上下文

Question

我在开发应用程序，用钩子，我被卡住了。

我不知道为什么，但我的组件没有从我的上下文组件下载状态，或者我的初始状态没有正确更新。贝娄，我插入了几个截图从我的应用程序。

上下文组件

import React, { createContext, useState } from 'react';

export const WeatherDataContext = createContext();

const WeatherDataContextProvider = (props) => {
    const [weather, setWeather] = useState(
        {
            city: null,
            temp: null
        }
    )
    const addWeather = (city, temp) => {
        setWeather({
            city,
            temp
        })
    }
    
    return (
        <WeatherDataContext.Provider value={{weather, addWeather}}>
            {props.children}
        </WeatherDataContext.Provider>
    )
}

export default WeatherDataContextProvider

表单- axios -组件：

import React, {useContext, useState} from 'react';
import { WeatherDataContext } from '../context/WeatherDataContext';
import axios from 'axios'
import {Link} from 'react-router-dom'


const WeatherForm = () => {
    const {addWeather} = useContext(WeatherDataContext);
    const [value, setValue] = useState('')

    const handleChange = (e) => {
        e.preventDefault();
        axios.get(`https://api.openweathermap.org/data/2.5/weather?q=${value}&appid=${KEY}&units=metric`)
            .then(res => {
                
                
               addWeather(res.data.name, res.data.main.temp)
                
            })
      
    }

    return (
        <div class='weather-form'>
            <form onSubmit={handleChange}>
                <input placeholder='City' onChange={(e) => setValue(e.target.value)} value={value} required/>
                <Link to='/weather'><button>Search</button></Link>
                
            </form>
        </div>
    )
}

export default WeatherForm

和我想使用更新状态的最后一个组件

import React, {useContext, useState} from 'react';
import { WeatherDataContext } from '../context/WeatherDataContext';

const WeatherFront = () => {
    const {weather} = useContext(WeatherDataContext)
    
    console.log(weather)
    return (
        <div class='weather-front'>
            <h1>City: {weather.city}, Temperatura: {weather.temp}</h1>
        </div>
    )
}

export default WeatherFront

Answer 1

问题可能是你没有提交表格。

 <Link to='/weather'><button>Search</button></Link>

只需导航到WeatherFront。

你可以试试

import { useHistory } from "react-router-dom";
...
const WeatherForm = () => {
    const history = useHistory()
    const {addWeather} = useContext(WeatherDataContext)
    const [value, setValue] = useState('')

    const handleChange = (e) => {
        e.preventDefault();
        axios.get(`https://api.openweathermap.org/data/2.5/weather?q=${value}&appid=${KEY}&units=metric`)
            .then(res => {
               addWeather(res.data.name, res.data.main.temp)
               history.push('/weather')
            })
      
    }

    return (
        <div class='weather-form'>
            <form onSubmit={handleChange}>
                <input placeholder='City' onChange={(e) => setValue(e.target.value)} value={value} required/>
                <input type="submit" value="Search" />
            </form>
        </div>
    )
}