reactjs - 使用 useReducer 手动获取数据
问题描述
我不仅需要在 ComponentDidMount 上使用,loadData()
还需要在 methodsonFiltersClear
和. 我怎么能那样做?我需要一些自定义数据获取钩子还是有其他方法可以做到这一点?onApplyFilters
onPageChange
import { Table } from "lpcnse-core-front";
import Filters from "./Filters/Filters";
import { styles } from "./checks.css";
const STATUSES_PARENT_ID = "2F24B71C-C70A-4980-9D45-E4134D38E9E0";
const ITEMS_PER_PAGE = 20;
const INITIAL_PAGINATION = {
pageNumber: 1,
itemsPerPageCount: ITEMS_PER_PAGE,
totalCount: 0,
pageCount: 0
};
const INITIAL_FILTERS = {
title: "",
сontrolledObject: "",
status: null
};
const initialState = {
filters: INITIAL_FILTERS,
checks: [],
pagination: INITIAL_PAGINATION,
selectedCheckId: null,
statusList: []
};
const reducer = (state, action) => {
switch (action.type) {
case "FETCH_DATA_PENDING":
return {
...state,
checks: []
};
case "FETCH_DATA_SUCCESS":
const { items, pageNumber, pageCount, totalCount } = action.payload;
return {
...state,
checks: items,
pagination: {
...state.pagination,
pageCount,
totalCount,
pageNumber
}
};
case "FETCH_DATA_ERROR":
return {
...state,
checks: [],
pagination: INITIAL_PAGINATION
};
case "SET_FILTER_INPUT":
return {
...state,
filters: {
...state.filters,
...action.payload
}
};
case "SET_FILTER_STATE":
const { status } = action.payload;
return {
...state,
filters: {
...state.filters,
status
}
};
case "CLEAR_FILTERS":
return {
...state,
filters: INITIAL_FILTERS
};
case "SET_PAGE_NUMBER":
return {
...state,
pagination: {
...state.pagination,
pageNumber
}
};
case "RESET_PAGINATION":
return {
...state,
pagination: INITIAL_PAGINATION
};
case "FETCH_STATUSES_SUCCESS":
const { statusList } = action.payload;
return {
...state,
statusList
};
case "FETCH_STATUSES_ERROR":
return {
...state,
statusList: []
};
default:
throw new Error();
}
};
export const Checks = props => {
const [state, dispatch] = useReducer(reducer, initialState);
const {
checks,
pagination: { pageCount, pageNumber },
filters,
filters: { title, сontrolledObject, status },
selectedCheckId,
statusList
} = state;
useEffect(() => {
loadData();
loadStatusList();
}, []);
const loadData = async () => {
try {
const response = await props.api.check.getChecks({
filters: {
title,
сontrolledObject,
status
},
pageNumber,
maxRowCount: ITEMS_PER_PAGE
});
const { items, pageNumber, pageCount, totalCount } = response.data;
dispatch({
type: "FETCH_DATA_SUCCESS",
payload: {
pageNumber,
pageCount,
totalCount,
items: items || []
}
});
} catch (error) {
dispatch({
type: "FETCH_DATA_ERROR"
});
}
};
const loadStatusList = async () => {
try {
const response = await props.api.type.getStatuses({
parentId: STATUSES_PARENT_ID
});
const { items } = response.data;
dispatch({
type: "FETCH_STATUSES_SUCCESS",
payload: {
statusList: items || []
}
});
} catch (error) {
dispatch({
type: "FETCH_STATUSES_ERROR"
});
}
};
const onFilterInputChange = e => {
dispatch({
type: "SET_FILTER_INPUT",
payload: {
[e.target.name]: e.target.value
}
});
};
const onFilterStatusChange = e => {
dispatch({
type: "SET_FILTER_STATE",
payload: {
status
}
});
};
const onFiltersClear = () => {
dispatch({
type: "CLEAR_FILTERS"
});
// loadData
};
const onApplyFilters = () => {
dispatch({
type: "RESET_PAGINATION"
});
// loadData
};
const onPageChange = data => {
dispatch({
type: "SET_PAGE_NUMBER",
payload: {
pageNumber: data.selected + 1
}
});
// loadData
};
const onSort = () => {};
const onOpenUserCard = () => {};
const columns = [
//some columns
];
return (
<div className="checks">
<Filters
onFilterInputChange={onFilterInputChange}
onFilterStatusChange={onFilterStatusChange}
onApplyFilters={onApplyFilters}
onClear={onFiltersClear}
filters={filters}
statusList={statusList}
/>
<Table
columns={columns}
data={checks}
onSort={onSort}
paginated={true}
onPageChange={onPageChange}
pageCount={pageCount}
forcePage={pageNumber}
selectedItemId={selectedCheckId}
/>
<style jsx>{styles}</style>
</div>
);
};
解决方案
使加载函数对过滤器更改做出反应的关键是将过滤器添加到useEffect()
依赖项列表中。
useEffect(() => {
loadData();
loadStatusList();
}, [filters, pageNumber]);
虽然我没有看到loadStatusList()
依赖于过滤器,所以建议将两个异步调用分成它们自己的效果
useEffect(() => {
loadData();
}, [filters, pageNumber]);
useEffect(() => {
loadStatusList();
}, []);
最后,在每次渲染时都会重新创建 load* 函数,因此您可以将它们移动到各自的效果中,或者将它们包装在 中useCallback()
,或者将它们移到组件之外(但是您必须传递所有参数而不是使用闭包)。
useEffect(() => {
const loadData = async () => {
...
});
loadData();
}, [filters]);
useEffect(() => {
const loadStatusList = async () => {
...
});
loadStatusList();
}, []);
我可以从评论中看到您没有连接事件(按钮单击)并且状态发生变化。
副作用,尤其是异步的,必须包含在
useEffect()
.useEffects
仅在状态更改时触发(或 === onMount 的空依赖列表的特殊情况)。由于您只能对状态更改运行效果,因此您必须使事件(按钮单击)更改某些状态,然后在
useEffect()
依赖项列表中使用该状态作为触发器。
因此,在 onFilterInputChange 事件之后
onFilterInputChange
-> dispatch(SET_FILTER_INPUT)
-> reducer sets new value for filters
-> effect has filters as dependency, so it runs
-> loadData called with new filters as parameter
-> on response dispatch(FETCH_DATA_SUCCESS) with new data
我们可能遇到的唯一问题pagerNumber
是效果的输入和输出,因此在更新时可能会出现反馈循环。
为了安全起见,我们可以添加一个控制获取的状态变量
const initialState = {
filters: INITIAL_FILTERS,
checks: [],
pagination: INITIAL_PAGINATION,
selectedCheckId: null,
statusList: [],
doFetch: true // initially true === do a fetch on mount
};
const reducer = (state, action) => {
switch (action.type) {
case "FETCH_DATA_PENDING":
return {
...state,
checks: [],
doFetch: true
};
case "FETCH_DATA_SUCCESS":
const { items, pageNumber, pageCount, totalCount } = action.payload;
return {
...state,
checks: items,
pagination: {
...state.pagination,
pageCount,
totalCount,
pageNumber
},
doFetch: false
};
case "FETCH_DATA_ERROR":
return {
...state,
checks: [],
pagination: INITIAL_PAGINATION,
doFetch: false
};
...
const onFilterInputChange = e => {
dispatch({
type: "SET_FILTER_INPUT",
payload: {
[e.target.name]: e.target.value
}
});
dispatch({type: "FETCH_DATA_PENDING" });
};
const onFilterStatusChange = e => {
dispatch({
type: "SET_FILTER_STATE",
payload: {
status
}
});
dispatch({type: "FETCH_DATA_PENDING" });
};
const onFiltersClear = () => {
dispatch({
type: "CLEAR_FILTERS"
});
dispatch({type: "FETCH_DATA_PENDING" });
};
useEffect(() => {
if (doFetch) {
loadData();
}
}, [doFetch]);
推荐阅读
- python - Appending specific indices from zipped lists
- jsse - Tomcat8不断显示https-jsse-nio-443-exec日志
- php - 如何在 Symfony 3.4 中获取当前页面 URL
- sql - TableCell 数据传递到另一个 UIViewController
- forms - 使用 VeeValidate 的 VueJS 表单验证,无法在某些移动设备上输入
- excel - 5 个特定单元格的平均值,包括活动行上面的 2 个/下面的 2 个跳过空白而不是包含在范围内
- sql - 从 R 将表写入 SAP HANA 的有效方法
- java - POM PageFactory 中需要吸气剂吗?
- java - 使用 GDAA 连接到 Google Drive 时屏幕变暗一秒钟
- angular - 如何在其他中绑定 FormBuilder 输入以将输出 postData 发送到 API?