React Native - 從父組件重新渲染子組件

Question

我正在嘗試修改日歷 - https://github.com/wix/react-native-calendars以便當我按下一天時，背景和文本 colors 會在那天發生變化。 我讀到要重新渲染一個組件，您需要更新父組件的 state，這就是我正在嘗試的：

父類.js

export default class InitiateRent extends Component {
  state = {
    ....
    this.markedDays: {},
    someVar: 0
  };

  constructor() {
    super(); 
    this.handler = this.handler.bind(this);
    this.markedDays = {};
  }

  ....

  handler(e) {
    console.log('handler running');
    this.setState({
      someVar: 123
    })
  }

  <Calendar 
    handler={this.handler}
    markedDates={this.markedDays}
    onDayPress={(day)=> {
      console.log('selected day', day);

      var dateString = `'${day.year}-${day.month}-${day.day}'`

      var addDate = {
        [dateString]: {
          customStyles: {
            container: {
              backgroundColor: '#6de3dc',
            },
            text: {
              color: 'white',
              fontWeight: 'bold'
            },
          },
        }
      }

      this.markedDays = Object.assign(addDate, this.markedDays);

      console.log(this.markedDays);
    }}

....

子.js

pressDay(date) {
    this.props.handler();
    this._handleDayInteraction(date, this.props.onDayPress);
}

renderDay(day, id) { //GETS CALLED IN CHILD RENDER METHOD VIA AN INTERMEDIARY
    ....
        <DayComp
          ....
          onPress={this.pressDay}
          ....
}

一切正常，除了我沒有得到預期的結果 - 當我按日歷上的日期時，處理程序觸發， state 發生變化，並且在控制台中我的 object 看起來正確：

Object

'2018-9-23': {customStyles: {container: {backgroundColor: "#6de3dc"}, text: {color: "white", fontWeight: "bold"}}}

'2018-9-26': {customStyles: {container: {backgroundColor: "#6de3dc"}, text: {color: "white", fontWeight: "bold"}}}

'2018-9-28': {customStyles: {container: {backgroundColor: "#6de3dc"}, text: {color: "white", fontWeight: "bold"}}}

'2018-9-29': {customStyles: {container: {backgroundColor: "#6de3dc"}, text: {color: "white", fontWeight: "bold"}}}

但是日歷上當天的背景沒有改變，文本也沒有改變——我需要做什么才能讓它重新呈現（改變）？

更新

我創建了一系列處理程序，從最底層的day組件開始，它只代表日歷上的一天，一直到最高級的父視圖（不是 App.js，但就在它下面），但仍然什么也沒做。

更新

日歷是模態的，我沒有任何更新其 state 的處理程序，這可能是問題所在嗎？

更新

我在文檔中找到了這個：

.免責聲明。 確保 markedDates 參數是不可變的。 如果您更改 markedDates object 內容但對其的引用未更改，則不會觸發日歷更新。

這是什么意思？

更新

我試圖通過一些谷歌搜索來解釋這意味着什么，這會使this.state.markedDays不可變嗎？：

                const markedDays = this.state.markedDays;

                var dateString = `'${day.year}-${day.month}-${day.day}'`;

                var addDate = {
                  [dateString]: {
                    customStyles: {
                      container: {
                        backgroundColor: '#6de3dc',
                      },
                      text: {
                        color: 'white',
                        fontWeight: 'bold'
                      },
                    },
                  }
                }

                const markedDaysHolder = {
                  ...markedDays,
                  ...addDate
                }
                
                this.state.markedDays = markedDaysHolder;

更新

我放：

componentDidUpdate(prevProps, prevState, snapshot) {
  console.log("componentDidUpdate in InitiateRent:", prevProps, prevState, snapshot);
}

上面的output是：

componentDidUpdate in InitiateRent: (3) (index.bundle, line 761)

{initiateRentMessage: function, modalHeight: 200, modalWidth: 200, handler: function}

{modalVisible: true, message: "Hi, I would like to rent an item from you.", rentButtonBackground: "#6de3dc", someVar: 123, markedDays: Object}

undefined

我可以從這個 output 看到 state object markedDays隨着每次按下按鈕而變大，為什么樣式沒有改變？

在所有相關組件中，我注意到它不會在最低階組件上觸發，這是需要更改的組件。

Answer 1

我也有這個問題，這是你需要做的

constructor(props) {
    super(props)
    this.state = {
    }
    this.onDayPress = this.onDayPress
  }

showCalendar = () => {
    return (
      <Calendar
        onDayPress={this.onDayPress}
        style={styles.calendar}
        hideExtraDays
        markedDates={{
          [this.state.selected]: {
            selected: true,
            disableTouchEvent: true,
            selectedDotColor: 'orange',
          },
        }}
      />
    )
  }

onDayPress = day => {
    this.setState({
      selected: day.dateString,
    })
  }

Answer 2

這是我試圖做的事情的沖洗答案。 我希望能夠通過按下它來選擇和取消選擇日期（在@HaiderAli 幫助之后取消選擇是問題）：

我所要做的就是：

onDayPress = (day) => {
  const _selectedDay = day.dateString;
  let marked = true;
  if (this.state._markedDates[_selectedDay]) {
    // Already in marked dates, so reverse current marked state
    marked = !this.state._markedDates[_selectedDay].selected;
    console.log('marked:', marked);
  }
          
  // Create a new object using object property spread since it should be immutable
  // Reading: https://davidwalsh.name/merge-objects
  const updatedMarkedDates = {
    ...this.state._markedDates,
    ...{
      [_selectedDay]: {
        'selected': marked,
        customStyles: {
          container: {
            backgroundColor: '#6de3dc',
          },
          text: {
            color: 'white',
            fontWeight: 'bold'
          },
        },
      }
    }
  }

  // Triggers component to render again, picking up the new state
  this.setState({ _markedDates: updatedMarkedDates });
}

我添加了'selected': ，它需要在那里，這個功能改進了@HaiderAli 的答案。

為了得到取消選擇工作，開node_modules/react-native-calendars/src/calendar/day/custom/index.js （這是你的錯了文件，如果你不使用markingType={'custom'}支撐上日歷。如果您不使用道具，請編輯node_modules/react-native-calendars/src/calendar/day/basic/index.js ）。 進行此更改：

....

render() {
    let containerStyle = [this.style.base];
    let textStyle = [this.style.text];

    let marking = this.props.marking || {};
    if (marking && marking.constructor === Array && marking.length) {
      marking = {
        marking: true
      };
    }
    const isDisabled = typeof marking.disabled !== 'undefined' ? marking.disabled : this.props.state === 'disabled';

    console.log('marking in day:', marking.selected);

    if (marking.selected) {
      containerStyle.push(this.style.selected);
    } else if (isDisabled) {
      textStyle.push(this.style.disabledText);
    } else if (this.props.state === 'today') {
      containerStyle.push(this.style.today);
      textStyle.push(this.style.todayText);

    /********ADD THIS CONDITION********/
    } else if(!marking.selected) { 
      textStyle.push({backgroundColor: '#ffffff', color: '#2d4150'});
    }

....

Answer 3

import { View, Text, StyleSheet } from 'react-native';
import React, { useState, useEffect } from 'react';
import { Calendar, CalendarList, Agenda } from 'react-native-calendars';

const Calender = () => {
  const [selectedDay, setSelectedDay] = useState();

  return (
    <View style={{ flex: 1, backgroundColor: 'white' }}>
      <Calendar
        style={[styles.calendar, { height: 350 }]}
        onDayPress={(day) => {
          setSelectedDay({ selected: day.dateString });
        }}
        enableSwipeMonths={true}
        markedDates={{
          [selectedDay?.selected]: {
            selected: true,
            disableTouchEvent: true,
            selectedDotColor: 'orange',
          },
        }}
      />
    </View>
  );
};

export default Calender;