Express + Joi + Typescript validation middleware

express-joi-typescript-validate-middleware.ts

 app.get("/some-endpoint", validate({...}), (req, res, next) => {});

validate.ts

import * as joi from 'joi';
import { Request, Response, NextFunction } from 'express';

export interface IValidation {
    options?: IValidationOptions;
    body?: joi.SchemaLike;
    headers?: joi.SchemaLike;
    query?: joi.SchemaLike;
    cookies?: joi.SchemaLike;
    params?: joi.SchemaLike;
}

export interface IValidationOptions {
    allowUnknownBody?: boolean;
    allowUnknownQuery?: boolean;
    allowUnknownHeaders?: boolean;
    allowUnknownParams?: boolean;
    allowUnknownCookies?: boolean;
    joiOptions?: joi.ValidationOptions;
}

const props = ['body', 'query', 'headers', 'params', 'cookies'];

export const validate = (settings: IValidation) => {

    let errors = [];
    settings.options = settings.options || {};

    return (req: Request, res: Response, next: NextFunction) => {

        for (const p of props) {
            if (settings.hasOwnProperty(p)) {
                const options = settings.options.hasOwnProperty('joiOptions') ? settings.options.joiOptions : {};
                const name = `allowUnknown${p[0].toUpperCase()}${p.slice(1)}`;
                options.allowUnknown = settings.options.hasOwnProperty(name) ? settings.options[name] : true;

                const result = joi.validate(req[p], settings[p], options);

                if (result.hasOwnProperty('error') && result.error) {
                    errors = errors.concat(result.error.details);
                }

            }
        }

        if (errors.length) {
            return next({
                isJoi: true,
                errors: errors,
            });
        }

        next();
    };

};