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@jpolvora
Last active Jul 24, 2019
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const debug = require('./debug.config')('app:router-wrapper', console)
const wrapMethod = function (router, method) {
if (typeof router[method] !== "function") return false;
const original = router[method].bind(router);
debug('patching method: %o', method)
router[method] = (...args) => {
if (args.length < 2) return original(...args);
//first param can be string or array of strings, need to check and slice before get the middlewares array
const ff = args.findIndex(x => typeof x === "function");
if (ff === 0) return original(wrapMiddleware(...args));
return original(args.slice(0, ff), wrapMiddleware(...args.slice(ff)))
}
}
const wrapMiddleware = (...args) => async (req, res, next) => {
try {
if (!Array.isArray(args)) throw new Error("args must be an array of middelwares")
const mids = args.slice();
if (mids.length === 0) {
debug('warn: empty pipeline')
return next();
}
const nxt = async (err) => {
if (err) {
debug('previous middlware returned error: %s', err)
return next(err)
}
if (mids.length === 0) {
debug('pipelind end')
return next()
}
const mid = mids.shift();
if (typeof mid === "function") {
debug('%s: args count: %s', mid.name, mid.length)
return await mid(req, res, nxt)
}
debug('warn: no function: %o', mid)
return nxt();
}
debug('init wrapped pipeline: %d mids', mids.length)
return await nxt();
}
catch (err) {
debug('catched error: %o', err)
return next(err);
}
}
const wrapRouter = (router) => {
if (router._patched) return router;
["GET", "HEAD", "POST", "PUT", "DELETE", "CONNECT", "OPTIONS", "TRACE", "PATCH"]
.forEach(method => wrapMethod(router, method.toLowerCase()))
router._patched = true;
return router;
}
const wrapRouterConstructor = () => {
const express = require('express')
const Router = express.Router;
express.Router = function () {
debug('instantiating new Router()')
const router = Router();
wrapRouter(router)
return router;
}
}
module.exports = {
wrapMiddleware,
wrapRouter,
wrapRouterConstructor,
wrapMethod
}
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