Why does the following code not work
const {express} = require('express');
const router = express.Router();
Unresolved function or method Router
but this work
const express = require('express');
and if I want to do this require, what should I do.. two method in one require
const {validationResult, check} = require('express-validator/check');
node -v // v8.3.0
I'm trying to use this.. https://github.com/ctavan/express-validator#usage
Why does the following code not work
const {express} = require('express');
const router = express.Router();
You're using destructuring to extract a property that's not there. Your code is effectively doing this:
const temp = require('express');
const express = temp.express;
The object returned by require('express') has several properties, but .express is not one of them, so you end up setting express to undefined. And then when you call express.Router(), you get the error.
Your code that works is just saving the whole object, and then accessing it with the correct property names. You can keep that code, or if you know that you only are interested in the router you can do:
const {Router} = require('express');
const router = Router();
which would be pretty much the same as:
const express = require('express');
const Router = express.Router;
const router = Router();
and if I want to do this require, what should I do.. two method in one require
const {validationResult, check} = require('express-validator/check');
I'm not familiar with what that library exports. If you know that the object has both a validationResult and a check and that those are the only things you care about, then your code looks fine.
Related
When I tried to implement an express get service call with a mongoose find method it is giving me 'Product.find' is not a function error.
FYI-'Product' is the mongoose model which I imported .
ROUTES FILE
const express = require('express');
const routes = express.Router();
const Product = require('../models/product');
routes.get('/',(req,res)=>{
const list= Product.find();
res.send(list);
})
MODEL FILE
const mongoose = require('mongoose');
const productSchema = mongoose.Schema({
name:String,
subject:String
})
exports.Product = mongoose.model('Product',productSchema);
ERROR
TypeError:Product.find is not a function.
When you are exporting the model like exports.Product,you need to import the model in routes file as an object.
const {Product} = require('../models/product');
OR
we can use module.exports instead of exports.Product without making any changes in the import of routes file.
Because you are not importing your model in route file. Better if you can use module.exports instead of exports.Product.
I am learning Koa, with basic exercise, but i can´t achieve implement a simple routing, with the code that i got from this page, and this is what i did:
var koa = require('koa');
var router = require('koa-router'); //require it
var app = new koa();
var ro = router();
//and we'll set up 2 routes, for our index and about me pages
ro.get('/hello', getMessage);
function *getMessage() {
this.body = "Hello world!";
};
app.use(ro.routes());
app.listen(8008);
console.log('Koa listening on port 8008');
i did´t get any specific error, because the app run with the command node index.js, but i can see any print in the page that i routed.
and i only have 1 file in my folder myproyectoks, and it is index.js, and that's the file that i'm working.
any information that you need pls ask me :D, because i could be forgot something.
The example is out-of-date - Koa middleware is promise-based and generator functions will no longer work directly. The router documentation suggests the following form:
const Koa = require('koa')
const Router = require('#koa/router')
const router = new Router()
router.get(
'/hello',
ctx => ctx.body = 'Hello world!'
)
const app = new Koa()
app.use(router.routes())
app.listen(8008)
To note the other differences, the router module is a class that requires instantiation and the context is passed as an argument to the request handler.
I am trying to understand what is going on when I use module.exports with a variable in a model view controller type project. I just do not understand what the book means by using it in this way
var express = require("./config/express.js");
var app = express();
app.listen(3000);
module.exports = app; // my problem is right here what is it doing
console.log("Server running at http://localhost:3000/");
my config/ express file is also here
var express = require("express");
module.exports = function()
{
var app = express();
require("../app/routes/index.server.routes.js")(app);
return app;
}
The first example is exporting the Express app directly and the second example is exporting a function that returns the Express app.
This means that in the first example, require(...) will return app. In the second example, you would need to do require(...)() to have app returned.
I understand how to export routes to an index.js file but the problem I am having is I don't understand how to properly reference those external route dependencies without pasting them to the top of the file.
In other words if I have the entry point to the program ( called index.js)
and I have a list of dependencies:
index.js
const Sequelize = require("sequelize");
const connection = new Sequelize("jsfsa", "root", "password");
const bcrypt = require("bcryptjs");
const salt = bcrypt.genSaltSync(10);
const express = require('express');
const path = require('path');
const http = require('http');
const bodyParser = require('body-parser');
const app = express();
const session = require('client-sessions');
const expressHbs = require('express-handlebars');
const csrf = require("csurf");
// .....etc....
and then I have a route ( lets say a post route ) that is referenced in an external file:
routes/login.js
exports.submitLogin = (req, res) => {
// do a bunch of stuff that requires the dependencies referenced in index.js
}
I can't figure out how reference any dependencies without just placing the needed module "requires" in the routes file.
routes/login.js
const Sequelize = require("sequelize");
const connection = new Sequelize("jsfsa", "root", "password");
const bcrypt = require("bcryptjs");
const salt = bcrypt.genSaltSync(10);
const express = require('express');
const path = require('path');
const http = require('http');
const bodyParser = require('body-parser');
const app = express();
const session = require('client-sessions');
const expressHbs = require('express-handlebars');
const csrf = require("csurf");
// .....etc....
exports.submitLogin = (req, res) => {
// do a bunch of stuff that requires the dependencies referenced in index.js
}
I want to believe there is a way to place all the module references in a file my_dependencies.js and then simply reference the entire file from all the other pages in my application using a line of code as simple as a function call.
Curious if this is possible.
I've tried reading online how to deal with this issue and everything is very confusing to me.
The way I do it is to just pass the dependency variables I need directly to the functions that handle that specific route. In your case :
index.js (or wherever your route is being defined)
app.post('/someRoute', require('routes/login').submitLogin(dependency1, dependency2));
//If you are using express.Router() to handle routes/sub-routes,
//then this line could be different
routes/login.js
exports.submitLogin = function(dependency1, dependency2)
return function(req, res){
// do a bunch of stuff that requires the dependencies referenced in index.js
}
}
Of course, in this practice I'm banking on the fact that you're not going to use every single dependency in every function, which would defeat its point.
This also lets me pass other context or state dependent variables to my route handlers.
There is also the practice of simply putting your dependency variable in the app variable, like :
app.dependency=someobject;
While this would hypothetically let you access your dependency using req.app.dependency1, this practice is not recommended as it can interfere with the already existing children of the app object.
In an attempt to build a truly modular express app (one that can run stand alone or as a part of another app) I need to find out the cleanest way to find the mount path from inside the subapp. For a short example, lets say that there are two files: main.js and subapp.js
main.js
var express = require('express');
var app = express();
var localApp = express();
var subapp = require('./subapp');
app.use('/foo', subapp);
app.use('/bar', localApp);
console.log(localApp.mountpath); // yes, this prints '/bar' as expected
...
subapp.js
var express = require('express');
var app = express();
var truePath = app.mountpath; // I wish this would point to '/foo', but instead points to '/'
...
module.exports = app;
What is the best way (as in cleanest) to find the mountpath from inside the module? I'm doing this trying to solve this problem: Access to mountpath variable from inside a template using express in a non hardwired way.
As shown in the example, tried already with app.mountpath without success
As answered by alsotang, this is actually a problem of execution sequence, but it can be solved in what I think is a clean way. There is an event that is fired after the module is mounted, so you can do:
var truePath = = "/";
app.on('mount', function (parent) {
truePath = app.mountpath;
});
Where in real life truePath could be app.locals.truePath, so it can be accessed from inside the views.
eh..It's a problem of execution sequence.
In your subapp.js, the app.mountpath statement is before module.exports = app.
But only you export the app, then the app be mounted, then it would be set the mountpath property.
so, you should retrieve mountpath after the app be mounted by outer express.
My suggestion are two:
set the mountpath in your subapp.js. And outer express read this property.
perhaps you think 1 is not truly modular. so you can alternatively define a config file. and both main.js and subapp.js read mountpath from the config.
Try req.baseUrl:
app.js
var express = require('express');
var app = express();
var foo = require('./foo');
app.use('/foo', foo);
app.listen(3000);
foo.js
var express = require('express');
var router = express.Router();
router.get('/', function(req, res) {
console.log(req.baseUrl); // '/foo'
res.send('foo');
});
module.exports = router;