React Native component rendering twice yet renderItem does not update values?

Question

I am attempting to populate a FlatList of custom components (<EventCard>) on a screen, however, none of the elements of the components are showing up. Ex: The titlein my component is blank, rather than "Test Event" as shown in the terminal output.

Inside componentWillMount() I query my database to populate an array which is then used in renderItem to populate the FlatList

Terminal output shows an initial render() with an empty array and then a second render() with the data.

My guess is that the components are trying to pull from the empty array, thus causing them to be empty. I am confused though because a second call to render() is being logged, so won't the component be rendered again as well? with the full array?

After doing some research, I think I may need to call forceUpdate() or something similar to grab the updated data from the array. I have also tried messing around with componentWillReceiveProps() but I can't get that working either (Source). To be honest, I am not certain on my use of renderItem, this could be contributing to my problem.

I haven't included EventCard.js as I am quite certain it is not the source of the error but I can upon request.

18:00:16: RENDER
18:00:16: Array []
18:00:17: RENDER
18:00:17: Array [
18:00:17:   Object {
18:00:17:     "date": "Fri Dec 07 2018",
18:00:17:     "host": "Test host",
18:00:17:     "key": "-L4mE_YKKbrvaMVNaA2T",
18:00:17:     "location": "",
18:00:17:     "time": "08:30",
18:00:17:     "title": "Test event",
18:00:17:     "volunteersHave": 1,
18:00:17:     "volunteersNeed": "20",
18:00:17:   },
18:00:17: ]

The relevant file, Dashboard.js

import React from 'react';
import { Button, FlatList, StyleSheet, Text, View} from 'react-native';
import { Icon } from 'react-native-elements';
import EventCard from './EventCard';    
import * as firebase from 'firebase';

export default class Dashboard extends React.Component {
    constructor(props){
        super(props)
        this.state = {
            eventArr: [],
        }
    }

    componentWillMount = () => {
        var tempArr = [];
        firebase.database().ref('/events/').once('value').then((snapshot) => {
            tempArr = this.snapshotToArray(snapshot);
            this.setState({
                eventArr: tempArr
            });
        });
    }

    snapshotToArray = snapshot => {
        var retArr = [];
        snapshot.forEach(childSnapshot => {
            var item = childSnapshot.val();
            item.key = childSnapshot.key;
            retArr.push(item);
        });
        return retArr;
    };

    render(){
        console.log('RENDER')
        console.log(this.state.eventArr)
        return (
            <View>
                <FlatList
                    data={this.state.eventArr}
                    renderItem={({item}) =>
                        <EventCard>
                            title={item.title}
                            date={item.date}
                            location={item.location}
                            rsvp={item.volunteersHave}
                            time={item.time}
                            onPress={() => navigate('EventPage')}
                        </EventCard>}
                />
            </View>
        );
    }
}
//styles omitted
const styles = StyleSheet.create({
});

Answer 1

You are wrapping the parameters in wrong way

You should try this:

<EventCard
    title={item.title}
    date={item.date}
    location={item.location}
    rsvp={item.volunteersHave}
    time={item.time}
    onPress={() => navigate('EventPage')}
/>

Answer 2

I think your problem is with your renderItem function. Specifically, you have all your props outside of the EventCard

<EventCard>
    title={item.title}
    date={item.date}
    location={item.location}
    rsvp={item.volunteersHave}
    time={item.time}
    onPress={() => navigate('EventPage')}
</EventCard>

Should be

<EventCard
    title={item.title}
    date={item.date}
    location={item.location}
    rsvp={item.volunteersHave}
    time={item.time}
    onPress={() => navigate('EventPage')}> 
</EventCard>