Component's prop doesn't update in React Native with Redux - react-native

Question

I need some help with my app and Redux! (Currently, i hate it aha)
So, i have a notification page component which fetch some datas and i need to put the data length into my redux store to put badge on my icon in my tabbar!
My Main Reducer :
import { combineReducers } from "redux";
import NotificationReducer from "./NotificationReducer";
export default function getRootReducer(navReducer) {
return combineReducers({
nav: navReducer,
notificationReducer: NotificationReducer
});
}
My Notification reducer
const initialState = {
NotificationCount: 0
};
export default function notifications(state = initialState, action = {}) {
switch (action.type) {
case 'SET_COUNT' :
console.log('REDUCER NOTIFICATION SET_COUNT',state)
return {
...state,
NotificationCount: action.payload
};
default:
return state;
}
};
My Action :
export function setNotificationCount(count) {
return function (dispatch, getState) {
console.log('Action - setNotificationCount: '+count)
dispatch( {
type: 'SET_COUNT',
payload: count,
});
};
};
My Component :
import React, { Component } from 'react';
import { View, Text, StyleSheet, ScrollView, Dimensions, TouchableOpacity, SectionList, Alert } from 'react-native';
import Icon from 'react-native-vector-icons/Ionicons';
import { Notification } from '#Components';
import { ORANGE } from '#Theme/colors';
import { NotificationService } from '#Services';
import Style from './style';
import { connect } from 'react-redux';
import { bindActionCreators } from 'redux';
import * as Actions from '#Redux/Actions';
const width = Dimensions.get('window').width
const height = Dimensions.get('window').height
export class NotificationsClass extends Component {
constructor(props) {
super(props);
this.state = {
dataSource: [],
NotificationCount: undefined
};
}
async componentWillMount() {
this.updateNotifications();
}
componentWillReceiveProps(nextProps){
console.log('receive new props',nextProps);
}
async updateNotifications() {
this.props.setNotificationCount(10); <---
let data = await NotificationService.get();
if (data && data.data.length > 0) {
this.setState({ dataSource: data });
console.log(this.props) <-- NotificationCount is undefined
}
}
render() {
if (this.state.dataSource.length > 0) {
return (
<SectionList
stickySectionHeadersEnabled
refreshing
keyExtractor={(item, index) => item.notificationId}
style={Style.container}
sections={this.state.dataSource}
renderItem={({ item }) => this.renderRow(item)}
renderSectionHeader={({ section }) => this.renderSection(section)}
/>
);
} else {
return this.renderEmpty();
}
}
renderRow(data) {
return (
<TouchableOpacity activeOpacity={0.8} key={data.notificationId}>
<Notification data={data} />
</TouchableOpacity>
);
}
}
const Notifications = connect(
state => ({
NotificationCount: state.NotificationCount
}),
dispatch => bindActionCreators(Actions, dispatch)
)(NotificationsClass);
export { Notifications };
(I've removed some useless code)
Top Level :
const navReducer = (state, action) => {
const newState = AppNavigator.router.getStateForAction(action, state);
return newState || state;
};
#connect(state => ({
nav: state.nav
}))
class AppWithNavigationState extends Component {
render() {
return (
<AppNavigator
navigation={addNavigationHelpers({
dispatch: this.props.dispatch,
state: this.props.nav,
})}
/>
);
}
}
const store = getStore(navReducer);
export default function NCAP() {
return (
<Provider store={store}>
<AppWithNavigationState />
</Provider>
);
}
React : 15.6.1
React-Native : 0.46.4
Redux : 3.7.2
React-Redux : 5.0.5
React-Navigation : 1.0.0-beta.11
Node : 6.9.1
So if you've an idea! It will be great :D !
Thanks !

Answer 1

There's three issues.
First, React's re-rendering is almost always asynchronous. In updateNotifications(), you are calling this.props.setNotificationCount(10), but attempting to view/use the props later in that function. Even with the await in there, there's no guarantee that this.props.NotificationCount will have been updated yet.
Second, based on your reducer structure and mapState function, props.NotificationCount will actually never exist. In your getRootReducer() function, you have:
return combineReducers({
nav: navReducer,
notificationReducer: NotificationReducer
});
That means your root state will be state.nav and state.notificationReducer. But, in your mapState function, you have:
state => ({
NotificationCount: state.NotificationCount
}),
state.NotificationCount will never exist, because you didn't use that key name when you called combineReducers.
Third, your notificationReducer actually has a nested value. It's returning {NotificationCount : 0}.
So, the value you actually want is really at state.notificationReducer.NotificationCount. That means your mapState function should actually be:
state => ({
NotificationCount: state.notificationReducer.NotificationCount
}),
If your notificationReducer isn't actually going to store any other values, I'd suggest simplifying it so that it's just storing the number, not the number inside of an object. I'd also suggest removing the word Reducer from your state slice name. That way, you could reference state.notification instead.
For more info, see the Structuring Reducers - Using combineReducers section of the Redux docs, which goes into more detail on how using combineReducers defines your state shape.