我使用以下组件在 Google Cloud FireStore 集合中添加新数据:
import React, { useState } from 'react';
import { db } from '../firebase';
const AddCard = ({ totalDoclNumbers }) => {
const [newOriginalText, setNewOriginalText] = useState([]);
const [newTranslatedText, setNewTranslatedText] = useState([]);
const nextNumber = totalDoclNumbers + 1;
const onAdd = async () => {
await db.collection('FlashCards').add({
originalText: newOriginalText,
translatedText: newTranslatedText,
customId: Number(nextNumber),
});
};
return (
<ul>
<li key={nextNumber}>
<input
type='text'
readOnly
defaultValue={nextNumber}
/>
<div>
<textarea
placeholder='English'
onChange={(e) => setNewOriginalText(e.target.value)}
/>
</div>
<textarea
placeholder='Translation'
onChange={(e) => setNewTranslatedText(e.target.value)}
/>
<button onClick={onAdd}>
Add
</button>
</li>
</ul>
);
};
导出默认的AddCard;
添加按钮有效,我可以看到新数据已添加到 Google 服务器上的集合中,但是为了能够看到这些新数据,我必须刷新页面。
为了修复它,我决定使用onSnapshot函数如下:
import React, { useState } from 'react';
import { db } from '../firebase';
const AddCard = ({ totalDoclNumbers }) => {
const [newOriginalText, setNewOriginalText] = useState([]);
const [newTranslatedText, setNewTranslatedText] = useState([]);
const nextNumber = totalDoclNumbers + 1;
const onAdd = async () => {
await db.collection('FlashCards').add({
originalText: newOriginalText,
translatedText: newTranslatedText,
customId: Number(nextNumber),
});
};
const renderDocList = () => {
return (
<ul>
<li key={nextNumber}>
<input
type='text'
defaultValue={nextNumber}
/>
<div>
<textarea
placeholder='English'
onChange={(e) => setNewOriginalText(e.target.value)}
/>
</div>
<textarea
placeholder='Translation'
onChange={(e) => setNewTranslatedText(e.target.value)}
/>
<button onClick={onAdd}>
Add
</button>
</li>
</ul>
);
};
db.collection('FlashCards').onSnapshot((snapshot) => {
let changes = snapshot.docChanges();
changes.forEach((change) => {
if (change.type === 'added') {
renderDocList();
}
});
});
return <>{renderDocList()}</>;
};
export default AddCard;
但是虽然新数据被添加到 FireStore 集合中,但我在页面上看不到任何变化。我仍然必须刷新(重新加载)浏览器才能看到这些更改。我究竟做错了什么?