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[英]How to return a value from a async function in array.map in javascript?
[英]How to return a value from async function used inside .map function in React?
所以我用谷歌搜索了一下,我發現異步 function 返回 promise 可以在異步 function 之后通過 using.then() 訪問結果值。 這就是它無法正確渲染的原因。 我的問題是:如何從這個 promise inside.map 呈現實際值?
const storageRef = firebase.storage().ref("/assets")
const [productList, setProductList] = useState([])
useEffect(() => {
Axios.get("http://localhost:3001/product/get").then((response) => {
setProductList(response.data)
})
}, [])
const getImage = async (bannerImage) => {
const url = await storageRef.child(bannerImage).getDownloadURL();
return url;
}
Map function(返回Error: Objects are not valid as a React child (found: [object Promise])
):
{productList.map((val) => {
return (
<div key={val.id} className="product">
<div className="item">
<h1>Product title: {val.title}</h1>
<h2>Price: {val.price}</h2>
<h2>Quantity: {val.quantity}</h2>
<h2>IMG: {getImage(val.bannerImage)}</h2>
</div>
</div>
)
})}
因此,正如@Chris-G 建議的那樣,您可以 map over response.data
中的.then
鏈接到Axios.get
到 go ,獲取您需要的圖像 URL 渲染的對象。 例子:
const storageRef = firebase.storage().ref("/assets");
const getImage = async (bannerImage) => {
const url = await storageRef.child(bannerImage).getDownloadURL();
return url;
}
const [productList, setProductList] = useState([])
useEffect(() => {
Axios.get("http://localhost:3001/product/get").then((response) => {
Promise.all(response.data.map(async (rawProduct) => {
const renderReadyProduct = {
title: rawProduct.title,
price: rawProduct.price,
quantity: rawProduct.quantity
};
renderReadyProduct.img = await getImage(rawProduct.bannerImage);
return renderReadyProduct;
})).then((newProductList) => setProductList(newProductList));
});
}, [])
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