[英]React hook component renders before API call
我需要創建一個 React 應用程序,讓你列出 pokemons 和類型。 我從 PokeAPI 獲取數據。 從 App 組件中獲取它然后將其傳遞給子組件是一個好習慣,還是從子組件中獲取它們更好?
我在主應用程序中獲取它,我可以看到獲取工作,因為我 console.log 數據,但我的組件沒有獲取它,因此我得到一個 props.map is not a function in .
這是我的 App.js:
import React, { useState } from "react";
import logo from "./logo.svg";
import "./App.css";
import axios from "axios";
import { BrowserRouter as Router, Switch, Route, Link } from "react-router-dom";
import PokemonList from "./components/PokemonList";
const App = (props) => {
const [pokemons, setPokemons] = useState([]);
const [types, setTypes] = useState([]);
const [isLoading, setIsLoading] = useState(true);
const getPokemons = () => {
const axios = require("axios").default;
axios.get("https://pokeapi.co/api/v2/pokemon").then(function (response) {
console.log("Fetched pokemons");
console.log(response.data.results);
setIsLoading(false);
setPokemons(response.data.results);
});
};
const getTypes = () => {
setIsLoading(true);
const axios = require("axios").default;
axios.get("https://pokeapi.co/api/v2/type").then(function (response) {
console.log("Fetched types");
console.log(response.data.results);
setIsLoading(false);
setTypes(response.data.results);
});
};
return (
<Router>
<div>
<nav>
<ul>
<li>
<Link to="/pokemons" onClick={getPokemons}>
Pokemons
</Link>
</li>
<li>
<Link to="/types">Types</Link>
</li>
</ul>
</nav>
{/* A <Switch> looks through its children <Route>s and
renders the first one that matches the current URL. */}
<Switch>
<Route path="/pokemons">
<Pokemons pokemons={pokemons} />
</Route>
<Route path="/types">
<Types />
</Route>
</Switch>
</div>
</Router>
);
};
function Pokemons(pokemons) {
return <PokemonList props={pokemons} />;
}
function Types(typeList) {
return <h2>TYPES:</h2>;
}
export default App;
這是我的 PokemonList.js:
import React from "react";
import { Card } from "semantic-ui-react";
import PokeCard from "./PokeCard";
const Pokemonlist = (props) => {
let content = (
<Card.Group>
{props.map(function (object, i) {
return <PokeCard pokemon={object} key={i} />;
})}
</Card.Group>
);
return content;
};
export default Pokemonlist;
最后是我的 PokeCard.js
import { Card, Image } from "semantic-ui-react";
import React from "react";
const PokeCard = (pokemon) => {
let content = (
<Card>
<Card.Content>
<Image floated="right" size="mini" src={pokemon.img} />
<Card.Header>{pokemon.name}</Card.Header>
<Card.Meta>{pokemon.base_experience}</Card.Meta>
<Card.Description>ID: {pokemon.id}</Card.Description>
</Card.Content>
</Card>
);
return content;
};
export default PokeCard;
所以基本思路是:
在主頁上,您單擊 Pokemons 按鈕,該按鈕調用 fetch 然后呈現 PokemonList 組件,該組件基本上只是從我獲取的數據中呈現多個 PokeCard 組件。
1,我在這里缺少什么?
2、在我沒有任何變化的情況下,我需要使用useEffect嗎?
3、我應該什么時候獲取數據,在哪里獲取?
編輯:我想使用零類的鈎子
這是我的回答的摘要
useEffect
鈎子獲取結果App
組件的 useEffect 鈎子中,因為子組件在道具傳遞給它之前正在呈現,這就是您收到undefined
錯誤的原因
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