Calling an endpoint inside the node project itself? - javascript

I am creating a MERN app that adds meta tags to React pages without SSR. So, I need to read the query inside the main file of the server and pass the appropriate metadata content to each page.
I am using this in the server.js file:
const indexPath = path.resolve(__dirname, 'build', 'index.html');
// static resources should just be served as they are
app.use(express.static(
path.resolve(__dirname, 'build'),
{ maxAge: '30d' },
));
// here we serve the index.html page
app.get('/*', (req, res, next) => {
fs.readFile(indexPath, 'utf8', (err, htmlData) => {
if (err) {
console.error('Error during file reading', err);
return res.status(404).end()
}
// get post info
const postId = req.query.id;
const post = getPostById(postId);
if(!post) return res.status(404).send("Post not found");
// inject meta tags
htmlData = htmlData.replace(
"<title>React App</title>",
`<title>${post.title}</title>`
)
.replace('__META_OG_TITLE__', post.title)
.replace('__META_OG_DESCRIPTION__', post.description)
.replace('__META_DESCRIPTION__', post.description)
.replace('__META_OG_IMAGE__', post.thumbnail)
return res.send(htmlData);
});
});
Here the getPostById is statically defined in a file. But I want to fetch it from my db.
My file structure is:
server.js
controllers
- posts.js
routes
- posts.js
I've separated the logic from route. So my routes/posts.js file looks like:
import { getPost, createPost } from '../controllers/posts.js';
const router = express.Router();
router.get('/', getPost);
router.post('/', createPost);
export default router;
So, in order to dynamically pass the meta content, I need to read the API endpoint for each request and pass the appropriate data. For this, I need to call the endpoints directly inside my node project. How to do that?
I'd appreciate any help. Thank you.

If you really want to call your own http endpoints, you would use http.get() or some higher level http library (that is a little easier to use) such as got(). And, then you can make an http request to your own server and get the results back.
But ... usually, you do not make http requests to your own server. Instead, you encapsulate the functionality that gets you the data you want in a function and you use that function both in the route and in your own code that wants the same data as the route. This is a ton more efficient than packaging up an http request, sending that request to the TCP stack, having that request come back to your server, parsing that request, getting the data, forming it as an http response, sending that response back to the requester, parsing that response, then using the data.
Instead, if you have a common, shared function, you just call the function, get the result from it (probably via a promise) and you're done. You don't need all that intermediate packaging into the http request/response, parsing, loopback network, etc...

Related

Call a router WITHIN Nodejs after a route has been called

I am using Expressjs and the Auth0 API for authentication and ReactJs for client side.
Because of the limitations of the Auth0 API (spoke with their team) I am sending updated user details to my backend and then using app.set() to be able to use the req.body in another route.
I need to call the app.patch() route automatically after the app.post() route has been hit.
The end goal is that the users data will be updated and shown client side.
const express = require('express');
const cors = require('cors');
const path = require('path');
const app = express();
require('dotenv').config()
const { auth } = require("express-openid-connect");
app.use(express.json());
app.use(cors());
app.use(express.static(path.join(__dirname, 'build')));
app.use(
auth({
issuerBaseURL: process.env.AUTH0_ISSUER_BASE_URL,
baseURL: process.env.BASE_URL,
clientID: process.env.AUTH0_CLIENT_ID,
secret: process.env.SESSION_SECRET,
authRequired: false,
auth0Logout: true,
})
);
app.get('/', async (req, res) => {
res.sendFile(path.join(__dirname, 'build', 'index.html'));
});
app.get('/api', async (req, res) => {
const stripe = require('stripe')(`${process.env.REACT_APP_Stripe_Live}`);
const invoice = await stripe.invoices.list({
limit: 3,
});
res.json(invoice);
});
app.post('/updateuser', (req, ) => {
app.set('data', req.body);
})
app.patch(`https://${process.env.AUTH0_ISSUER_BASE_URL}/api/v2/users/:id`,(req,res) => {
let val = app.get('data');
req.params = {id: val.id};
console.log(req.params);
})
app.listen(process.env.PORT || 8080, () => {
console.log(`Server listening on 8080`);
});
I'd suggest you just take the code from inside of app.patch() and make it into a reusable function. Then it can be called from either the app.patch() route directly or from your other route that wants to do the same funtionality. Just decide what interface for that function will work for both, make it a separate function and then you can call it from both places.
For some reason (which I don't really understand, but seems to happen to lots of people), people forget that the code inside of routes can also be put into functions and shared just like any other Javascript code. I guess people seems to think of a route as a fixed unit by itself and forget that it can still be broken down into components and those components shared with other code.
Warning. On another point. This comment of yours sounds very wrong:
and then using app.set() to be able to use the req.body in another route
req.body belongs to one particular user. app.set() is global to your server (all user's requests access it). So, you're trying to store temporary state for one single user in essentially a global. That means that multiple user's request that happen to be in the process of doing something similar will trounce/overwrite each other's data. Or worse, one user's data will accidentally become some other user's data. You cannot program a multi-user server this way at all.
The usual way around this is to either 1) redesign the process so you don't have to save state on the server (stateless operations are generally better, if possible) or 2) Use a user-specific session (like with express-session) and save the temporary state in the user's session. Then, it is saved separately for each user and one user's state won't overwrite anothers.
If this usage of app.set() was to solve the original problem of executing a .patch() route, then the problem is solved by just calling a shared function and passing the req.body data directly to that shared function. Then, you don't have to stuff it away somewhere so a later route can use it. You just execute the functionality you want and pass it the desired data.

How do I properly set routes up for a Single Page App using Express.js?

I am attempting to build a single page app using Express.js. On my index.html page, I have a basic form, which upon submit will make a request to an API, retrieve the data, parse it, and then I want to render the parsed data as a list of links. Right now I am able to render the index page, and I can make the submission call to the API from the form that I added to the page. What I am confused about is how to properly redirect the data I get from the API call and then render it on the same page. I've built simple apps using Express before where there were multiple views, but never a single page app. For those apps, I know that for the response you could call something like res.render('name of view to render', data), but that is not working in this case. I've tried to find some solutions through this site and via the Express docs, but I have not seen anything that didn't also include using another framework like Angular. For the purposes of this app, I need to not include any additional frameworks, and I am a bit lost.
My function for calling the API looks like this right now. When it is called, I am directed to a page that just has the json displayed
app.use(express.static(path.join(__dirname, '/public')));
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
app.use('/', express.static(path.join(__dirname, 'public')));
app.get('/search', function(req, res) {
var title = req.query.movieTitle;
var url = 'http://www.omdbapi.com/?s=' + title;
request(url, function (err, response, body) {
var results = JSON.parse(body);
var movieTitles = results.Search;
console.log(movieTitles);
res.send(movieTitles);
});
});
The basic thing you have to do is:
define routes which your back-end app has to respond with the spa
send your "skeleton" file to the response on that routes
Example code:
const handler = (req, res) => res.send(path.join(__dirname, "path/to/your/index.html"))
const routes = ["/", "/hello", "/world"]
routes.forEach( route => app.get(route, handler) )
This should get you started

Including a response header with res.redirect

A Node.js app needs to:
1.) receive data from another serve that calls /some_endpoint,
2.) process the data it receives to create a String result jwtString,
3.) redirect the user to the root / url of the AngularJS app while passing the jwtString as a res.header included inside the res.redirect.
What specific changes need to be made to the Node.js routing code below in order for the _jwt header to be successfully passed from the Node.js app to the client AngularJS at at /?
app.get('/some_endpoint', function(req, res) {
//Process data from another server that was redirected here.
//then send the result of that processing in jwtString while
//redirecting user to the root url of the Angular app that
//is served by this Node.js instance.
res.setHeader('_jwt', jwtString);
res.redirect('/');
});
app.get('*', function(req, res) {
var queryData = url.parse(req.url, true);
console.log('in get *, queryData is: ');console.log(queryData);
res.sendfile('./public/index.html'); // load the single view file (angular will handle the front-end)
});
When I run the code above, I cannot seem to find the _jwt header in the Network tab of the FireFox developer tools.

Express response payload on response finish

I have an Express.JS server with many res.json. To perform statistics, logging and debugging, I want to capture the response payload in a catch-all hook.
I have found the finish event res.on('finish') but I cannot find how to extract the response payload from it.
res.on('finish') is called once the data has been sent, so the payload doesn't necessarily exist on the server any more. You can add middleware to express to intercept every request and then override the .json method to log the data as the function is called:
router.use('/', (req, res, next) => {
var old = res.json.bind(res);
res.json = (body) => {
//Do whatever
old(body);
}
next();
})

Nodejs, expressjs - how to serve delayed response

I am building a webservice, for which i am using nodejs, phantomjs and expressjs. I am learning all the three.
I want to serve a delayed response to the clients after processing their query. Like for example,
I am processing certain inputs from my client, then, i want to process the data at the backend which will take approx 10 sec on an avg. Then i wanted to serve this page to the client.
Is it possible in node to send multiple responses to the same request or delayed responses so that the template will automatically update the contents.
Or , should i use the same method , like store the json in a file in the server , then serve the page with ajax which will query the page.
please help me. here is the code which i wrote ,
app-server.js(the main file):
// import express module
var express = require('express');
var bodyParser = require('body-parser');
var app = express();
// define all required template files to be served and also define the template engine
app.engine('.html', require('ejs').__express);
app.set('views', __dirname + '/views');
app.set('view engine', 'html');
// Useful modules
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({extended: true}));
// import the routes
require('./router')(app);
app.listen(8080);
router.js:
var crypto = require('crypto');
var express = require('express');
module.exports = function (app) {
// define the static routes.
app.use('/static', express.static('./static'));
app.use('/media', express.static('./media'));
//defining the controller.
var parserlib = require('./controller.js')
// Define the home root path
app.get('/', function (req, res) {
// shows the home search page.
res.render('index', {content:'template success'});
});
app.get('/search', function(req, res){
res.redirect('/');
});
app.post('/search', parserlib.parserlib);
}
controller.js:
var crypto = require('crypto');
var path = require('path')
var childProcess = require('child_process')
exports.parserlib= function(req, res){
var output = '';
var url = req.body.search_url;
var childArgs = [
path.join(__dirname, 'external-script.js'),
url,
]
// execute the script in a separate thread.
childProcess.execFile(binPath, childArgs, function(err, stdout, stderr) {
// handle results
console.log(stdout);
output = stdout;
//console.log(err);
//res.send(output);
});
//res.send(output);
};
so , what i want to see is, first send a response to client stating that its loading, then i want to update the with processed data. In other languages its not possible to send multiple responses. Not sure about nodejs.
Also, do i have to store the json output from the processed lib to a file and then use ajax to query ? or is it possible to directly update the json object to the client ?
Thanks
This is just not how HTTP works. The clients won't expect it. This has nothing to do with Node or any other framework. The way to do what you're attempting is to actually send a response that the thing is loading, and then have some other mechanism for reporting state.
As an example, you might design a RESTful API. In that RESTful API you might define a endpoint for creating new things:
POST /api/things
The client would post data to that to create a new thing. The response should be something that provides a location of the newly created resource, for example an HTTP 301 to /api/things/1.
If the user goes to /api/things/1 and the thing isn't done getting made yet, then you can either do a temporary redirect (303) to /api/things/1/status which provides some helpful status information, or just issue a 404.
If you actually want to send back server-side pushes of status information, then you should be looking at WebSockets or a pure Socket API of some kind, neither of which is provided by Express, but both of which are available in Node (checkout the socket.io library and the net core library)

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