Develop Reference

How manage data when its already fetched by Axios

I am using a database with MySQL and getting it using Axios and a useEffect. Then I pass my database data to a component using a prop. Like this:
const Component = () => {
//DB
const urlProxy = "/api/cities";
//Hooks
const [data, setData] = useState([]);
//DB Fetch
const fetchData = async () => {
await axios
.get(urlProxy)
.then((res) => {
setData(res.data);
})
.catch((err) => {
console.log(err);
});
};
useEffect(() => {
return () => {
fetchData();
};
}, []);
return (
<>
<h1>Cities</h1>
<Cities api={data} />
</>
);
};
Inside of Cities Component I want to make an algorithm to manipulate that data, but I get one empty array (from const [data, setData] = useState([]). After a moment I get the fetched data from database.
const Cities = (api) => {
console.log(data) // First Print: [{api:Array(0)}] then [{api:Array(2)}]
return(
<>
...
</>
)
}
So if it prints at first an empty array I would get an error
I was thinking of using a useTimeout() but i don't know if there is a better solution, in order to use data after it's fetched.

All you would need to do is manipluate the data before you set it into your state
and the best way to wait until that is done is to have a loading state that waits for your data to be pulled and then have your useEffect manipulate it.
Something like this should work for you
const urlProxy = "/api/cities";
const Component = () => {
const [data, setData] = useState();
const [loading, setLoading] = useState(true);
//DB Fetch
const fetchData = async () => {
await axios
.get(urlProxy)
.then((res) => {
// Manipulate your data here before you set it into state
const manipluatedData = manipulateData(res.data)
setData(manipluatedData);
})
.catch((err) => {
console.log(err);
})
.finally(() =>
setLoading(false);
})
};
useEffect(() => {
return () => {
fetchData();
};
}, []);
if(loading){
return 'loading....'
}
return (
<>
<h1>Cities</h1>
<Cities api={data} />
</>
);
};

Why can't I render multiple cards using map?

I'm trying to render multiple cards by pulling data from the API. But the return is an array, I don't understand why the map is not working.
const CharacterCard = () => {
const [showModal, setShowModal] = useState(false)
const openModal = () => {
setShowModal(prev => !prev)
}
const characters = useRequestData([], `${BASE_URL}/characters`)
const renderCard = characters.map((character) => {
return (
<CardContainer key={character._id} imageUrl={character.imageUrl}/>
)
})
return (
<Container>
{renderCard}
<ModalScreen showModal={showModal} setShowModal={setShowModal} />
</Container>
)
}
export default CharacterCard
The hook is this
import { useEffect, useState } from "react"
import axios from "axios"
const useRequestData = (initialState, url) => {
const [data, setData] = useState(initialState)
useEffect(() => {
axios.get(url)
.then((res) => {
setData(res.data)
})
.catch((err) => {
console.log(err.data)
})
}, [url])
return (data)
}
export default useRequestData
console error image
requisition return image
API: https://disneyapi.dev/docs

Looks like the default value of the characters is undefined.
So something like (characters || []).map.. will help I think.
For deeper look at this you can debug useRequestData hook, as I can't see the source of that hook from you example

React-How to display make objects loop in react

Here is what i tried
episode.js
import Parser from "rss-parser";
import React from "react";
export default function Episode() {
const parser = new Parser();
const url1 = "https://anchor.fm/s/75abc654/podcast/rss";
const [data, setData] = React.useState({});
(async () => {
let data = await parser.parseURL(url1);
setData(data);
// console.log(data.title)
// data.items.forEach((item) => {
// console.log(item.title)
//console.log(item.pubDate.slice(5, 17))
//console.log(item.enclosure.url)
// console.log(item.itunes.image)
});
})();
return(
<h1>{item.title}</h1>
{data.items.map((item, index)=>{
return(
<h1>{item.title}</h1>
)})}
)
}
And the output is blank screen.. No error in console.. Help me to get the data from the rss feed without blank screen

You're calling async method unlimited time! You need to call it once via useEffect just when component rendered for first time:
import Parser from "rss-parser";
import React, { useEffect } from "react";
function Episode() {
const parser = new Parser();
const url1 = "https://anchor.fm/s/75abc654/podcast/rss";
const [data, setData] = React.useState({});
useEffect(() => {
(async () => {
let data = await parser.parseURL(url1);
console.log(data);
setData(data);
})();
}, []);
return (
<>
{data.items?.map((item, index) => (
<h1>{item.title}</h1>
))}
</>
);
}
export default function App() {
return <Episode />;
}

Just replace your async function with a useEffect hook like this
useEffect(() => {
async function fetchMyAPI() {
let data = await parser.parseURL(url1);
setData(data);
// console.log(data.title)
// data.items.forEach((item) => {
// console.log(item.title)
//console.log(item.pubDate.slice(5, 17))
//console.log(item.enclosure.url)
// console.log(item.itunes.image)
}
fetchMyAPI();
}, []);
This will be executed once every time when your component is loaded on screen
Also change the data.item.map to
{data.items?.map((item, index) => {
return <h1>{item.title}</h1>;
})}
Else it will throw error on first render

fetch dosent bring any data

when i use fetch to bring the list of notes and consol.log it nothing shows up. The url is not wrong i have carefully checked it. Here is the code:
import React, { useState, useEffect } from 'react'
const NotesListPage = () => {
let [notes, setNotes] = useState([])
useEffect(() => {
}, [])
let getNotes = async () => {
let response = await fetch('http://127.0.0.1:8000/api/notes/')
let data = await response.json()
console.log(data)
setNotes(data)
}
return (
<div>
</div>
)
}
export default NotesListPage
here is the api part:
#api_view(['GET'])
def getNotes(request):
notes = Note.objects.all()
serializer = NoteSerializer(notes, many=True)
return Response(serializer.data)

import React, { useState, useEffect } from 'react'
const NotesListPage = () => {
let [notes, setNotes] = useState([])
useEffect(() => {
getNotes();
}, [])
let getNotes = async () => {
let response = await fetch('http://127.0.0.1:8000/api/notes/')
let data = await response.json()
console.log(data)
setNotes(data)
}
return (
<div>
</div>
)
}
export default NotesListPage

You are not calling your function 'getNotes'
The way I would do it, it to fetch your data in the Effect hook and set it in your state hook there.
import React, { useState, useEffect } from 'react'
const NotesListPage = () => {
let [notes, setNotes] = useState([])
useEffect( async () => {
const response = await fetch('http://127.0.0.1:8000/api/notes/')
.then(response => response.json())
setNotes(response)
}, [])
console.log(notes)
return (
<div>
</div>
)
}
export default NotesListPage
*Edit
Cleaner would be to have the fetch in a seperate function doing the same thing and just calling that function in your effect hook (see other answer above*)

API giving data in second render in React

I was trying to fetch api with react.js but on first render its gives nothing and the second render its gives data. This makes it so when I try to access the data later for an image I get an error, TypeError: Cannot read property 'news.article' of undefined, because it is initially empty. how can I solve this?
here is my code ..
import React, { useEffect, useState } from 'react';
const HomeContent = () => {
const [news, updateNews] = useState([]);
console.log(news);
useEffect(() => {
const api = 'http://newsapi.org/v2/top-headlines?country=us&category=business&apiKey=940c56bd75da495592edd812cce82149'
fetch(api)
.then(response => response.json())
.then(data => updateNews(data))
.catch((error) => console.log(error))
}, [])
return (
<>
</>
);
};
export default HomeContent;

There is no issue with the code itself, the output you receive is expected. However, you can render the content after it is retrieved as such
import React, { useEffect, useState } from 'react';
const HomeContent = () => {
const [news, updateNews] = useState([]);
const [isLoading, setIsLoading] = useState(true);
console.log(news);
useEffect(() => {
const api = 'http://newsapi.org/v2/top-headlines?country=us&category=business&apiKey=940c56bd75da495592edd812cce82149'
fetch(api)
.then(response => response.json())
.then(data => {
updateNews(data.articles);
setIsLoading(false);
})
.catch((error) => {
console.log(error);
setIsLoading(false);
})
}, [])
return (
<>
{isLoading ?
<p>Loading...</p> :
// Some JSX rendering the data
}
</>
);
};
export default HomeContent;