I'm completely new to node and it's frameworks Koa and express. I've a mongoose model called Drawing and a router module for that.
Problem is with express routers I was able the get the data from database using Drawing.find method but with Koa, control is not even going into Drawing.find. And I'm not able to get the data at all. Please find the following related code and help me understand the things better.
This is my router module
import * as Router from "koa-router";
import Drawing from "../../models/drawing";
function getRoutesForDrawing(): Router {
console.log("Inside getRoutes for drawing");
let route = new Router();
route.get("/drawing", function(context,next) {
console.log("Inside /drawing");
Drawing.find(function(err,drawings) {
console.log("Not gettig executed");
context.body = "Welcome";
});
//context.body = "Welcome";
});
}
export default getRoutesForDrawing();
And the model is
import mongoose = require("mongoose");
export interface IDrawing extends mongoose.Document {
drawingId:Number,
drawingName:String,
updatedOn:Date,
updatedBy:Number
};
export const DrawingSchema = new mongoose.Schema({
drawingId:Number,
drawingName:String,
updatedOn:Date,
updatedBy:Number
});
const Drawing = mongoose.model<IDrawing>('Drawing', DrawingSchema);
export default Drawing;
As you can see in my router module, the control is actually coming for /drawing and it's printing in console "Inside /drawing" but then control isn't coming to Drawing.find. I'm getting difficulty in understanding this.
It's a little bit hard to figure out what's going on because it looks like you have problems all over the place. Let me point out the things that stand out:
getRoutesForDrawing is declared to return a router and doesn't return anything
Koa routes are not like express. In particular they are not callback based. They take either generator functions (Koa 1.x) or async functions (Koa 2.x). You seem to expect that it's wanting a callback function which won't work. Assuming koa 2.x, its router.get('/drawing', async(context) => {...});
Assuming koa 2.x, you need to await the result of the mongoose methods, e.g. context.body = await Drawing.find({})
Related
I want to reuse all my servise and controllers and I was achieving this with extending class.
I'm calling the class of Controller and service all the way up from a router.
everything looks fine while creating instance of class,
but when I send request to sign in route it says there is no this.servise or this.dto which is i passed to the constructor while creating this instance of object
import express from "express";
const router = express.Router();
import UserController from "../../controllers/user.controller";
import UserService from "../../services/user.service.js";
import {UserDto} from "../../dtos/user.dto.js";
import User from "../../models/User.js";
const userService = new UserService(User);
console.log(userService, UserDto); // successfully logged
const userController = new UserController(userService, UserDto);
console.log(userController); // successfully logged
router.post('/signup', userController.signup);
router.post('/signin', userController.signIn);
router.post('/signout', userController.signOut);
router.get('/all', userController.getAll);
router.route("/:id")
.get(userController.get)
.post(userController.create)
.patch(userController.update)
.delete(userController.delete);
export default router;
export default class UserController extends MainController {
async signIn(req, res) {
try {
const {email, password} = req.body;//await this.dto.login(req.body);
const result = await this.service.signIn(email, password); // TypeError: Cannot read properties of undefined (reading 'service')
return res.status(201).json({message: "successfully signed in", token: result.token, user: this.dto.output(result.user)});
}
catch(err){
sendError(res, err);
}
}
I've reviewed my knowledge of how nodejs modules work, but I can't figure out what the problem is.
Who can explain me this situation, please!?
Thank you in advance!
You forgot to use .bind() when passing the references to the methods to the Express router. So who knows what the value of this will be when Express tries to call them (in JS, this doesn't work like other variable names, it doesn't use lexical scoping, what the value will be depends on the calling code).
Change your code to e.g.
router.post('/signup', userController.signup.bind(userController));
This will ensure that this is set to your userController object when the function gets called (bind() is a method available on all function objects that returns a new function with a fixed this value).
As far as I can understand, Clean Architecture/DDD states that your use cases can be triggered by anything, let it be a HTTP request or GUI, correct?
I am trying to emulate that, but I am not really sure if I am doing it correctly.
Inside my infrastructure folder, I have routers. For example:
import express from 'express'
import UserController from '../controllers/user_controller.js'
import ExpressRouterAdapter from './ExpressRouterAdapter.js'
export default function UsersRouter () {
const router = express.Router()
router.route('/:username').get(ExpressRouterAdapter.adapt(UserController.getUser))
return router
}
(ExpressRouterAdapter is just an adapter that transforms Express requests into a simple httpRequest JS object)
And here is my GetUser controller:
export class GetUser {
constructor ({ FindUserService }) {
this.findUser = FindUserService
}
async handle (httpRequest = {}) {
try {
const { username } = httpRequest.params
if (!username) {
return {
statusCode: 400,
body: 'Missing username parameter.'
}
}
const user = await this.findUser.execute(username)
// ...
I have a few questions:
Should I even have controllers? Should the Router direct it to the use-case/service directly?
^^ The reason I ask that is because my controllers are really HTTP centered. For example some of them are called: PostUser, GetUser, DeleteUser. So I am guessing they should be inside the infrastructure folder, right?
I am guessing that controllers are ONLY used if your delivery mechanism is a web app, right?
You're right. There's nothing really to do with DDD because DDD is about contexts and language, but for clean architecture and ports and adapters that's the correct thought.
Normally, you would have the structure like this:
So, your application exposes an API that represents a port and you can connect different edge components that implement a physical delivery protocol of different kinds to talk to your application.
I have an existing Node.js/Express app which connects to 2 separate databases, it has a MySQL DB for all the relational and a MongoDB store for the non-relational vertical data.
It uses Sequelize and Mongoose and works absolutely swimmingly.
I've been looking at Next.js today and I'm pretty impressed, one of my pet peeves with React is actually how much bootstrapping there is and how much code it takes to achieve something simple. Next.js seems to solve some of those issues for me, so I'm willing to embrace it.
First issue - Is it possible to connect Next.js to existing DB's and read their objects directly in the view?
e.g. ./server.js:
const mongoDb = mongoose.connect(configDB.url); // MongoDB connection
const models = require('./models'); // Sequelize connection
app.prepare().then(() => {
server.use((req, res, next) => {
req.mongodb = mongoDb
req.mysqldb = models
// Logging req.mysqldb/req.mongodb at this point gives the correct result.
next()
});
server.get('*', (req, res) => {
return handle(req, res)
})
})
./pages/index.js:
Index.getInitialProps = async function(req) {
console.log(req.mongodb);
console.log(req.mysqldb)
// Example of what I want: req.mysqldb.users.findAll()....... to populate collection for this view
}
When the console statements are executed in the index.js page, they are logged as undefined.
Ideally I want to use the objects/ORM layer directly in the next.js templates, I do not want to have to call my own API internally, it seems like a huge waste of resources!
Any help, greatly appreciated.
Just for future reference. getInitialProps gets passed in an object with one of the keys being req. So you're meant to do something like the following instead
// add the curly braces around req
Index.getInitialProps = async function({ req }) {
// code
}
This is known as Function Parameter Destructuring and was introduced in ES6. What this accomplishes is similar to the following code
Index.getInitialProps = async function(_ref) {
var req = _ref.req;
}
Meaning, it takes the value of req of the object that gets passed and uses that value.
Well apparently by the time the request gets to the template it has changed a bit! Namely, it is nested within another request object.
req.req.mongodb and req.req.mysqldb both work fine :).
I have two files, one of them is the app.js and the otherone is api.js.
In the first file I have :
app.use(setHeader)
app.use(api.routes())
app.use(api.allowedMethods())
And in api.js I have:
import KoaRouter from 'koa-router';
const api = new Router();
//Validatekey
const validateKey = async (ctx, next) => {
const { authorization } = ctx.request.headers;
console.log(authorization);
if (authorization !== ctx.state.authorizationHeader) {
return ctx.throw(401);
}
await next();
}
api.get('/pets', validateKey, pets.list);
When I run the project a error message is throw: Router is not defined.
But If I write both files together, the application go fine.
Anybody knows the problem?
I have solved with var Router = require('koa-router')
The import is currently not implemented in nodejs, neither is it supported in the latest ES2015(ES6).
You will need to use a transpiler like Babel to use import in code.I advice that avoid transpiler as it cause performance issues on production just go with require and it will work.
Obviously Nodejs does not support import / export syntax and using require will solve your problem.
However it is possible to make import work on Node.js by using babel transformers.
Look the following answer for more information https://stackoverflow.com/a/37601577/972240
I have such router:
exports.read = (req,res) ->
// do stuff with DB
res.status(200).send
data:data
Now how can I use this router inside another router, call it exports.wrapper? I wnat to avoid having to rewrite my DB requests again and again. Is this approach that I have in mind recommended?
I would not recommend attempting to wrap routers inside each other.
It's recommended in Express 4 to use Express's router object like so:
// router.js
var myRouter = express.Router();
myRouter.route('/read', myController.readMethod);
Then in your controller you would handle the request and end with the result call:
// myController.js
exports.readMethod = function(req, res) {
var data = readFromDB(req.params);
res.send('read method renders', data);
}
exports.readMethod2 = function(req, res) {
var data = readFromDB(req.params);
res.send('read method 2 renders', data);
}
function readFromDB(params) {
// make a call to the DB (maybe via a model)
// return some data
}
Hope that helps
edit
Additionally, I would recommend wrapping your DB calls in a model, to abstract them away from your router or controller logic. For a reference of a well organised Express App that uses MVC checkout this Yeoman generator - https://github.com/ngenerio/generator-express-simple
second edit
In my very brief example externalising the readFromDB method to a model makes this function moot, if all it's doing is getting data from the DB put it in a model.