm sure it's going to be better than my solution.

Thank you for your help, @impcyber.

[magrinj]

In case anyone get here during search, inside args of class-validator the object key only give you the current objet being validated.
I've made a PR#2327 adding an instance key that give you access to the whole object, it's fixing this issue because you can access the id from it.

[magrinj]

BTW: The problem I'm facing now is for async custom validator, it seems if I'm editing the input inside the BeforeCreateOne hook, my servie doesn't receive the edited input.
If I change my custom validator to something sync it works fine.