Develop Reference

React: implementing a router

I tried implementing browser router, but to no success. i'm having trouble with useParams hook, and just the router in general. Looked through multiple posts and i just wasn't able to get it working. I'll post the most barebones code below, hoping someone knows the solution. I removed the traces of the router, since it didn't work.
App.js is currently empty:
const App=()=> {
return (
<Main/>
);
}
Main.jsx is my main element, where components change. There isn't a page change per se, everything is in the main element. values get passed through props into main and written into state, so the useEffect can change visibility of components based on what you chose, first category, then recipe.:
const Main =()=> {
const [showElement, setShowElement] = useState("category");
const [selectedCategory, setSelectedCategory] = useState();
const [selectedRecipe, setSelectedRecipe] = useState();
useEffect(()=> {
if (selectedRecipe) {
setShowElement("recipe")
} else if (selectedCategory) {
setShowElement("recipeSelection")
}
window.scrollTo(0, 0)
}, [selectedCategory][selectedRecipe]);
return (
<>
<Header />
<main className="main">
<div>
<div>
{showElement === "category" &&
<CategoryWindow
passSelectedCategory={setSelectedCategory}
/>
}
</div>
<div>
{showElement === "recipeSelection" &&
<RecipeSelection
value={selectedCategory}
passSelectedRecipe={setSelectedRecipe}
/>
}
</div>
<div>
{showElement === "recipe" &&
<RecipeWindow
value={selectedRecipe}
/>
}
</div>
</div>
</main>
</>
)
}
This is the recipe picker component. For example when i click on curry, i'd like the url to show /food/curry. None od the names are hardcoded, everything comes from a javascript object:
const RecipeSelection =(props)=> {
const recipies = Recipies.filter(x=>x.type === props.value);
return (
<div className="selection-div">
<div className="selection-inner">
{recipies.map(selection =>
<>
<img src={require(`../images/${selection.id}.png`)}
className="selection-single"
key={selection.id}
alt={"picture of " + selection.id}
onClick={()=> props.passSelectedRecipe(selection.id)}
>
</img>
<div className="container-h3"
onClick={()=> props.passSelectedRecipe(selection.id)}
>
<h3 className="selection-h3">{selection.name}</h3>
</div>
</>
)}
</div>
</div>
)
}

pass some value back to parent component in next js

In my nextjs project I'm displaying posts from different tags and each post have many tags. I have a post_by_tags component and I'm using that component in different sections on home page to display posts from different tags. I don't want to show repeating content as some posts have same tags and I have a array to keep post ids that are visible to website. Now I want a way to keep post ids from child component to send back to parent component which updates the array so I can filter out these posts from post object. I find some examples but mostly these are tied with onclick or onchange something like that.
Here is my parent component code:
import Head from 'next/head'
import Image from 'next/image'
import Layout from '../components/Layout';
import Hero from '../components/Hero';
import Developed_country from '../components/Developed_country';
import Posts_by_tags from '../components/Post_by_tags';
import Attorneys from '../components/Attorneys';
import Business_formation from '../components/Business_formation';
import Case from '../components/Case';
export async function getServerSideProps(context) {
// Fetch data from external API
const res = await fetch(`https://dashboard.toppstation.com/api/blogs`);
const data = await res.json();
// Pass data to the page via props
return {
props: { blogs:data}
}
}
export default function Home({blogs}) {
const blog_post_id = [];
const pull_data = (data) => {
console.log(data); // LOGS DATA FROM CHILD)
}
return (
<Layout>
<Hero/>
<Developed_country/>
<Posts_by_tags tag='business' bg='bg_grey' posts={blogs} func={pull_data}/>
<Business_formation/>
<Attorneys/>
<Posts_by_tags tag='png' bg='bg_white' posts={blogs} />
<Posts_by_tags tag='image' bg='bg_grey' posts={blogs} />
<Posts_by_tags tag='png' bg='bg_white' posts={blogs} />
<Case/>
</Layout>
)
}
Child component:
import Blogimg from '../public/img/blog.png';
import btn_arrow from '../public/img/btn_arrow.svg';
import styles from '../styles/Home.module.css';
export default function Posts_by_tags(props){
props.func('My name is xyz');
const bg = props.bg;
let align = ['start','center','end'];
let post_tags = [];
const postIds= [];
const blog_posts = props.posts.filter(bpost=>{
bpost.tags.forEach(tag => {
if(tag.toLowerCase() === props.tag){
return postIds.push(bpost._id);
}
})
});
const posts = props.posts.filter(p => {
if( (postIds.indexOf(p._id) !== -1) && p.visibility==true){
return p;
}
}).slice(0,3);
return(
<>
{posts.length == 0 ? null :(
<section id={styles.postsbytags} className={bg}>
<div className='wrapper'>
<div className="container section posts_by_tags section_ptb">
<div className='row'>
<div className='col-sm-12'>
<h3 className={`${styles.heading3} text-center`}><span className={`${styles.heading3span} ${bg}`}>{props.tag}</span></h3>
</div>
</div>
<div className='row pt_100'>
{posts.map( (post, index) =>(
<div id={`post-${post._id}`} className={`col-md-4 d-flex justify-content-md-${align[index]} justify-content-center`} key={post._id}>
<div className={styles.blog_post}>
<div className={`${styles.blog_image} text-center`}>
<span className={styles.blog_tag}>{props.tag}</span>
<Image className="img-fluid" src={post.image} alt={post.title} width={450} height={400} layout='responsive'/>
</div>
<div className='blog_content'>
<h4 className={styles.blog_title}>{post.title}</h4>
<p className={styles.blog_desc}>{post.description.split(' ').slice(0, 10).join(' ')}...</p>
</div>
</div>
</div>
))}
</div>
<div className='row'>
<div className='col-sm-12'>
<div className='blog_category pt_50'>
<a href="" className={ `btn ${styles.btn_tags} `}>See More {props.tag} <i className={styles.btn_icon}><Image src={btn_arrow} alt="btn-icon"/></i></a>
</div>
</div>
</div>
</div>
</div>
</section>
)}
</>
);
}```

Next.js markdown-blog page code not working

import { Blogs } from "../../components/Data"
import Image from "next/image";
import Link from "next/link";
import fs from 'fs'
import path from 'path'
import matter from 'gray-matter'
export default function index({ posts }) {
// const Short_Blog = Blogs.map(item =>
// <div className="BLOGS_Projects" key={item}>
// <div className="BLOGS_Projects_Image">
// <Image
// className='BLOGS_Projects_image'
// src={item['img-1']}
// layout='fill'
// // objectFit='contain'
// />
// </div>
// {/* if someone clicks on this link i want them to go to [project].js and send This item to [projcet].js */}
// <Link href={'/blogs/' + Blogs.indexOf(item)}>
// <a>{item['title']}</a>
// </Link>
// <p>{item['desc']}</p>
// </div>
// );
return (
<div className="BLOGS_Container">
<div className="BLOGS_Sub_Container">
<div className="BLOGS_New">
<h1 style={{ marginLeft: 25 + 'px' }}>Cyber-Security Blogs</h1>
<div className="BLOGS_Present">
{posts.map( post =>{
<h1 style={{zIndex: '10000'}}>{post}</h1>
})}
</div>
</div>
</div>
</div>
)
}
export async function getStaticProps() {
const files = fs.readdirSync(path.join('posts'))
const posts = files.map((filename) => {
const slug = filename.replace('.md', '')
const markdownWithMeta = fs.readFileSync(path.join('posts', filename), 'utf-8')
const { data: frontmatter } = matter(markdownWithMeta)
return {
slug,
frontmatter
}
})
return {
props: {
posts,
},
}
}
The posts object does exist but when I try to use it in the HTML, it doesn't show up anyone got any idea why this is happening?
the posts.map that I used is not giving any errors but it also doesn't show any h1 html in actual page, the actual page seems blank.

You need to return the element to render inside the callback of map function.
1st way
{posts.map((post) => {
return <h1 style={{ zIndex: "10000" }}>{post}</h1>;
})}
2nd way
{posts.map((post) => (
<h1 style={{ zIndex: "10000" }}>{post}</h1>
))}

React will not render plain html content as a string. You need to use the dangerouslySetInnerHTML prop, like so:
{
posts.map((post) => {
return <div dangerouslySetInnerHTML={{__html: post}}></div>
})
}
You can read more about it here:
https://reactjs.org/docs/dom-elements.html#dangerouslysetinnerhtml
Alternatively you can use something like next-mdx-remote, which you can learn about here:
https://github.com/hashicorp/next-mdx-remote

next.js getInitialProps doesn't work at mobile browser

I have an app works perfectly (with no error) on desktop but when I use **mobile device ** ,I found that all pages can not trigger getInitialProps method at client side only if i navigate through Link component
This My code :
return(
<>
<Head>
<title>
welcome to Anas Behhari | blogging posts for
{StaticFunction.Dateit(new Date())} |
{new Date().getFullYear() - 1 + "-" + new Date().getFullYear()}
</title>
</Head>
<div className="main">
<div className="container">
<div className="row">
<div className="col-lg-10 offset-lg-1 js-post-list-wrap Blogs-con">
<h2 className="h4 section-title">
<span> Latest posts </span>
</h2>
{Blogs.map((blog) => (
<Article blog={blog} key={blog._id} />
))}
{BlogList}
</div>
</div>
</div>
</div>
</>
)
blogs.getInitialProps = async (ctx) => {
try {
const res = await axios.get("http://localhost:3000/api/blogs?offset=0&max=5");
const Blogs = res.data;
return { Blogs };
} catch (error) {
return { error };
}
};
export default blogs;

Well, after 2 days of searching on the internet I figured out that I just need to change a bit inside the getInitialProps function.
The main factor was to get rid of the Axios and replace it with Fetch API
export async function getStaticProps() {
const res = await fetch(`http://localhost:8080/api/blogs}`)
const Blogs = await res.json()
if(!Tags) return {props:{error:true}}
return {
props: {
Blogs,
},
}
}
if this solution didn't work getServerSideProps instead of
getStaticProps

Routing not working using Gatsby - reach-router

I'm trying to render a blog as a card then open it up as a page , but its proving to be difficult using Gatsby. I did the exact same thing fine with react using React router but it doesn't seem to be working with Gatsby. I know I can use GraphQL but surely I can do the same thing using REST. Im using Contentful btw
I switched to reach router as suggested in another post but that doesnt work.
I kept getting this error when I used react-router-dom:
Invariant failed: You should not use <Link> outside a <Router>
Fetching Blog contents
function Blog() {
const [blogs, setBlogs] = useState([])
const [image, setImage] = useState()
const [selectedBlog, setSelectedBlog] = useState(blogs)
useEffect(() => {
fetch("http://cdn.contentful.com...")
.then(response => response.json())
.then(data =>
setBlogs(data.items)
)
}, [])
console.log(blogs)
return (
<>
<div className="card-flex" >
{selectedBlog !== null ? blogs.map((blog =>
<Card title={blog.fields.title} date={blog.fields.date} introduction={blog.fields.introduction} mainBody1={blog.fields.mainBody1} mainBody2={blog.fields.mainBody2} setSelectedBlog={selectedBlog}
/>
)):
<Article title={blogs.find(d => d.fields.title === selectedBlog)} />
}
</div>
</>
)
}
export default Blog
Blog Card
function Card(props) {
console.log(props)
return (
<div class="container">
<div class="card">
<div class="card-header">
<img style={{backgroundImage: "url('https://i.pinimg.com/564x/7f/bb/97/7fbb9793b574c32f5d28cae0ea5c557f.jpg')"}}/>
</div>
<div class="card-body">
<span class="tag tag-teal">{props.tags}</span>
<h4>{props.title}</h4>
<p style={{fontSize:"17px", paddingTop:"10px"}} >{props.introduction}</p>
<div class="card-user">
<Link
to={{
pathname: '/article',
state: {
title: props.title,
introduction: props.introduction
}
}}
>
<button>read more</button>
</Link>
<div class="user-info">
<h5 >{ props.date}</h5>
</div>
</div>
</div>
</div>
</div>
)
}
export default Card
**Article **
import React from 'react'
import './Article.css'
import { useLocation } from "#reach/router"
function Article(props) {
// useLocation to access the route state from Blog.js
const { state = {} } = useLocation();
console.log(state)
return (
<div className="main">
<h1 className="title">{state.title}</h1>
<p className="intro">{state.introduction}</p>
<p className="main1">{state.mainBody1}</p>
<p className="main2">{state.mainBody2}</p>
</div>
)
}
export default Article

I think you are mixing stuff. Gatsby extends from #reach/router so you don't need to use its notation. Your Link should look like:
<Link
to={`/article`}
state={{
title: props.title,
introduction: props.introduction
}}
>
Assuming your /article page exists under /pages folder.