Nestjs - Unique Constraints Class-Validator Decorator

nestjs-unique-constraints-validator.ts

import {
    ValidatorConstraint,
    ValidatorConstraintInterface,
    ValidationArguments,
    registerDecorator,
    ValidationOptions,
} from 'class-validator';
import { DataSource } from 'typeorm';

@ValidatorConstraint({ async: true })
export class isUnique implements ValidatorConstraintInterface {
    constructor(private readonly dataSource: DataSource) { }

    async validate(value: any, args: ValidationArguments) {
        const [entityName, exceptField = null] = args.constraints;
        const [property] = args.property.split('.');
        const entity = this.dataSource.manager.getRepository(entityName);
        console.log('args', args);
        const result = await entity.findOne({ where: { [property]: value } });

        if (!result) return true;
        // except field
        if (!exceptField) return false;

        const exceptFieldValue = (args.object as any)[exceptField];
        if (!exceptFieldValue) return false;

        return result[exceptField] === exceptFieldValue;

    }

    defaultMessage(args: ValidationArguments) {
        const [entityName] = args.constraints;
        return `${args.property} alread exists in ${entityName}!`;
    }
}

export function Unique(
    entityName: string,
    exceptField: string = null,
    validationOptions?: ValidationOptions) {
    return function (object: unknown, propertyName: string) {
        registerDecorator({
            target: object.constructor,
            propertyName: propertyName,
            options: validationOptions,
            constraints: [entityName, exceptField],
            validator: isUnique,
        });
    };
}