英文:
Does flatlist automatically support pagination?
问题
在我的React Native应用程序中，我使用'FlatList'来呈现从后端查询的产品，如下所示。我想知道这是否自动具有分页功能，还是我需要手动实现分页，如果需要手动实现，最佳方法是什么？
import { DataStore } from '@aws-amplify/datastore';import { Product } from "../src/models";const [allProducts, setAllProducts] = useState<Product[]>([]);useEffect(() => {const getAllProducts = async () => {await DataStore.query(Product, a => a.Available("eq", true)).then(setAllProducts);};getAllProducts();}, []);<FlatListdata={allProducts}renderItem={({ item }) => <ProductComponent info={item} />}numColumns={2}/>
这段代码中，您使用了FlatList来呈现产品数据，但它并没有自动处理分页。您需要手动实现分页功能。实现分页的最佳方法通常涉及以下步骤：
- 跟踪当前页面和每页的项目数量。
- 当用户滚动到列表底部时，加载更多项目。
- 更新数据源以包括新加载的项目。
您可以使用FlatList的onEndReached属性来检测用户是否滚动到列表底部，然后触发加载更多项目的逻辑。
英文:
In my react native application I use a 'Flatlist' to render my products which are queried from backend as shown below. I want to know does this automatically has pagination or do I have to implement pagination manually, if so what is the best way to do it?
import { DataStore } from '@aws-amplify/datastore';import {Product} from "../src/models";const [allProducts, setAllProducts] = useState <Product[]>([]);useEffect(() => {const getallProducts = async () => {await DataStore.query(Product, a => a.Available("eq", true)).then(setAllProducts);};getallProducts();}, []);<FlatListdata={allProducts}renderItem = {({item}) => <ProductComponent info={item} />}numColumns={2}/>
答案1
得分: 2
Idea: 滚动到FlatList的底部，调用获取数据的函数并将响应映射到当前数据。
您可以使用FlatList的属性来实现这一点：
- onEndReachedThreshold：列表底部在可见列表长度单位内离结束多远。
- onEndReached：当滚动位置接近onEndReachedThreshold时的回调。
AWS Amplify DataStore文档：
https://docs.amplify.aws/lib/datastore/data-access/q/platform/js/#pagination
示例：
const [page, setPage] = React.useState<number>(0)const onLoadMore = async () => {await DataStore.query(Product, (a) => a.Available("eq", true), { page: page, limit: 100 }).then((response) => setAllProducts([...allProducts, ...response.dataProducts]))setPage(page + 1)}return (<FlatListdata={allProducts}renderItem={({ item }) => <ProductComponent info={item} />}numColumns={2}onEndReachedThreshold={0.2} // 当内容末尾在列表可见长度的20%内时触发onEndReached。onEndReached={onLoadMore}/>)
请注意，我已经根据您提供的代码部分进行了翻译，如果您需要更多帮助或有其他问题，请随时提出。
英文:
Idea: Scroll to FlatList's bottom, call function get data and map response to current data.
You can do that with FlatList's props:
- onEndReachedThreshold: How far from the end (in units of visible length of the list) the bottom edge of the list.
- onEndReached: callback when scroll position gets within onEndReachedThreshold.
AWS-amplify DataStore doc:
https://docs.amplify.aws/lib/datastore/data-access/q/platform/js/#pagination
Example:
const [page, setPage] = React.useState<number>(0)const onLoadMore = async () => {await DataStore.query(Product, (a) => a.Available("eq", true)).then(() => setAllProducts([...allProducts, ...response.dataProducts]),{ page: page, limit: 100 },)setPage(page + 1)}return (<FlatListdata={allProducts}renderItem = {({item}) => <ProductComponent info={item} />}numColumns={2}onEndReachedThreshold={0.2} // trigger onEndReached when the end of the content is within 20% the visible length of the list.onEndReached={onLoadMore}/>)
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