NestJS, GraphQL, class-validator - access request object inside validate method

Question

I have a custom class-validator rule:

import { Injectable } from "@nestjs/common";
import { ValidatorConstraint, ValidatorConstraintInterface, ValidationArguments } from "class-validator";

@ValidatorConstraint({ name: "Foo", async: true })
@Injectable()
export class FooRule implements ValidatorConstraintInterface {    
    async validate(value: unknown, args: ValidationArguments) {
        // how to access request object from here?
    }
    
    defaultMessage(args: ValidationArguments) {
        return "NOT OK.";
    }
}

How do I access the request object inside the validate() method?

Answer 1

I ended up using a custom interceptor:

import { Injectable, NestInterceptor, CallHandler, ExecutionContext } from "@nestjs/common";
import { GqlExecutionContext } from "@nestjs/graphql";
import { ForbiddenError } from "apollo-server-core";
import { Observable } from "rxjs";

@Injectable()
export class FooInterceptor implements NestInterceptor {
    intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
        // get gql execution context from http one
        const gqlCtx = GqlExecutionContext.create(context);

        // holds data passed in a gql input
        const args: unknown[] = gqlCtx.getArgs();

        // req object (can be used to obtain jwt payload)
        const req = gqlCtx.getContext().req;

        // validation logic here
        const validationPassed = true;

        if (validationPassed) {
            // invoke the route handler method 
            return next.handle();
        }

        // will be caught by nest exceptions layer
        throw new ForbiddenError("Not allowed.");
    }
}