使用Hook更新上下文状态值

Posted 2021-04-10

我试图跟随this guide关于“如何使用基本反应钩子上下文”，它很擅长为上下文组件提供基本结构，但没有考虑如何在没有返回默认值的情况下更新片段。

我试图实现这样的事情

import React, { Component, useContext, useState } from 'react';

export const ProfileContext = React.createContext<ContextState | null>(null);

interface ContextState {
  changeInformation: Function
  team: string
  company: string
}

export const ProfileProvider = (props) => {
  const userInformation = {
    company: 'Progress',
    companyImage: 'https://svgshare.com/i/9ir.svg',
    url: 'https://www.telerik.com/kendo-react-ui/',
    userImage: 'https://i.imgur.com/Y1XRKLf.png',
    userName: 'Kendoken',
    fullName: 'Kendoken No Michi',
    team: 'KendoReact',
    // This sets all the initial values but changes the team.
    // I want to make a function that changes any property by name to the new value
    changeInformation: (property: string, value: any) => {
      let newInfo = {...userInfo}
      newInfo[property] = value
      setUserInfo(newInfo);
    }
  }

  // create `userInfo` with update method called `setUserInfo`
  // set default to `userInformation`
  const [userInfo, setUserInfo] = useState(userInformation);
  return (
    <ProfileContext.Provider value={userInfo}>
      {props.children}
    </ProfileContext.Provider>
  )
}

出于某种原因，在多次更新后，默认值将返回而不是更新状态。我的子组件看起来像这样：

import React, { useContext } from 'react';
import { ProfileContext } from "../data"

export const ChangeTeam = () => {
    const context = useContext(ProfileContext);
    return (
      <>
        <button className="profile-button"
          onClick={() => context.changeInformation('team', 'Vue')}>Vue</button>
        <button className="profile-button"
          onClick={() => context.changeInformation('company', 'React')}>React</button>
        <p>Team: {context.team}</p>
        <p>Company: {context.company}</p>
      </>
    )
  }

我知道我做错了让它回想起默认值，但我不确定修复它的结构。

如果您有任何见解，请告诉我。

更新 - （我知道价值观是不同的）我已经得到了这个以满足我的需求，但我觉得应该有一个更清洁的方法来管理这个：

import React, { Component, useContext, useState, useEffect } from 'react';

export const ProfileContext = React.createContext<ContextState | null>(null);

interface ContextState {
    setCompany: Function
    setName: Function
    name: string
    company: string
}

export const ProfileProvider = (props: {children: htmlElement}) => {
  const [company, setCompany] = useState('Progress');
  const [name, setName] = useState('Bill');

  return (
    <ProfileContext.Provider value={{company, setCompany, name, setName}}>
      {props.children}
    </ProfileContext.Provider>
  )
}

我希望能够动态地将未知项添加到状态，这就是为什么第一种方法似乎稍微好一点但我不确定的原因。

干杯，

答案

我做了这个似乎工作：

import React, { Component, useContext, useState, useEffect } from 'react';

export const ProfileContext = React.createContext<ContextState | null>(null);

interface ContextState {
  changeInformation: Function
  team: string
  company: string
  address: string
}

export const ProfileProvider = (props: {children: HTMLElement}) => {
  const userInformation = {
    company: 'Progress',
    companyImage: 'https://svgshare.com/i/9ir.svg',
    url: 'https://www.telerik.com/kendo-react-ui/',
    userImage: 'https://i.imgur.com/Y1XRKLf.png',
    userName: 'Kendoken',
    fullName: 'Kendoken No Michi',
    team: 'KendoReact',
    // This sets all the initial values but changes the team.
    // I want to make a function that changes any property by name to the new value
    changeInformation: (property: string, value: any) => {
      setUserInfo(prevInfo => ({
        ...prevInfo,
        [property]: value
      }) );
    }
  }

  // create `userInfo` with update method called `setUserInfo`
  // set default to `userInformation`
  const [userInfo, setUserInfo] = useState(userInformation)

  return (
    <ProfileContext.Provider value={userInfo}>
      {props.children}
    </ProfileContext.Provider>
  )
}

它似乎与演示完全一样，但出于某种原因，我无法让演示工作。我认为这是因为我将它设置为prevInfo。

另一答案

看起来你已经解决了你的问题，但我可以建议稍微改造一下吗？理想情况下（对我而言）你会保持你的数据纯净，我认为没有理由在那里有更新功能。

export const ProfileProvider = (props: { children: HTMLElement }) => {
  const userInformation = {
    company: 'Progress',
    companyImage: 'https://svgshare.com/i/9ir.svg',
  };

  const [userInfo, setUserInfo] = useState(userInformation)

  const changeInfo = (property: string, value: any) =>
    setUserInfo(prevInfo => ({ ...prevInfo, [property]: value }));

  return (
    <ProfileContext.Provider value={{ userInfo, changeInfo }}>
      {props.children}
    </ProfileContext.Provider>
  )
}

export const ChangeTeam = () => {
  const { userInfo, changeInfo } = useContext(ProfileContext);
  return (
    <>
      <button className="profile-button"
        onClick={() => changeInfo('team', 'Vue')}>Vue</button>
      <p>Team: {userInfo.team}</p>
    </>
  )
}