I have simply react weather app where I select a city from and after it, I need to reload the data. Basically, it's working fine. But after the change of the city, my child components shows new data, old data, and repeat it a few times, and after it, components show good data. What's wrong?
I try to implement some functions from component lifecycle methods, but it didn't work.
import React, { Component } from 'react';
import './App.css';
import Form from "./Components/Form"
import Overcast from "./Components/Overcast"
import Forecast from "./Components/Forecast"
class App extends Component {
constructor(props) {
super()
this.state = {
forecasts: [{}],
selectedCity: 1
}
this.handleCityChange = this.handleCityChange.bind(this)
this.fetchForeacst = this.fetchForeacst.bind(this)
}
componentDidMount() {
var today = new Date()
var day = String(today.getDate()).padStart(2, '0')
var month = String(today.getMonth() + 1).padStart(2, '0')
var year = String(today.getFullYear())
today = year + '-' + month + '-' + day
this.fetchForeacst(today)
}
componentDidUpdate() {
var today = new Date()
var day = String(today.getDate()).padStart(2, '0')
var month = String(today.getMonth() + 1).padStart(2, '0')
var year = String(today.getFullYear())
today = year + '-' + month + '-' + day
this.fetchForeacst(today)
}
fetchForeacst(date) {
const WEATHER_API = 'http://dev-weather-api.azurewebsites.net/api/city/' + this.state.selectedCity + '/weather?date=' + date + ''
fetch(WEATHER_API)
.then(response => response.json())
.then(data => this.setState({forecasts: data}))
}
handleCityChange(city) {
this.setState({selectedCity: city})
}
render() {
return (
<div className="App">
<Form handleChange={this.handleCityChange}/>
<Overcast forecast={this.state.forecasts[0]} />
<Forecast forecasts={this.state.forecasts} />
</div>
)
}
}
export default App;
I don't have any errors or something.
You call the fetch api on didUpdate, which triggers a setState, which calls didUpdate again and again. That's why you see the loop. You should wrap the fetch in an if statement like this:
componentDidUpdate(prevProps, prevState) {
if(prevState.selectedCity !== this.state.selectedCity) {
var today = new Date()
var day = String(today.getDate()).padStart(2, '0')
var month = String(today.getMonth() + 1).padStart(2, '0')
var year = String(today.getFullYear())
today = year + '-' + month + '-' + day
this.fetchForeacst(today)
}
}
Hope this helps. Happy coding.
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