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ViewsHow to avoid unnecessary API calls with useEffect?
I'm still beginner to ReactJS and I'm having trouble rendering a list.
I don't know why, all the time calls are being made to my API. Since I don't put any dependency on useEffect, that is, I should only render my function once.
I don't understand why this is happening. Can you tell me what I'm doing wrong?
Here's my code I put into codesandbox.io
import React from "react";
import axios from "axios";
import "./styles.css";
const App = () => {
const BASE_URL = "https://pokeapi.co/api/v2";
const [pokemons, setPokemons] = React.useState([]);
const getAllPokemons = async () => {
const { data } = await axios.get(`${BASE_URL}/pokemon`);
data.results.map((pokemon) => getPokeType(pokemon));
};
const getPokeType = async (pokemon) => {
const { data } = await axios.get(pokemon.url);
setPokemons((prev) => [...prev, data]);
};
React.useEffect(() => {
getAllPokemons();
}, []);
console.log(pokemons);
return (
<div className="App">
<h1>Hello CodeSandbox</h1>
{pokemons.map((pokemon) => (
<p key={pokemon.id} style={{ color: "blue" }}>
{pokemon.name}
</p>
))}
</div>
);
};
export default App;
Thank you very much in advance.
2 answers
Answer question0
Your issue is that you are calling setPokemons inside getPokeType (which is called for each data in part). Your useEffect is called just once (as expected) and the ${BASE_URL}/pokemon call is executed just once too. But getPokeType is called 20 times and the pokemons state is changed 20 times as well (once for each instance from data.results).
What I would reccomend instead in your case is creating a list of all the pokemons and setting the state just once at the end. So something like:
...
const getPokeType = async (pokemon) => {
const { data } = await axios.get(pokemon.url);
return data;
};
const getAllPokemons = async () => {
const { data } = await axios.get(`${BASE_URL}/pokemon`);
const pokemons = await Promise.all(
data.results.map((pokemon) => getPokeType(pokemon))
);
setPokemons(pokemons);
};
React.useEffect(() => {
getAllPokemons();
}, []);
...
0
I was just having the same issue in my project the way I solved is by moving the function definition inside the useEffect
React.useEffect(() => {
const getAllPokemons = async () => {
const { data } = await axios.get(`${BASE_URL}/pokemon`);
data.results.map((pokemon) => getPokeType(pokemon));
};
getAllPokemons();
}, []);
If this solves your problem please accept the answer.