属性 更改时如何重新渲染反应组件
How to re-render react component when a property changes
所以我有这个反应组件，下拉列表 属性 (SPFx) 有 2 个值，我需要当下拉列表更改时再次重新呈现反应，下拉列表定义数据源来自将在何处检索值。
Webpart.ts
import * as React from 'react';
import * as ReactDom from 'react-dom';
import { Version } from '@microsoft/sp-core-library';
import {
BaseClientSideWebPart,
IPropertyPaneConfiguration,
PropertyPaneDropdown
} from "@microsoft/sp-webpart-base";
import * as strings from 'AbstractfactoryWebPartStrings';
import Abstractfactory from './components/Abstractfactory';
import { IAbstractFactoryProps } from './components/IAbstractFactoryProps';
import { IAbstractfactoryWebPartProps } from "./IAbstractfactoryWebPartProps";
export default class AbstractfactoryWebPart extends BaseClientSideWebPart<IAbstractfactoryWebPartProps> {
public render(): void {
const element: React.ReactElement<IAbstractFactoryProps > = React.createElement(
Abstractfactory,
{
datasource: this.properties.datasource
}
);
ReactDom.render(element, this.domElement);
}
protected get dataVersion(): Version {
return Version.parse('1.0');
}
protected onPropertyPaneFieldChanged(propertyPath: string, oldValue: any, newValue: any): void {
super.onPropertyPaneFieldChanged(propertyPath, oldValue, newValue);
}
protected getPropertyPaneConfiguration(): IPropertyPaneConfiguration {
return {
pages: [
{
header: {
description: strings.PropertyPaneDescription
},
groups: [
{
groupName: strings.BasicGroupName,
groupFields: [
PropertyPaneDropdown("datasource", {
label: "DataSource",
options: [
{ key: "1", text: "Sharepoint"},
{ key: "2", text: "JSON" }
],
selectedKey: "1",
})
]
}
]
}
]
};
}
}
Component.tsx
import * as React from 'react';
import { IAbstractFactoryProps } from "./IAbstractFactoryProps";
import { IAbstractFactoryState } from "./IAbstractFactoryState";
import styles from './Abstractfactory.module.scss';
import { escape } from '@microsoft/sp-lodash-subset';
import DaoFactory from "./DaoFactory";
import ICustomerDao from "./ICustomerDao";
import DataSources from "./DatasourcesEnum";
export default class Abstractfactory extends React.Component<IAbstractFactoryProps, IAbstractFactoryState> {
//Private instance of customerDao, please note it returns ICustomerDao, an Interface,
//not a concrete type
private customerDao: ICustomerDao;
constructor(props: IAbstractFactoryProps, state: IAbstractFactoryState) {
super(props);
this.setInitialState();
// We set the Dao depending on the selected data source
this.setDaos(props.datasource);
//Then we set the list of customers and note, we dont care if they come from Sharepoint
//Rest API or anything else.
this.state = {
items: this.customerDao.listCustomers(),
};
}
public render(): React.ReactElement<IAbstractFactoryProps> {
return (
<div className={ styles.abstractfactory }>
<div className={ styles.container }>
<div className={ styles.row }>
<div className={ styles.column }>
{this.state.items.map( i => (<div key={i.id}>{i.firstName}</div>))}
</div>
</div>
</div>
</div>
);
}
public setInitialState(): void {
this.state = {
items: []
};
}
private setDaos(datasource: string): void {
const data: DataSources = datasource === "Sharepoint" ? DataSources.SharepointList : DataSources.JsonData;
this.customerDao = DaoFactory.getDAOFactory(data).getCustomerDAO();
//Now, its transparent for us a UI developers what datasource was selected
//this.customerDao.
}
}
州
import Customer from "./Customer";
export interface IAbstractFactoryState {
items?: Customer[];
}
道工厂
import ICustomerDAO from "./ICustomerDAO";
import DataSources from "./DatasourcesEnum";
abstract class DAOFactory {
//For each entity we will need to implement getCustomerDAO, this will make it easily replaceable
//when another datasource comes in
public abstract getCustomerDAO(): ICustomerDAO;
//Static method that receives a parameter depending on the datasource and will return the specifc
//factory
public static getDAOFactory(whichFactory: DataSources): DAOFactory {
switch (whichFactory) {
case DataSources.SharepointList:
return new SharepointListDAOFactory();
case DataSources.JsonData:
return new JsonDAOFactory();
default :
return null;
}
}
}
export default DAOFactory;
import SharepointListDAOFactory from "./SharepointListDAOFactory";
import JsonDAOFactory from "./JsonDAOFactory";
JsonCustomerDao.ts
import ICustomerDao from "./ICustomerDao";
import Customer from "./Customer";
class JsonCustomerDAO implements ICustomerDao{
public insertCustomer(): number {
// implementation to be done by reader
return 1;
}
public deleteCustomer(): boolean {
// implementation to be done by reader
return true;
}
public findCustomer(): Customer {
// implementation to be done by reader
return new Customer();
}
public updateCustomer(): boolean {
// implementation to be done by reader
return true;
}
public listCustomers(): Customer[] {
// implementation to be done by reader
let c1: Customer= new Customer();
let c2: Customer= new Customer();
c1.id="3";
c1.firstName="Andrew";
c1.lastName="Valencia";
c2.id="4";
c2.firstName="Charles";
c2.lastName="Smith";
let list: Array<Customer> = [c1, c2 ];
return list;
}
}
export default JsonCustomerDAO;
SharepointCustomerDao
import ICustomerDao from "./ICustomerDao";
import Customer from "./Customer";
class SharepointCustomerDao implements ICustomerDao {
public insertCustomer(): number {
// implementation to be done by reader
return 1;
}
public deleteCustomer(): boolean {
// implementation to be done by reader
return true;
}
public findCustomer(): Customer {
// implementation to be done by reader
return new Customer();
}
public updateCustomer(): boolean {
// implementation to be done by reader
return true;
}
public listCustomers(): Customer[] {
// implementation to be done by reader
let c1: Customer = new Customer();
c1.id="1";
c1.firstName="Luis";
c1.lastName="Valencia";
let c2: Customer = new Customer();
c2.id="2";
c2.firstName="John";
c2.lastName="Smith";
let list: Array<Customer> = [c1, c2 ];
return list;
}
}
export default SharepointCustomerDao;
第一次执行时，值是为默认数据源呈现的，但是当 属性 发生变化时，UI 不会随着新值而变化。
我发现我可以使用这个事件在下拉列表更改时设置新的道具数据源值
protected onPropertyPaneFieldChanged(propertyPath: string, oldValue: any, newValue: any): void {
this.properties[this.properties.datasource] = newValue;
this.render();
super.onPropertyPaneFieldChanged(propertyPath, oldValue, newValue);
}
但是视图没有重新渲染，当道具改变时，我可以使用任何反应 js 事件重新渲染或重新设置状态吗？
根据数据更改重新呈现组件的 React 方法是更新它的状态。
例如，如果您有一个组件 <Foo />，它包含一个渲染方法来显示它的状态，例如
...
render() {
return(
<div>Hello {this.state.name}</div>
)
}
...
该组件将显示 Hello 并且 state.name
中的任何一个
每次更新给定组件的状态时都会重新渲染。所以在你的情况下，如果你得到新项目，你必须将它们推入状态。一旦发生这种情况，反应 class 将触发其渲染方法并将使用当前状态显示新数据。
为此，您需要一个从组件外部或内部调用的自定义方法。
例如
...
foo(receivesSomething) {
const items = this.state.items;
items.push(receivesSomething);
this.setState({items}); // once a setState is being executed in any component react will make a diff between the current DOM and the ShadowDOM, if something is different then it will trigger a re-render of the affected component
}
...
这篇文章写得很好 http://lucybain.com/blog/2017/react-js-when-to-rerender/ 并且也做了一些解释。我建议您也查看一般的生命周期方法。
更新
比如这样。
class Foo extends React.Component {
constructor(props){
super();
window.someFunction = payload => {
// do whatever you want to do with the payload here
this.setState({ items: payload });
}
}
}
update2
如果您的组件正在侦听/接收道具，您可以使用 componentWillReceiveProps(newProps) 生命周期方法进行反应并在其中更新您的组件状态
所以我有这个反应组件，下拉列表 属性 (SPFx) 有 2 个值，我需要当下拉列表更改时再次重新呈现反应，下拉列表定义数据源来自将在何处检索值。
Webpart.ts
import * as React from 'react';
import * as ReactDom from 'react-dom';
import { Version } from '@microsoft/sp-core-library';
import {
BaseClientSideWebPart,
IPropertyPaneConfiguration,
PropertyPaneDropdown
} from "@microsoft/sp-webpart-base";
import * as strings from 'AbstractfactoryWebPartStrings';
import Abstractfactory from './components/Abstractfactory';
import { IAbstractFactoryProps } from './components/IAbstractFactoryProps';
import { IAbstractfactoryWebPartProps } from "./IAbstractfactoryWebPartProps";
export default class AbstractfactoryWebPart extends BaseClientSideWebPart<IAbstractfactoryWebPartProps> {
public render(): void {
const element: React.ReactElement<IAbstractFactoryProps > = React.createElement(
Abstractfactory,
{
datasource: this.properties.datasource
}
);
ReactDom.render(element, this.domElement);
}
protected get dataVersion(): Version {
return Version.parse('1.0');
}
protected onPropertyPaneFieldChanged(propertyPath: string, oldValue: any, newValue: any): void {
super.onPropertyPaneFieldChanged(propertyPath, oldValue, newValue);
}
protected getPropertyPaneConfiguration(): IPropertyPaneConfiguration {
return {
pages: [
{
header: {
description: strings.PropertyPaneDescription
},
groups: [
{
groupName: strings.BasicGroupName,
groupFields: [
PropertyPaneDropdown("datasource", {
label: "DataSource",
options: [
{ key: "1", text: "Sharepoint"},
{ key: "2", text: "JSON" }
],
selectedKey: "1",
})
]
}
]
}
]
};
}
}
Component.tsx
import * as React from 'react';
import { IAbstractFactoryProps } from "./IAbstractFactoryProps";
import { IAbstractFactoryState } from "./IAbstractFactoryState";
import styles from './Abstractfactory.module.scss';
import { escape } from '@microsoft/sp-lodash-subset';
import DaoFactory from "./DaoFactory";
import ICustomerDao from "./ICustomerDao";
import DataSources from "./DatasourcesEnum";
export default class Abstractfactory extends React.Component<IAbstractFactoryProps, IAbstractFactoryState> {
//Private instance of customerDao, please note it returns ICustomerDao, an Interface,
//not a concrete type
private customerDao: ICustomerDao;
constructor(props: IAbstractFactoryProps, state: IAbstractFactoryState) {
super(props);
this.setInitialState();
// We set the Dao depending on the selected data source
this.setDaos(props.datasource);
//Then we set the list of customers and note, we dont care if they come from Sharepoint
//Rest API or anything else.
this.state = {
items: this.customerDao.listCustomers(),
};
}
public render(): React.ReactElement<IAbstractFactoryProps> {
return (
<div className={ styles.abstractfactory }>
<div className={ styles.container }>
<div className={ styles.row }>
<div className={ styles.column }>
{this.state.items.map( i => (<div key={i.id}>{i.firstName}</div>))}
</div>
</div>
</div>
</div>
);
}
public setInitialState(): void {
this.state = {
items: []
};
}
private setDaos(datasource: string): void {
const data: DataSources = datasource === "Sharepoint" ? DataSources.SharepointList : DataSources.JsonData;
this.customerDao = DaoFactory.getDAOFactory(data).getCustomerDAO();
//Now, its transparent for us a UI developers what datasource was selected
//this.customerDao.
}
}
州
import Customer from "./Customer";
export interface IAbstractFactoryState {
items?: Customer[];
}
道工厂
import ICustomerDAO from "./ICustomerDAO";
import DataSources from "./DatasourcesEnum";
abstract class DAOFactory {
//For each entity we will need to implement getCustomerDAO, this will make it easily replaceable
//when another datasource comes in
public abstract getCustomerDAO(): ICustomerDAO;
//Static method that receives a parameter depending on the datasource and will return the specifc
//factory
public static getDAOFactory(whichFactory: DataSources): DAOFactory {
switch (whichFactory) {
case DataSources.SharepointList:
return new SharepointListDAOFactory();
case DataSources.JsonData:
return new JsonDAOFactory();
default :
return null;
}
}
}
export default DAOFactory;
import SharepointListDAOFactory from "./SharepointListDAOFactory";
import JsonDAOFactory from "./JsonDAOFactory";
JsonCustomerDao.ts
import ICustomerDao from "./ICustomerDao";
import Customer from "./Customer";
class JsonCustomerDAO implements ICustomerDao{
public insertCustomer(): number {
// implementation to be done by reader
return 1;
}
public deleteCustomer(): boolean {
// implementation to be done by reader
return true;
}
public findCustomer(): Customer {
// implementation to be done by reader
return new Customer();
}
public updateCustomer(): boolean {
// implementation to be done by reader
return true;
}
public listCustomers(): Customer[] {
// implementation to be done by reader
let c1: Customer= new Customer();
let c2: Customer= new Customer();
c1.id="3";
c1.firstName="Andrew";
c1.lastName="Valencia";
c2.id="4";
c2.firstName="Charles";
c2.lastName="Smith";
let list: Array<Customer> = [c1, c2 ];
return list;
}
}
export default JsonCustomerDAO;
SharepointCustomerDao
import ICustomerDao from "./ICustomerDao";
import Customer from "./Customer";
class SharepointCustomerDao implements ICustomerDao {
public insertCustomer(): number {
// implementation to be done by reader
return 1;
}
public deleteCustomer(): boolean {
// implementation to be done by reader
return true;
}
public findCustomer(): Customer {
// implementation to be done by reader
return new Customer();
}
public updateCustomer(): boolean {
// implementation to be done by reader
return true;
}
public listCustomers(): Customer[] {
// implementation to be done by reader
let c1: Customer = new Customer();
c1.id="1";
c1.firstName="Luis";
c1.lastName="Valencia";
let c2: Customer = new Customer();
c2.id="2";
c2.firstName="John";
c2.lastName="Smith";
let list: Array<Customer> = [c1, c2 ];
return list;
}
}
export default SharepointCustomerDao;
第一次执行时，值是为默认数据源呈现的，但是当 属性 发生变化时，UI 不会随着新值而变化。
我发现我可以使用这个事件在下拉列表更改时设置新的道具数据源值
protected onPropertyPaneFieldChanged(propertyPath: string, oldValue: any, newValue: any): void {
this.properties[this.properties.datasource] = newValue;
this.render();
super.onPropertyPaneFieldChanged(propertyPath, oldValue, newValue);
}
但是视图没有重新渲染，当道具改变时，我可以使用任何反应 js 事件重新渲染或重新设置状态吗？
根据数据更改重新呈现组件的 React 方法是更新它的状态。
例如，如果您有一个组件 <Foo />，它包含一个渲染方法来显示它的状态，例如
...
render() {
return(
<div>Hello {this.state.name}</div>
)
}
...
该组件将显示 Hello 并且 state.name
中的任何一个每次更新给定组件的状态时都会重新渲染。所以在你的情况下，如果你得到新项目，你必须将它们推入状态。一旦发生这种情况，反应 class 将触发其渲染方法并将使用当前状态显示新数据。
为此，您需要一个从组件外部或内部调用的自定义方法。
例如
...
foo(receivesSomething) {
const items = this.state.items;
items.push(receivesSomething);
this.setState({items}); // once a setState is being executed in any component react will make a diff between the current DOM and the ShadowDOM, if something is different then it will trigger a re-render of the affected component
}
...
这篇文章写得很好 http://lucybain.com/blog/2017/react-js-when-to-rerender/ 并且也做了一些解释。我建议您也查看一般的生命周期方法。
更新
比如这样。
class Foo extends React.Component {
constructor(props){
super();
window.someFunction = payload => {
// do whatever you want to do with the payload here
this.setState({ items: payload });
}
}
}
update2
如果您的组件正在侦听/接收道具，您可以使用 componentWillReceiveProps(newProps) 生命周期方法进行反应并在其中更新您的组件状态