According to the Next.js docs for the app directory:
"Whenever possible, we recommend fetching data inside Server Components. Server Components always fetch data on the server."
This is great because I am hitting an external API (where I cannot change the CORS policy - Allow-Origins...).
I have a page (server component) with a form (client component), and I am trying to hit the API using the server component.
Home page
import Form from './Form';
export default function Home() {
handleSubmit = () => {...submit logic}
return <Form onSubmit={handleSubmit} />
}
Form Component
'use client'
export default function Form({ onSubmit }) {
return <form onSubmit={handleSubmit}>...</form>
}
When I try to pass the handleSubmit function to the client component, I get this error:
Functions cannot be passed directly to Client Components because they're not serializable.
I'm not sure what that means.
Is there a way to pass functions to client components?
I need to fetch from a server component because the API has CORS policy. Is it possible to do what I am trying to accomplish?
Do you have any error.js in your directory?
Add use client at the top of the file.
See reference here:
https://github.com/vercel/next.js/issues/42408
https://beta.nextjs.org/docs/rendering/server-and-client-components
Hope this helps.
I need to fetch from a server component because the API has a CORS policy. Is it possible to do what I'm trying to accomplish?
The CORS policy applies to any incoming request (whether the request comes from a front or server component doesn't matter).
What is the HTTP method you are going to use in your function? If it's POST, PUT or DELETE, you don't absolutely need to do it in a server component (the purpose of a server component is to optimize SEO by sending the data already loaded - it is called server-side rendering).
If this is a GET, what are you trying to accomplish? Dynamically load data based on what the user has chosen to fill in?
If so, I think it's easier to do this on the client side. Otherwise you don't need a form.
I'm looking forward to create a web app with NextJS and Google's Firebase. The app has an admin panel and a public site. In the admin panel should have options to edit the public site's navigation.
So I was thinking is it wise to have client-side fetching navigation data on each refresh or is there a better way to get dynamic and up-to date navigation data with as little API request as possible?
This really depends on your use case. In Next.js there are 3 diffrent types for data fetching.
Static site generation - SSG
This fetches the data and renders the pages on build time. This is greate for Pages that don't change to often. Like a blog for example.
Server site rendering - SSR
This fetches the data and renders the pages on each request from a user. This is usefull for data that changes quickly and has to be up to date.
Increment static regeneration - ISR
This allows for a compromise between the 2 types i described above and might be what your looking for if you want to use as little API requests as possiblie. With it you can staticly regenerate the page at a certain time interval.
export async function getStaticProps(){
//fetch data from firebase ...
return {
props: { data },
revalidate: 60,
}
}
Can anyone please explain me the concept of client side and server side in Next.js as they have mentioned in their documentation. What I know is that Next.js works on react which is client side and run in the browser and server side means the api (backend). Any help would be appreciated. Thanks
From Next.js documentation:
This function gets called at build time on server-side. It won't be called on client-side, so you can even do direct database queries. See the "Technical details" section.
export async function getStaticProps() {
const postsDirectory = path.join(process.cwd(), 'posts')
const filenames = await fs.readdir(postsDirectory)
}
I started writing NextJS app few months before, i'll explain as far as i know check whether it would be helpful.
Your understanding on client and server(API) is correct but in case of NextJS there is another client side and server side as NextJS is used for Server-Side Rendering(SSR).
In simple a same page Ex: pages/home.js when loaded with browser hard re-load https://example.com/home is loaded as server side. Pages written under /pages/ folder will be rendered server side on navigation. So the DOM elements of the page will be available in page source(view page source option in browser) which will be used by crawlers too.
You can find the difference by checking whether type of window !== 'undefined', as window represents browser which is client and view page source of browser represents server side rendering.
In Pages also you can check
Create a Next.js project
Have two pages index.js and home.js
In home.js write Home.getInitalProps method which is similar to useEffect or componentDidMount in react component. Here pages cannot contain componentDidMount or useEffect instead all API calls before render has to be done in getInitialProps or other related methods.
Home.getInitialProps = async (context) => {
const { req, query, res, asPath, pathname } = context
if (!req) {
if (typeof window !== 'undefined') {
//its server side request happened on
}
} else {
// its client side call that calls getInitialProps when routing
happened Router.push('/home') from index page or inside components
rendered from pages/index.js
}
}
Let me know if you need some more details, we can explore and figure it out.
I have a Next.js (fix may not necessarily have anything to do with Next.js) app that I want to limit some navigation. This page in the Next.js docs mentions "you should guard against navigation to routes you do not want programmatically", but I'm unsure how to do this. Let's say I have the following pages:
/bikes
/boats
/cars
and I only want to allow a user to see /bikes. How would I be able to do this. I'm able to redirect from an undesired page to an acceptable page, but only after the undesired page loads. Is there a way to redirect before this (maybe by changing the URL as soon as it is changed)?
I appreciate that this is an old question, however, I wish I had known this answer to it earlier than I did, so I would like to answer it for the record.
Our next.js app had a relatively complex set of permissions associated with accessing each page (with the ability to access the page, or different data presented on it) based on the authentication status of a user as well as the authorization scopes granted to them.
The solution that we used was the to return a redirect from getServerSideProps(). Normally one would return something like the following:
const getServerSideProps = (context) => {
return {
props: {
myProp: 1
}
};
}
However, it is also possible to return a redirect. This redirect is performed on the server side prior to the page content being sent to the browser:
const getServerSideProps = (context) => {
return {
redirect: '/login'
};
}
This is relatively new functionality - it was only pulled in towards the end of last year, and there isn't much documentation for it anywhere, but it perfectly serves this use case.
I'm new to the react world and to the fullstack world as a whole but I've searched endlessly for an answer to the following and some guidance would be really appreciated.
I'm creating an app using React and Express. It requires authentication so I was planning on using Passport to help. The client side JS uses React Routers to navigate through the website. That's all fine but my issue is with the initial GET request made by the browser.
I'll first describe my specific app requirements and then generalize what I don't understand.
As I said, my application requires OAuth2 authentication. If you try to GET a path on my website and you're not logged in, it should just load the login page. If you are logged in, then load as normal and find your path. Similar to facebook, I'd like the login URL to be the same as the "feed" page. So similar to how facebook.com '/' route is either the login page or your new feed depending on whether you are signed in, I want the same thing.
From what I understand, Passport authenticates on the back end by checking the request header. So I understand that I should have some kind of middleware that says "if user is signed in, continue down the routes otherwise render sign in page" ... How is this done? What would the code look like? My only experience with Express was from an intro class which used res.render to send back an HTML file and pass it through some template engine like handlebars. But I have no idea how it'd work with react routes. Would i still use res.render()? Something else?
Let's say my index.html has the root div to inject the react into. If I had to guess, I'd send back that index.html page with the .js file with the routes and somehow on the backend send back the route I want it to match on my react routes (either the login one or the user requested)??
More generally, I guess I'm just confused how the initial request to a website using react routes is done. 1) How does the server interact with everything to render what I asked for? 2) What would the code look like for that. My only experience with React is from a basic Udemy course that just used "react-scripts start" to render the page.
After spending the entire day Googling this question it led me to SSR which is a rabbit-hole of its own and I'm not even sure if its what I need to help me. Is it?
I'm clearly missing some fundamental knowledge as this is really tripping me up so if you have any resources to learn more just post them. Thanks!
I understand your struggle as I've had to go through it myself when combining front-end with back-end, specifically React and Node. So first things first, we know that the browser/client will always initiate a request to the server, so how does React Router take control of the routes? Well its plain simple actually, all you have to do is return the entire react app from any route from your express server. The code will look something like this:
const express = require('express');
const app = express();
app.get('/*', (req, res, next) => {
// Return React App index.html
});
app.listen(3000);
Once the react app renders on the user browser (don't worry about paths, as react will automatically render according to the URL based on the code you wrote in the client side, it will also take care of authentication vs feed page when it will scan for your local storage, cookies, etc), it will take control of routing, instead of a request going to the express server. But what happens when we request data from our server, well it returns react app on each route so we need to setup an api route to handle any data requests.
app.get('/api/v1/*', (req, res, next) {
// Return some data in json format
});
Hopefully, this gives you insight about what you were looking for.
I think the fundamental gap you're struggling with stems from that lot of those 'intro courses' shove the entire browser client into the application server to get things up and running quickly, as in, the Node server renders the entire React app AND operates as an API...
// Ajax request from React app to: http://example.com/api
app.use('/api/*'),()=> {
res.send({ <!-- some JSON object -->})
})
// User visits in browser: http://example.com/**/*
app.use('/*',()=>{
res.render(<!-- entire React App sent to browser -->)
})
The first request (assuming the user doesn't visit /api/* ) will just send down the React bundle. Further user navigation within the client would generally send XHR requests (or open WebSockets) from the React app to Express routes running on the same node program.
In many situations it makes sense to have these parts of your program separated, as by having react delivered from a completely different location than where it requests data. There's many reasons for this, but optimizing computing resources to their differing demands of CPU, memory, network .etc and manageability of code/deployment are the big reasons for me.
For example...
User visits: http://example.com *
Nginx, Apache, a 'cloud proxy' .etc direct the traffic to a static React bundle, which has no authentication and never makes contact with your Node server.
If the user has Authenticate previously they will have token in local storage (if you're using JWTs for Authentication) and your React app will be configured to always check for these tokens when you first it is initially loaded.
If the user has a token it will send an Ajax request in the background with the token as a Header Bearer and will send back user data, then redirect them to an 'Authenticated page' like the FB feed you mention.
If they don't have a token or the token Authentication fails then React will redirect them to the Login or Registration page
React
React basically high jacks the browser's native 'location' functionality (whats displayed after you domain name). So any events after the initial page load (buttons clicks and such) are handled entirely by React internally and uses those routes to determine what to display or what data to fetch from the API through Ajax (XHR).
If the user performs a hard page reload then that request will go back to the server and it will perform the whole cycle over again
React Router
Allows you to do 2 things simultaneously...
Manipulate the browser Location and History objects.
Use that History and Location information elsewhere by detecting changes and sending off events.
SSR
I've only toyed around with SSR so I can speak to it, but its provides extremely low latency for initial renders, doing it in 1 network request, so you want to use it areas of your program where thats important.
Not sure if this answers you question, but let me know if you would like me to elaborate on anything or provide some more detailed resources.
SSR is a little bit confuses for developer that has less experience, let forget it for now.
It will be more easier for you to assume that frontend JavaScript (React) and backend Javascript (NodeJS) are two separate apps, and they communicate to each other via API.
here the code that show Login component and Feed component depending on whether you are signed in
import React, { Component } from "react";
import axios from "axios";
class Home extends Component {
constructor() {
const accessToken = localStorage.getItem("accessToken");
this.state = {
accessToken,
feeds: []
};
}
componentDidMount() {
if (this.state.accessToken) {
axios(`api/feeds?accessToken=${this.state.accessToken}`).then(({ data }) => {
this.setState({
feeds: data
});
});
}
}
render() {
if (this.state.accessToken) {
return <FeedsComponent feeds={this.state.feeds} />;
}
return <LoginComponent />;
}
}
and this is your backend
const express = require("express");
const app = express();
app.get('/api/feeds', (req, res, ) => {
const feeds = [
{},
{}
]
res.status(200).json(feeds);
});
app.listen(3001);
just keep in mind that they are two separate apps, the can be in two different folder, different server, different port.
Simply point Express to the folder containing your React files or build files.
app.use(express.static(__dirname + '/dist'));
where 'dist' contains the build files
See docs for more details