React Native - FlatList Not Rendering - react-native

(Note: I'm using Expo for this app)
I'm attempting to render a FlatList that displays a list of printers. Here's the code:
<FlatList
data={printers}
keyExtractor={printer => printer.id}
renderItem={({ item }) => {
return (
<Printer
printerTitle={item.name}
selected={item.selected}
last={item === last(printers)}
/>
);
}}
/>
Here's the code for the <Printer /> component:
const Printer = props => {
const { last, printerTitle, selected } = props;
return (
<View style={[styles.container, last ? styles.lastContainer : null]}>
<View style={styles.innerContainer}>
<View style={styles.leftContainter}>
{selected ? (
<Image source={selected ? Images.checkedCircle : null} />
) : null}
</View>
<View style={styles.printerDetails}>
<Text style={styles.printerTitle}>{printerTitle}</Text>
</View>
</View>
</View>
);
};
...
export default Printer;
I can't seem to get the <Printer /> component to render. I have tried including a similar custom component (that has worked in a FlatList in another part of the app) in the renderItem prop, and it doesn't work either.
However, when I replace the <Printer /> component with <Text>{item.name}</Text> component, the printer name renders like I would expect it to.
Has anyone run into this issue before, or does anyone have a solution?

In my case, where I'm rendering a custom component for each item in the list, it wasn't rendering because I accidentally had {} surrounding the return part of the renderItem prop instead of ().
Changing:
<FlatList
data={array}
renderItem={({item, index}) => { <CustomItemComponent /> }}
/>
to this:
<FlatList
data={array}
renderItem={({item, index}) => ( <CustomItemComponent /> )}
/>
Solved my issues.

I suspect there are two issues at hand: one is that your FlatList is not filling the screen (namely its parent view) and the other is that your Printer component is not being sized correctly.
For the first issue, put a style with { flex: 1 } on your FlatList. This way it will fill its parent view.
For the second issue, try adding { borderColor: 'red', borderWidth: 1 } to your Printer components, just so that you can more easily see where they're being rendered. If they seem like they have no width, make sure you haven't overridden alignSelf on the Printer component's root view. If they seem like they have no height, add height: 100 temporarily just so you can see what the contents of the Printer components look like.
Within your Printer component, make sure to specify the width and height of your image on the Image component like { width: 40, height: 30 } or whatever the dimensions of your image is in logical pixels.

I have same problem.
Resolve with adding width to FlatList
render() {
const dimensions = Dimensions.get('window');
const screenWidth = dimensions.width;
return(
<FlatList
style={{
flex: 1,
width: screenWidth,
}}
... some code here
/>
)
}

You can't use the keyExtractor in this way, make this function like below. It might solve your problem.
_keyExtractor = (item, index) => index;
If you update your question with you printer component code we can help you better.

In my case I accidentally made it a pair tag: <FlatList></FlatList>, which for some reason breaks rendering of list items.

in my case Container was not having width of 100%:
const Container = styled.View`
border: 1px solid #ececec;
margin-top: 43px;
padding-top: 36px
padding-bottom: 112px;
width: 100%;
`;
const StyledFlatList = styled(
FlatList as new () => FlatList<SimilarRewards_viewer['merchants']['edges'][0]>
)`
width: 100%;
height: 150px;
flex: 1;
padding-left: 15px;
padding-right: 15px;
`;

Related

Last Image is being cropped, when using ScrollView in react-native

I am trying to build something like instagram posts, that is continuous images that can be scrolled. But the last image is being cropped, that is only the upper half of it is being visible, there are several posts, regarding the same, but those didnt help, (contentContainerStyle={{flexGrow: 1,}}, adding height to a invisible view). Can someone please point out what is going wrong?
EDIT: I have changed scrollview to flatlist and still face the same problem, can you suggest what else to do?
EDIT 2: realised that the <Header /> and <Stories /> above the flatlist are not letting it scroll completely, that is the height that
it is not scrolling is proportional to height of <Header /> and <Stories />
post.js
const Post = ({post}) => {
return (
<View style={{flex:1}}>
<Divider width = {0.5}/>
<PostHeader post={post}/>
<PostImage post={post} />
<PostFooter post={post}/>
</View>
)
}
const PostImage = ({post}) => {
return (
<View style={styles.postContainer}>
<Image style={styles.image} source={{uri: post.post_url}}></Image>
</View>
)
}
const styles = StyleSheet.create({
container: {
},
dp: {
width: 35,
height: 35,
margin:5,
borderRadius: 20,
borderWidth : 1,
borderColor : '#ff8501'
},
postContainer: {
width: '100%',
height: 400,
},
image: {
height: '100%',
resizeMode: 'cover',
}
})
homescreen.js
const HomeScreen = () => {
return (
<SafeAreaView >
<Header />
<Stories />
{/* <ScrollView>
{
POSTS.map((post, index) => {
return (
<Post key={index} post={post} />
)
})
}
</ScrollView> */}
<FlatList data={POSTS} renderItem={({item}) => <Post post={item} />} />
</SafeAreaView>
)
}
If you want to render repetitive view so why you are not using Faltlist instead of Scrollview. For repetitive view react native provide one component which is called Flatlist and pass you array data in render item it will give you better performance as well.
<SafeAreaView style={styles.container}>
<FlatList
data={DATA}
renderItem={renderItem}
keyExtractor={item => item.id}
/>
</SafeAreaView>
const renderItem = ({ item }) => (
<Divider width = {0.5}/>
<PostHeader post={item}/>
<PostImage post={item} />
</View>
);
const styles = StyleSheet.create({
container: {
flex: 1,
},
item: {
backgroundColor: '#f9c2ff',
padding: 20,
marginVertical: 8,
marginHorizontal: 16,
},
});
According to React Native docs FlatList is the Component you should use:
ScrollView renders all its react child components at once, but this has a performance downside.
Imagine you have a very long list of items you want to display, maybe several screens worth of content. Creating JS components and native views for everything all at once, much of which may not even be shown, will contribute to slow rendering and increased memory usage.
This is where FlatList comes into play. FlatList renders items lazily, when they are about to appear, and removes items that scroll way off screen to save memory and processing time.
FlatList is also handy if you want to render separators between your items, multiple columns, infinite scroll loading, or any number of other features it supports out of the box.
const Post = () => {
renderItemHandler = ({post, index}) => (
<View key={index} >
<Divider width={0.5}/>
<PostHeader post={post}/>
<PostImage post={post} />
</View>
)
return (
<SafeAreaView style={{flex: 1}}>
<View style={{height: "90%"}}>
<Flatlist
data={POSTS}
renderItem={renderItemHandler}
keyExtractor={item => item.id}
/>
</View>
</SafeAreaView>
)
}

Component only reachable by scrolling regardless of window size

I'm trying to make a layout so that the later parts of the view are only reachable by scrolling.
Currently I'm using Dimensions to generate Views with the correct height. Is there a better way of doing so? My current solution doesn't seem too correct.
export default function MyApp() {
const height = Dimensions.get('window').height;
return (
<View style={styles.container}>
<ScrollView>
<View style={{backgroundColor: 'green', height:height}}/>
<View style={{backgroundColor: 'red', height:40}}/>
</ScrollView>
</View>
);
}
const styles = StyleSheet.create({
container:{
backgroundColor: 'white',
flex: 1
}
});
You can use VirtualizedList component, for example as
<VirtualizedList
data={['body']}
renderItem={({ item }) => (
<View style={styles.screen}>
{/* Put more content for body */}
</View>
)}
keyExtractor={(item, index) => index.toString()}
getItemCount={() => {
return 1;
}}
getItem={(data, index) => {
return data[index];
}}>
</VirtualizedList>
Your solution work, but not good and it have downside, when you change your phone orientation to landscape there will be bug. I dont like using Dimensions in my code unless there is no other way or use Dimensions addEventListener to listen window size and update component whenever window size change. I will suggest you a better way.
First, create a component called LayoutSizeAwareView, after this view rendered, we will catch it size from onLayout props and use them to render it children.
const LayoutSizeAwareView = (props) => {
const [size, setSize] = React.useState({width: 0, height: 0});
return (
<View
...props,
onLayout={(e) => {
setSize({
width: e.nativeEvent.layout.width,
height: e.nativeEvent.layout.height,
})
props.onLayout(e)
}}
>
{props.children(size)}
</View>
)
}
And then, in your case, use it like this
export default function MyApp() {
return (
<LayoutSizeAwareView style={styles.container}>
{({width, height}) => {
return (
<ScrollView>
<View style={{backgroundColor: 'green', height: height}}/>
<View style={{backgroundColor: 'red', height: 40}}/>
</ScrollView>
)
}}
</View>
);
}
const styles = StyleSheet.create({
container:{
backgroundColor: 'white',
flex: 1
}
});
This way your code look even cooler, there will be some typo in my code since I dont have IDE here, but you might get the idea.

Cascade text color with Styled Components on React Native

I'm trying to create a component with React Native that includes a <Text> component inside the wrapped component:
const MyComponent = props => (
<View {...props}>
<Text {...props}>Hello world</Text>
<View>
)
const MyRedComponent = styled(MyComponent)`
color: #000;
margin-left: 10px;
background: #F00;
`
I'm composing my component this way so I could change the the text color from the same styled component as I'm changing the background color:
const MyBlueComponent = styled(MyRedComponent)`
color: #FFF;
background: #00F;
`
However with this approach there is a problem that all of the styles get applied to the <Text> component, not only the color; in this example the <Text> component also gets the margin-left style from the parent styles which is not preferred. I'd only like the text color to be cascaded to the <Text> component.
Is this possible using Styled Components with React Native?
You can create a wrapper function using StyleSheet.flatten and pick the color from the resulting object:
const MyComponent = props => (
<View {...props}>
<Text style={{ color: StyleSheet.flatten(props.styles).color }}>Hello world</Text>
<View>
)
const MyRedComponent = styled(MyComponent)`
color: #000;
margin-left: 10px;
background: #F00;
`
It makes sense to extract the picking to its own function. For example you could create the following wrapper:
const pickColorFromStyles = styles => {
const { color } = StyleSheet.flatten(styles)
return { color }
}
...and use that function in your component:
const MyComponent = props => (
<View {...props}>
<Text style={pickColorFromStyles(props.styles)}>Hello world</Text>
<View>
)
Notice the warning with using StyleSheet.flatten from the documentation page:
NOTE: Exercise caution as abusing this can tax you in terms of optimizations. IDs enable optimizations through the bridge and memory in general. Refering to style objects directly will deprive you of these optimizations.

Separator style for header and body in FlatList

Currently, I'm having a problem with FlatList.
I have a component to render a list book.
By design, the header's width is the width of the screen and the body will be padding left and right 10px.
So I used contentContainerStyle={{paddingHorizontal: 10}}.
But The result is that the header and body are 10px padding left and right.
Please suggest a way to resolve it. Sorry for my bad English!!
Update: I'm so sorry for not describing my problem thoroughly.
In main.tsx
...
public render() {
return (
<FlatList
key...
data={..}
renderItem={this.renderItems}
ListHeaderComponent={this.renderHeader}
contentContainerStyle={styles.contentStyle}
/>
);
}
private renderHeader = () => {
return (
<View style={style.header}
//TODO something ...
</View>
);
}
private renderItems: ListRenderItem<IBook> = ({ item: {bookId} }) => bookId ?
(
<BookGridCell
title={...}
image={...}
//TODO more..
/>
) : <View style={styles.emptyBox} />
}
At renderItems, I called a component BookGridCell. In this component, the design of a book is set up. So if I directly add style inside renderItems, each book will have a left and right margin of 10px, not the entire body.
When use contentContainerStyle
with contenContainerStyle
When directly add style inside renderItems
with not use contentContainerStyle
Give a style to your body.
style={styles.bodyContainer}
and then inside StyleSheet add property.
const styles = StyleSheet.create({
bodyContainer: {
paddingHorizontal: 10
},
This is the correct way or
you can directly add padding inside your View.
style={{ paddingHorizontal: 10 }}

React Native FlatList last item visibility issue

I am fetching products list and then displaying using a FlatList, my list contains 5 items and as you can see FlatList row height is variable because of varying description text. So the issue is my last item card is not completely visible maybe this is some kind of flat list issue or layout issue. Any help would be highly appreciated
renderProducts() {
if (this.props.loading === true) {
return (
<View style={Styles.spinnerStyle}>
<ActivityIndicator size='large' />
</View>
);
}
return (
<FlatList
data={this.props.myProducts}
keyExtractor={(item) => item.id}
renderItem={({ item }) => (
<Card
title={item.title}
image={{
uri: item.image !== null ? item.image.src :'../resImage.jpg'
}}
>
<Text style={{ marginBottom: 10 }}>
{item.body_html}
</Text>
<Button
icon={{ name: 'code' }}
backgroundColor='#03A9F4'
fontFamily='Lato'
buttonStyle={{ borderRadius: 0, marginLeft: 0, marginRight: 0, marginBottom: 0 }}
title='VIEW NOW'
/>
</Card>
)}
/>
);
}
render() {
return (
<View>
<View style={Styles.viewStyle}>
<Text style {Styles.textStyle}>ProductsList</Text>
</View>
{
this.renderProducts()
}
</View>
);
}
Set bottom padding to the <FlatList> content container:
<FlatList
contentContainerStyle={{ paddingBottom: 20 }}
/>
Add {flex: 1} to the View tag housing the Flatlist component.
In my case,
const App = () => {
return (
<Provider store={createStore(reducers)}>
<View style={{ flex: 1 }}>
<Header headerText={'My App'} />
<ScreenTabs /> // this is my content with FlatList
</View>
</Provider>
);
};
export default App;
Just wrap it in a view with flex:1
<ParentView style={{flex:1}
<View style={{flex:1}}>
// Your flatlist
<View>
</ParentView>
Also, note that the each parent of this "View" in which Flatlist is wrapped must also be a View with Flex of 1. Otherwise, that your flatlist wont be visible.
use contentContainerStyle props of FlatList
<FlatList contentContainerStyle={{ paddingBottom: 20}} />
Latest update:
react-navigation has a SafeAreaView with an option to not show that bottom area.
import { SafeAreaView } from 'react-navigation';
<SafeAreaView forceInset={{ bottom: 'never' }} />
Old response below:
You can't see your list with flex: 1 because flex: 1 will grow the component to the parent. If the parent doesn't have flex: 1, it won't stretch to its parent or the screen. Keep in mind, however, that flex: 1 with a SafeAreaView will cause the bottom safe area to show. This will look bad if your SafeAreaView backgroundColor is a different color from your list's back ground.
My old workaround was to add an item to the bottom of the array of items, but I'm still exploring how to scroll past/under the bottom safe area margin with a FlatList (which is how I found this post to begin with).
Update: Using ListFooterComponent you can create even a plain white "footer" with height and/or a margin
For example (I wouldn't directly copy and paste this if I were you... there's surely a better way to detect bezel-less iPhones, especially in 2019 when we have more than one)
ListFooterComponent={<View style={{ height: 0, marginBottom: 90 }}></View>}
This is how I would do it, using the iPhoneX's height for now. But it's not future-proof since the conditional will need to be updated every time a new iPhone with no bezels comes out:
ListFooterComponent={<View style={{ height: 0, marginBottom: noBezels ? 90 : 0 }}></View>}
Or you could just always have some spacing at the bottom, like a loading gif, a message... whatever.
UPDATE 2:
I found out about react-native-device-info which has a hasNotch() method. I find that useful for styling for iPhones with no bezels by combining hasNotch() with Platform.OS === 'ios'
You can try this solution
For Vertical FlatList:
<FlatList
ListFooterComponent={<View />}
ListFooterComponentStyle={{height:200}}
/>
For Horizontal FlatList:
<FlatList
contentContainerStyle={{paddingRight:40}}
/>
For IOS issues you can apply some IOS specific props:
<FlatList
// ...
contentInset={{top: 0, bottom: 20, left: 0, right: 0}}
contentInsetAdjustmentBehavior="automatic"
// ...
/>
The solution with contentContainerStyle padding didn't seem the best overall for fixing the safe area IOS issues in my case.
Work very well for me
<FlatList
data={data}
contentContainerStyle={{ paddingBottom: 30 }}
style={{height: '95%'}}
renderItem={({ item, index }) => (
<ListItem item={item} onPress={() => handlePress(item, index)} />
)}
/>
Make use of the contentContainerStyle prop in the flatlist
<FlatList contentContainerStyle={{paddingBottom: 10}} />
For dynamic flatlist, you can assign height to the parent view. I resolved it with same.
<View style={{height:'80%'}}>
<Flatlist
extraData={data}
data={data}
renderItem={renderItem}
/>
</View>
I had the same issue and found the solution. To fix the issue just add style={{flex: 1}} for each View element who is a parent for FlatList.
See updated code below.
render() {
return (
<View style={{flex: 1}}> // Here you should add style as {flex: 1}
<View style={Styles.viewStyle}>
<Text style={Styles.textStyle}>ProductsList</Text>
</View>
{ this.renderProducts() }
</View>
);
}
This worked for me.
<View style={{flex: 1}}>
<FlatList
style={{flex: 1}}
data={data}
renderItem={({item}) => (
<ListItem item={item} onPress={() => handlePress(item)} />
)}
/>
</View>
#krish solution is great for the fixed-size list items, however as
#Neeraj Sewani said, it may not be suitable for dynamic size list items.
so you can fix the issue like this -in case direction is column -:
<View style={{height: '90%'}}>
<FlatList/>
</View>
Otherwise, -in case direction is row -:
<View style={{height: '90%', width:'90%'}}>
<FlatList/>
</View>
I was seeing this same problem in our Android + iOS React Native hybrid app. We embed the FlatList component within our native UIs inside a Fragment in Android and we were unable to scroll to the last item in the list, even though the scroll indicator would show that there was more to scroll, the ScrollView would simply not scroll further. I tried all the combinations of using a wrapping <View style={{flex:1}}> to wrap the FlatList as well as using contentContainerStyle={{flexGrow:1}} on the FlatList without success. Pursuing the clue further it turned out that the FlatList needs an absolute, predefined height on Android to allow scroll to the bottom - it works just fine on iOS but on Android using match_parent wasn't going to work. Since we need to support all types of devices, phone and tablet too, it wasn't possible to pre-define an absolute height either.
To fix this, I made a custom FrameLayout subclass to house the ReactRootView's fragment, which overrides onLayout() to ignore the child view measurements, forcing the views to have the exact dimensions of the FrameLayout, somewhat like so in Kotlin:
class StretchFrameLayout #JvmOverloads constructor(
context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : FrameLayout(context, attrs, defStyleAttr) {
override fun onLayout(changed: Boolean, left: Int, top: Int, right: Int, bottom: Int) {
for (child in children){
if (child.visibility == View.GONE) continue
child.updateLayoutParams {
this.width = measuredWidth
this.height = measuredHeight
}
if (needsRelayout){
handler.postDelayed({child.requestLayout()},1)
}
}
super.onLayout(changed, left, top, right, bottom)
}
}
This work very well in my case:
<FlatList
data={todos}
contentContainerStyle={{ height: '100%' }}
renderItem={({ item }) => <Todos items={item} pressed={pressed} />}
/>
I've solved it doing contentInset={{ bottom: data.length * itemStyle.height, }} with itemStyle.height being 50 worked fine.