Develop Reference

React Native Carousel UseState

I am currently implementing a carousel library (react-native-reanimated-carousel). The code for the following is represented as such:
<Carousel
width={cardWidth}
height={cardHeight}
data={cards}
onScrollEnd={() => {console.log('ended')}}
renderItem={({item}) =>
(
<View>
<Image
source={{uri: item["ImgURL"],}}
style={styles.card}
/>
</View>
)}
/>
Upon the carousel changing, the item value in the renderItem property changes. Is there a way to get the value of item from outside this element? I want other elements outside to change depending on the value (and properties) of item.

You could try to call a callback function in the renderItem function.
() => {
const [activeItem, setActiveItem] = useState(cards[0].item);
return (<Carousel
width={cardWidth}
height={cardHeight}
data={cards}
onScrollEnd={() => {console.log('ended')}}
renderItem={({item}) => {
setActiveItem(item);
return (
<View>
<Image
source={{uri: item["ImgURL"],}}
style={styles.card}
/>
</View>
);
}}
/>)
);
};
Or you could use onScrollEnd. It provides the previous index and the current index according to the documentation
() => {
const [activeItem, setActiveItem] = useState(cards[0].item);
return (<Carousel
width={cardWidth}
height={cardHeight}
data={cards}
onScrollEnd={(previous, current) => {
setActiveItem(cards[current].item);
console.log('ended')
}}
renderItem={({item}) => (
<View>
<Image
source={{uri: item["ImgURL"],}}
style={styles.card}
/>
</View>
)}
/>)
);
};
Or you could use the Ref prop getCurrentIndex

React Native: renderItem component to Custom FlatList as a prop? (like Vue slots)

I want to have a reusable FlatList component, basically a wrapper I can pass a custom component as an item to render, and I want to pass this component as props, this is easily done in vue..js with scoped/slots.
Is there a way to do this in react native?
<View style={{ flex:1 }}>
<FlatList style={{ width:'100%'}} data={props.data} keyExtractor={item => item.id.toString()}
renderItem={({ item, index }) =>
<PropComponent item={item}></PropComponent>}
/>
</View>
In example above PropComponent would be passed to CustomFlatList like this:
<CustomFlatList>
<PropComponent></PropComponent>
</CustomFlatList>
```

Use this way
// CustomFlatList.js
const { ...rest } = props;
<View style={{ flex:1 }}>
<FlatList
style={{ width:'100%'}}
data={props.data}
keyExtractor={item => item.id.toString()}
{...rest}
/>
</View>
Usage like
itemView = ({ item, index }) => {
return <PropComponent item={item} />
}
<CustomFlatList renderItem={itemView} />

How to pass a function/method as a parameter in react navigation.navigate

I have two components named Home.js and ViewList.js the user can navigate to each component using a stack navigator.
I want to pass the updatePrice function as a parameter from Home.js to ViewList.js below are snippets on what I am attempting to accomplish.
Here is a brief description of how the app is suppose to work. The user navigates from the Home.js component
to the ViewList.js component. In the View.js component the user has the ability to enter a price for the item.
onChangeText I want to run the updatePrice function so that I can update the state of the list item in the Home.js component.
My problem is that I cannot seem to figure out how to pass the updatePrice function to the ViewList through. Any suggestions
on how I can accomplish this ?
Below is a code snippet for Home.js
export default function Home({navigation}){
const updatePrice = (key, id, price) =>{
setShoppingList(list =>
list.map(list =>
list.key === key
? {
...list,
listItems: list.listItems.map(item =>
item.id === id
? {
...item,
price
}
:item
)
}
: list
)
)
console.log(shoppingLists);
}
return(
<View style={globalStyles.container}>
<FlatList
data={shoppingLists}
renderItem={({ item }) =>(
<TouchableOpacity onPress={() =>
// Here I try to pass the function through the
//navigate prop as an object.
navigation.navigate('ViewList',item,{'updatePrice': () => this.updatePrice})}>
{/*Create card container to wrap text in*/}
<Card>
<Text>{item.name}</Text>
<Text>Budget: $ {item.budget}</Text>
</Card>
</TouchableOpacity>
)}
keyExtractor={item => item.key}
/>
</View>
)
}
Here is another ViewList.js
export default function ViewList({navigation}){
const shoppingListKey = navigation.getParam('key');
const updatePrice = navigation.getParam('updatePrice');
const listInfo = navigation.getParam('listItems');
return(
<View style={globalStyles.container}>
<Card>
<Text>{navigation.getParam('name')}</Text>
<Text>Budget: $ {budget}</Text>
<Text> Total: {total}</Text>
<FlatList
data={listInfo}
renderItem={({item}) =>(
<View>
<Text>{item.name}</Text>
<Text>Price: {item.price}</Text>
<TextInput
style={globalStyles.globalTextInput}
keyboardType={'numeric'}
onChangeText={(value) =>
//Here I try to retrieve the updatePrice function but I got an error.
this.props.navigation.state.params.updatePrice(shoppingListKey,item.id,value)}
/>
</View>
)}
keyExtractor={item => item.id}
/>
</Card>
</View>
)
}

React-Native another VirtualizedList-backed container

After upgrading to react-native 0.61 i get a lot of warnings like that:
VirtualizedLists should never be nested inside plain ScrollViews with the same orientation - use another VirtualizedList-backed container instead.
What is the other VirtualizedList-backed container that i should use, and why is it now advised not to use like that?

If someone's still looking for a suggestion to the problem that #Ponleu and #David Schilling have described here (regarding content that goes above the FlatList), then this is the approach I took:
<SafeAreaView style={{flex: 1}}>
<FlatList
data={data}
ListHeaderComponent={ContentThatGoesAboveTheFlatList}
ListFooterComponent={ContentThatGoesBelowTheFlatList} />
</SafeAreaView>
You can read more about this here: https://facebook.github.io/react-native/docs/flatlist#listheadercomponent
Hopefully it helps someone. :)

Just in case this helps someone, this is how I fixed the error in my case.
I had a FlatList nested inside a ScrollView:
render() {
return (
<ScrollView>
<Text>{'My Title'}</Text>
<FlatList
data={this.state.myData}
renderItem={({ item }) => {
return <p>{item.name}</p>;
}}
/>
{this.state.loading && <Text>{'Loading...'}</Text>}
</ScrollView>
);
}
and I got rid of the ScrollView by using the FlatList to render everything I needed, which got rid of the warning:
render() {
const getHeader = () => {
return <Text>{'My Title'}</Text>;
};
const getFooter = () => {
if (this.state.loading) {
return null;
}
return <Text>{'Loading...'}</Text>;
};
return (
<FlatList
data={this.state.myData}
renderItem={({ item }) => {
return <p>{item.name}</p>;
}}
ListHeaderComponent={getHeader}
ListFooterComponent={getFooter}
/>
);
}

The best way is to disable that warning because sometimes Flatlist need to be in ScrollView.
UPDATE RN V0.63 ABOVE
YellowBox is now changed and replace with LogBox
FUNCTIONAL
import React, { useEffect } from 'react';
import { LogBox } from 'react-native';
useEffect(() => {
LogBox.ignoreLogs(['VirtualizedLists should never be nested']);
}, [])
CLASS BASED
import React from 'react';
import { LogBox } from 'react-native';
componentDidMount() {
LogBox.ignoreLogs(['VirtualizedLists should never be nested']);
}
UPDATE RN V0.63 BELOW
FUNCTIONAL
import React, { useEffect } from 'react';
import { YellowBox } from 'react-native';
useEffect(() => {
YellowBox.ignoreWarnings(['VirtualizedLists should never be nested']);
}, [])
CLASS BASED
import React from 'react';
import { YellowBox } from 'react-native';
componentDidMount() {
YellowBox.ignoreWarnings(['VirtualizedLists should never be nested']);
}

Data
// dummy data array
const data = [
{id: 1, name: 'Tom'},
{id: 2, name: 'Jerry'},
]
Solution #1
You can make a custom component for that like this
const VirtualizedList = ({children}) => {
return (
<FlatList
data={[]}
keyExtractor={() => "key"}
renderItem={null}
ListHeaderComponent={
<>{children}</>
}
/>
)
}
then use this VirtualizedList as parent component:
...
return (
<VirtualizedList>
<FlatList
data={data}
keyExtractor={(item, index) => item.id + index.toString()}
renderItem={_renderItem}
/>
<AnyComponent/>
</VirtualizedList>
)
Solution #2
If you use FlatList inside the ScrollView it gives warning which is annoying, so you can use array's map property, like this -
NOTE: It is not recommended way to show list. If you have small amount of that then you can use it that's totally fine, but if you want to show a list which get data from api and have lot's of data then you can go with other solutions. if you use map with large data then it affect your app performance
<ScrollView>
{data.map((item, index) => (
<View key={index}>
<Text>{item.name}</Text>
</View>
))}
</ScrollView>
Solution #3
if you make your FlatList horizontal (as per your need) then also warning will disappear
<ScrollView>
<FlatList
data={data}
keyExtractor={(item, index) => item.id + index.toString()}
horizontal={true}
/>
</ScrollView>
Solution #4
you can add header and footer component
In ListHeaderComponent and ListFooterComponent you can add any component so you don't need parent ScrollView
<FlatList
data={data}
keyExtractor={(item, index) => item.id + index.toString()}
ListHeaderComponent={headerComponent}
ListFooterComponent={footerComponent}
ListEmptyComponent={emptyComponent}
ItemSeparatorComponent={separator}
/>
// List components
const headerComponent = () => (
<View>
<Header/>
<Any/>
</View>
)
const footerComponent = () => (
<View>
<Footer/>
<Any/>
</View>
)
const emptyComponent = () => (
<View>
<EmptyView/>
<Any/>
</View>
)
const separator = () => (
<View style={{height: 0.8, width: '100%', backgroundColor: '#fff'}} />
)

The warning appears because ScrollView and FlatList share the same logic, if FlatList run inside ScrollView, it's duplicated
By the way SafeAreaView doesn't work for me, the only way to solve is
<ScrollView>
{data.map((item, index) => {
...your code
}}
</ScrollView>
The error disappears

Looking at the examples in docs I've changed container from:
<ScrollView>
<FlatList ... />
</ScrollView>
to:
<SafeAreaView style={{flex: 1}}>
<FlatList ... />
</SafeAreaView>
and all those warnings disappeared.

In my case, I needed to have FlatLists nested in a ScrollView because I am using react-native-draggable-flatlist to move ingredients and steps around in a recipe.
If we read the warning properly, it says that we should use another VirtualizedList-backed container to nest our child FlatList in. What I did is:
/* outside the component */
const emptyArry = []
/* render */
<FlatList
scrollEnabled={false}
horizontal
data={emptyArray}
ListEmptyComponent=(<DraggableList />)
/>
No more warning, and I think this is the pattern recommended by the warning.

<ScrollView horizontal={false} style={{width: '100%', height: '100%'}}>
<ScrollView horizontal={true} style={{width: '100%', height: '100%'}}>
<FlatList ... />
</ScrollView>
</ScrollView>

Below code works perfectly for me to disable annoying error:
VirtualizedLists should never be nested inside plain ScrollViews with the same orientation because it can break windowing and other functionality - use another VirtualizedList-backed container instead.
React Native 0.68.2
<ScrollView horizontal={false} style={{flex: 1}}>
<ScrollView
horizontal={true}
contentContainerStyle={{width: '100%', height: '100%'}}>
<FlatList ... />
</ScrollView>
</ScrollView>

I tried some ways to solve this, including ListHeaderComponent or ListFooterComponent, but it all didn't fit for me.
layout I wanted to achieve is like this, and I wanted to get scrolled in once.
<ScrollView>
<View>I'm the first view</View>
<View>I'm the second view</View>
<MyFlatList />
</ScrollView>
First I want to say thanks to this issue and comments, which gave me bunch of ideas.
I was thinking of ListHeaderComponent places above the Flatlist, but since my Flatlist's direction was column, the header I wanted to place went on the left of the Flatlist :(
Then I had to try on VirtualizedList-backed thing. I just tried to pack all components in VirtualizedList, where renderItems gives index and there I could pass components conditionally to renderItems.
I could have worked this with Flatlist, but I haven't tried yet.
Finally it looks like this.
<View>
<Virtualizedlist
data={[]}
initialNumToRender={1}
renderItem={(props)=>{
props.index===0 ? (1st view here) : props.index===1 ? (2nd view here) : (my flatlist)
}}
keyExtractor={item => item.key}
getItemCount={2}
getItem={ (data, index) => {
return {
id: Math.random().toString(12).substring(0),
}
}}
/>
</View>
(inside which lazyly renders↓)
<View>I'm the first view</View>
<View>I'm the second view</View>
<MyFlatList />
and of course able to scroll the whole screen.

As #Brahim stated above, setting the horizontal property to true seem to resolve the issues for a FlatList embedded in a ScrollView.

So I faced the same problem while using a picker-based component inside <ScrollView> and the one thing that helped me solve the problem was adding
keyboardShouldPersistTaps={true} inside the <ScrollView> as a prop.
This is my code snippet.
<ScrollView keyboardShouldPersistTaps={true}>
<SelectionDD studentstatus={studentStatus}/>
<SearchableDD collegeNames={collegeNames} placeholder='University'/>
</ScrollView>

I have two Flatlist; each of them has many Item also has a feature to collapse and expand.
Because of that, I can't use SafeAreaView.
I saw another solution and found a new way.
I define one Flatlist in the core component ( without Scrollview) and render each Flatlist with a map function inside ListHeaderComponent and ListFooterComponent.
<View style={{flex: 1}}>
<FlatList
style={{backgroundColor: 'white'}}
refreshing={loading}
onRefresh={() => sample()}
ListHeaderComponent = {
<View>
{collapse/expandComponent}
{this.state.sample1&& content1.map((item, index) => this.renderList1(item,index))}
</View>
}
ListFooterComponent = {
<View>
{collapse/expandComponent}
{this.state.sample2 && content2.map((item, index) => this.renderlist2(item,index))}
</View>
}
/>
</View>

In my opinion i can use map instead of FlatList. But in my case i wan't to show large list. Not using FlatList may cause performance issue. so i used this to suppress warning https://github.com/GeekyAnts/NativeBase/issues/2947#issuecomment-549210509

Without hiding YellowBox you still can implement scroollable view inside scrollable view. You can use this library. It replace the default Scrollview from React Native.

This may help someone down the line, be sure you to check how your components are nested. Removing the ScrollView from the top component fixed the issue.
I ran into this issue because I had two components nested like this essentially:
Component 1
<ScrollView>
<OtherStuff />
<ListComponent />
</ScrollView>
My second component 'ListComponent' had a FlatList already wrapped with SafeAreaView.
<SafeAreaView style={styles.container}>
<FlatList
data={todoData}
renderItem={renderItem}
ItemSeparatorComponent={() => <View style={styles.separator} />}
keyExtractor={item => item.id.toString()}
/>
</SafeAreaView>
In the end I replaced the ScrollView from the first component with a View instead.

Use flatList like this ListHeaderComponent and ListFooterComponent:
<FlatList ListHeaderComponent={
<ScrollView
style={styles.yourstyle}
showsVerticalScrollIndicator={false}
>
<View style={styles.yourstyle}>
</View>
</ScrollView>
}
data={this.state.images}
renderItem={({ item, index }) => {
return (
<View
style={styles.yourstyle}
>
<Image
source={{
uri: item,
}}
style={styles.yourstyle}
resizeMode={"contain"}
/>
<Text
numberOfLines={2}
ellipsizeMode="tail"
style={styles.yourstyle}
>
{item.name}
</Text>
</View>
);
}}
keyExtractor={({ name }, index) => index.toString()}
ListFooterComponent={
<View style={styles.yourstyle}></View>
}
/>

If you use ScrollView and FlatList together you'll get inconsistent scroll behaviour.
So just remove ScrollView and use FlatList in a View.
<View flex={1}>
<FlatList
data={list}
renderItem={({ item }) => this.renderItem(item) }
keyExtractor={item => item.id}
/>
</View>

import React from 'react';
import { FlatList, ScrollViewProps } from 'react-native';
export const ScrollView: React.FC<ScrollViewProps> = props => {
return (
<FlatList
{...props}
data={[]}
renderItem={() => null}
ListHeaderComponent={() => (
<React.Fragment>{props.children}</React.Fragment>
)}
ListEmptyComponent={null}
keyExtractor={() => 'blank'}
/>
);
};
This will essentially work exactly like a ScrollView except without this error.

I was having this issue using a scrollview as parent view, and nesting a SelectBox from react-native-multi-selectbox package. I was able to solve this by adding listOptionProps={{nestedScrollEnabled: true}} like this:
<ScrollView>
<SelectBox
label="Select single"
options={serverData}
listOptionProps={{nestedScrollEnabled: true}}
value={input.elementSelected}
onChange={event =>
inputHandlerLang('elementSelected', event, key)
}
hideInputFilter={false}
/>
</ScrollView>
the error still present but scrolling within SelectBox works as well as within the parent scrollview. I also do have to suppress the error with LogBox. I don't know if there are any drawbacks to this but I'll try to test this more.
Update 1: this used to work in v0.68.2, but since I updated to patch v0.68.5, the warning became an error.

You have to remove ScrollView and enable scroll from FlatList using the property scrollEnabled={true}, you can place the other views inside ListHeaderComponent and ListFooterComponent
<View flex={1}>
<FlatList
data={data}
scrollEnabled={true}
showsVerticalScrollIndicator={false}
renderItem={({ item }) => (
<Text>{item.label}</Text>
)}
keyExtractor={item => item.id}
ListHeaderComponent={() => (
<Text>Title</Text>
)}
ListFooterComponent={() => (
<Text>Footer</Text>
)}
/>
</View>

Actually as I know, using nested VirtualizedLists, caused always performance issues, just the warning to that issue is new. I tried everything I found on the internet, non of them helped. I use now ScrollView or when you just have a normall View with maxHeight then you will be able to scroll if the content-height is bigger then the maxHeight of you View.
So:
<ScrollView>
{items.map((item, index) =>
<YourComponent key={index} item={item} />
)}
</ScrollView>
Or just:
<View style={{maxHeight: MAX_HEIGHT}}>
{items.map((item, index) =>
<YourComponent key={index} item={item} />
)}
</View>

This error disappeared because of using FlatList inside ScrollView. You can write like the following code.
<SafeAreaView style={styles.container}>
<View style={styles.container}>
<View>
<Header />
</View>
{(list.length == 0) &&
<View style={{flex:1, margin: 15}}>
<Text style={{textAlign: 'center'}}>No peripherals</Text>
</View>
}
<FlatList
data={list}
renderItem={({ item }) => this.renderItem(item) }
keyExtractor={item => item.id}
/>
</View>
</SafeAreaView>

You can add horizontal=True and contentContainerStyle={{ width: '100%' }} to the ScrollView parent.
<ScrollView
style={styles.collaborators}
contentContainerStyle={{ width: '100%' }} <--
horizontal <--
>
<FlatList
data={list?.slice(0, 10) || []}
keyExtractor={item => item.cc}
ItemSeparatorComponent={Separator}
renderItem={({ item }) => (
<Collaborator name={item.name} cc={item.cc} />
)}
/>
</ScrollView>

This worked for me (as a bit of a hack). Use a FlatList with empty data and null renderItem props instead of using a ScrollView
const emptyData = [];
const renderNullItem = () => null;
const App = () => {
const ListFooterComponent = (
<FlatList ... />
);
return (
<SafeAreaView>
<FlatList
data={emptyData}
renderItem={renderNullItem}
ListFooterComponent={ListFooterComponent}
/>
</SafeAreaView>
);
};

I had the same issue, and just got rid of it by removing the ScrollView around the FlatList. Because by default FlatList provides Scroll Functionality based on the length of content that it renders. 😊

How to use ReactNative FlatList ScrolltoIndex properly?

I'm a newbie in react native and I'm running into an issue I didn't manage to solve by myself.
So far this is how I am using it:
export default class Form extends React.Component {
state = {index: 0};
_keyExtractor = (item, index) => item.id;
myscrollToIndex = () => {
this.setState({index: ++this.state.index});
this.flatListRef.scrollToIndex({animated: true,index: this.state.index});
};
_renderItem = ({item}) => (
<View>
<Question {...item} />
<Button label='Next' onPress={this.myscrollToIndex} style={styles.buttonNext}/>
</View>
)
render() {
return (
<View style={styles.container}>
<FlatList
horizontal={false}
ref={(ref) => { this.flatListRef = ref; }}
scrollEnabled
data={this.props.form}
extraData={this.state}
keyExtractor={this._keyExtractor}
renderItem={this._renderItem} />
</View>
);
}
}
I would like to pass the index to myscrolltoindex function but I don't manage to as this.flatListRef gets ruled out when I do that.
Have anyone run into a similar issue ?
Thank you for your time

Use index param as well. And pass the index around.
For e.g _renderItem = ({item, index}) => ( <View> <Question {...item} /> <Button label='Next' onPress={this.myscrollToIndex(index) } style={styles.buttonNext}/> </View> )