admin管理员组文章数量:1320402
I am learning react native by myself and trying to develop an application.
What I understand is that whenever a component is re-rendered, all its children are re-rendered.
To simplify, Here are a few of my components in simplified way :
BorderedButton :
export default function BorderedButton({ title, onPress, textStyle, style, inProgress }) {
return (
<View style={[styles.container, style]}>
<Pressable
onPress={onPress}
disabled={inProgress}>
{!inProgress && <AppText style={[styles.text, textStyle]}>{title}</AppText>}
{
inProgress && <ActivityIndicator
animating={true}
color='white'
/>
}
</Pressable>
</View >
);
}
Feed Screen :
export default function FeedScreen() {
var accessToken = useSelector(state => state.authState.accessToken);
const isLoggedIn = useSelector(state => state.authState.isLoggedIn);
const userlatitude = useSelector(state => state.locationState.latitude);
const userLongitude = useSelector(state => state.locationState.longitude);
const isFocused = useIsFocused();
const navigation = useNavigation();
const [latitude, setLatitude] = useState(userlatitude);
const [longitude, setLongitude] = useState(userLongitude);
const [isHardRefreshPending, setIsHardRefreshPending] = useState(false);
console.log("DEBUGGGGG loading Feedscreen !");
if (!isLoggedIn) {
accessToken = undefined;
}
const intervalRef = useRef(null);
const [activities, setActivities] = useState([]);
const [loading, setLoading] = useState(false);
const [getData] = useLazyQuery(load_feed);
useEffect(() => {
if (intervalRef.current) {
clearInterval(intervalRef.current);
intervalRef.current = null;
}
continuationTokenRef.current = null;
setActivities([]);
refreshFeed(true);
}, [isLoggedIn, latitude, longitude]);
useEffect(() => {
if (activities === undefined
|| activities.length === 0) {
if (!intervalRef.current && !loading) {
const intervalId = setInterval(refreshFeed.bind(this, true), 5000);
intervalRef.current = intervalId;
}
} else {
if (intervalRef.current) {
clearInterval(intervalRef.current);
intervalRef.current = null;
}
}
}, [activities]);
useEffect(() => {
if (isHardRefreshPending) {
setIsHardRefreshPending(false);
refreshFeed(true);
}
}, [loading]);
function parseAndUpdateData(data, isHardRefresh) {
//logic to load/parse data and set activities state
//......
//... setActivities
}
function refreshFeed(isHardRefresh) {
setLoading(true);
getData({
context: {
headers: {
"Authorization": isLoggedIn ? `Bearer ${accessToken}` : ""
}
},
variables: {
latitude,
longitude,
size: defaultFeedSizeToFetch,
continuationToken: isHardRefresh ? null : continuationTokenRef.current
},
onCompleted: (data) => {
setLoading(false);
parseAndUpdateData(data, isHardRefresh);
},
onError: ({ graphQLErrors, networkError }) => {
if (graphQLErrors) {
graphQLErrors.map((message) => {
const errorJson = JSON.stringify(message);
isFocused && Alert.alert('Error', `Some issue getting the feed, please try again later`, [
{
text: 'Ok',
style: 'default'
}],
{
cancelable: false,
userInterfaceStyle: 'light'
}
);
})
}
if (networkError) {
isFocused && alert('please check your connection : ' + networkError.message);
}
setLoading(false);
}
})
}
function renderFeedCard(itemData) {
return (
<FeedCard activityData={itemData.item} />
);
}
const generateCustomUUID = () => {
return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
var r = Math.random() * 16 | 0, v = c === 'x' ? r : (r & 0x3 | 0x8);
return v.toString(16);
});
};
function getActivitiesOrPlaceHolderMessage() {
if (loading
&& (activities === undefined || activities.length === 0))
return (
<AppText>getting your feed ...</AppText>
);
if (activities && activities.length > 0)
return (
<View style={styles.activityContainer}>
<FlatList
keyExtractor={item => generateCustomUUID()}
data={activities}
renderItem={renderFeedCard}
contentContainerStyle={{
paddingBottom: 20
}}
onEndReached={refreshFeed.bind(this, false)}
style={{ zIndex: -1, flex: 1 }}
refreshing={true}
refreshControl={
<RefreshControl
refreshing={loading}
onRefresh={refreshFeed.bind(this, true)}
title="getting latest feed for you "
tintColor="#fff"
titleColor="#fff"
/>
}
/>
</View>
)
else
return (
<View>
<AppText>Oops ! seems like no activities happening around you. But you can try searching for activities around some other location by searching the location </AppText>
<BorderedButton
style={{
marginVertical: 20
}}
onPress={() => {
navigation.navigate("AddActivity");
}}
title={"Plan something now !"}
textStyle={{
fontFamily: "InterRegular"
}} />
</View>
);
}
return (
<PageContainer>
<View style={[styles.rootContainer, { display: backdropDisplay }]}>
<View style={styles.textContainer}>
<AppText style={styles.headingText}>Here are some amazing plans happening around you.</AppText>
</View>
<View style={styles.textContainer}>
<AppText style={styles.subHeadingText}>exciting new plans for you !</AppText>
</View>
{getActivitiesOrPlaceHolderMessage()}
</View>
</PageContainer>
);
}
FeedCard :
export default function FeedCard({ activityData }) {
console.log("Rendering Feed card for activity : ", activityData);
const isLoggedIn = useSelector(state => state.authState.isLoggedIn);
const [activity, setActivity] = useState({ ...activityData });
const [isApiInProgress, setIsApiInProgress] = useState(false);
const accessToken = useSelector(state => state.authState.accessToken);
const [triggerJoinActivityMutation] = useMutation(request_activity_joining, {
context: {
headers: {
"Authorization": `Bearer ${accessToken}`
}
},
variables: {
activityId: activity.activityId
},
onError: ({ graphQLErrors, networkError }) => {
console.log("DEBUGGGGG ERROR BLOCK");
setIsApiInProgress(false);
if (graphQLErrors) {
graphQLErrors.map((message, location, path) => {
const errorJson = JSON.stringify(message);
const errorObj = JSON.parse(errorJson);
Alert.alert('Error', `${errorObj.message}`, [
{
text: 'Ok',
style: 'default'
}],
{
cancelable: false,
userInterfaceStyle: 'light'
}
);
})
}
if (networkError) {
alert('please check your connection');
}
},
onCompleted: (response) => {
const status = response.requestActivityJoining.activityRequestStatus;
console.log("DEBUGGG status :", status);
setIsApiInProgress(false);
setActivity((prev) => {
const newActivity = { ...prev };
newActivity.requestStatus = status;
return newActivity;
})
}
});
const [triggerOptOutMutation] = useMutation(request_activity_opt_out, {
context: {
headers: {
"Authorization": `Bearer ${accessToken}`
}
},
variables: {
activityId: activity.activityId,
state: Math.random(),
},
onError: ({ graphQLErrors, networkError }) => {
setIsApiInProgress(false);
console.log("DEBUGGGG ERROR");
if (graphQLErrors) {
graphQLErrors.map((message, location, path) => {
const errorJson = JSON.stringify(message);
const errorObj = JSON.parse(errorJson);
Alert.alert('Error', `${errorObj.message}`, [
{
text: 'Ok',
style: 'default'
}],
{
cancelable: false,
userInterfaceStyle: 'light'
}
);
})
}
if (networkError) {
alert('please check your connection');
}
},
onCompleted: (response) => {
const status = response.requestActivityOptOut.activityRequestStatus;
console.log('request status in opt out api response', status);
setIsApiInProgress(false);
setActivity((prev) => {
const newActivity = { ...prev };
newActivity.requestStatus = status;
return newActivity;
})
}
});
function initiateActivityJoiningRequest() {
console.log("trigger join mutation");
if (!isLoggedIn) {
Alert.alert("Please log in to participate in this activity ");
return;
}
setIsApiInProgress(true);
console.log("trigger join mutation ------ 2");
triggerJoinActivityMutation();
}
function initiateActivityOptOut() {
console.log("trigger opt out mutation");
setIsApiInProgress(true);
console.log("trigger opt out mutation ----- 2");
triggerOptOutMutation();
}
function getButtonComponent() {
const activityRequestStatus = activity.requestStatus;
if (activityRequestStatus && activityRequestStatus == 'PENDING_HOST_APPROVAL'
|| activityRequestStatus && activityRequestStatus == 'HOST_APPROVED') {
return (
<BorderedButton
onPress={initiateActivityOptOut}
inProgress={isApiInProgress}
title={'Opt out'}
/>
);
}
return (
<BorderedButton
title={'Request'}
onPress={initiateActivityJoiningRequest}
inProgress={isApiInProgress} />
);
}
return (
<View style={[styles.rootContainer]} >
<View style={styles.userAndCompanyInfoContainer}>
<UserInfo
relativeSize={userInfoRelativeSize}
userInfo={{
userId: activity.hostId,
displayName: activity.hostDisplayName,
profileImageUrl: activity.profileImageUrl
}}
/>
<CompanyInfo
relativeSize={userInfoRelativeSize}
Name={activity.hostOrgName} />
</View>
<View style={styles.titleContainer}>
<FeedCardTitle>{activity.title}</FeedCardTitle>
</View>
<View style={styles.descriptionContainer}>
<AppText style={styles.descriptionText}>{activity.description}</AppText>
</View>
<View style={styles.locationContainer}>
<LocationCard locationDescription={activity.locationDescription} />
</View>
<View style={styles.dateAndTimeContainer}>
<FeedCardDate dateDay={activity.dateDay} dateMonth={activity.dateMonth} />
<TimeInfo time={activity.tentativeTime} />
</View>
<View style={styles.buttonContainer}>
<ParticipantsSnapshot
participantsImages={[...activityData.participantsImages]} />
{getButtonComponent()}
</View>
</View >
);
}
The behaviour I am unable to relate with is - When a button in pressed in the FeedCard, it calls the method triggerJoinActivityMutation or triggerOptOutMutation. I am setting the state isApiInProgress to true, which is used by the button component to show the loading animation. But whenever setIsApiInProgress is called in any of these 2 methods, it also re-renders the FeedScreen. Ideally the state change only moves downwards (what I have learned) then why does the feed screen reloads ?
I know this because the moment I comment all setIsApiInPogress method calls, things start working the way as expected, the FeedScreen never re-renders
My understanding is as follows - Feedscreen renders a list of FeedCards -> which in turn uses BorderedButton. Bordered button uses a state(isApiInProgress) which belongs to FeedCard. So when the state(isApiInProgress is updated) it should re-render the FeedCard and BorderedButton and not the FeedScreen.
Can anyone help me understand this behaviour. I tried exploring the web but could not understand the root cause of this behaviour.
I am learning react native by myself and trying to develop an application.
What I understand is that whenever a component is re-rendered, all its children are re-rendered.
To simplify, Here are a few of my components in simplified way :
BorderedButton :
export default function BorderedButton({ title, onPress, textStyle, style, inProgress }) {
return (
<View style={[styles.container, style]}>
<Pressable
onPress={onPress}
disabled={inProgress}>
{!inProgress && <AppText style={[styles.text, textStyle]}>{title}</AppText>}
{
inProgress && <ActivityIndicator
animating={true}
color='white'
/>
}
</Pressable>
</View >
);
}
Feed Screen :
export default function FeedScreen() {
var accessToken = useSelector(state => state.authState.accessToken);
const isLoggedIn = useSelector(state => state.authState.isLoggedIn);
const userlatitude = useSelector(state => state.locationState.latitude);
const userLongitude = useSelector(state => state.locationState.longitude);
const isFocused = useIsFocused();
const navigation = useNavigation();
const [latitude, setLatitude] = useState(userlatitude);
const [longitude, setLongitude] = useState(userLongitude);
const [isHardRefreshPending, setIsHardRefreshPending] = useState(false);
console.log("DEBUGGGGG loading Feedscreen !");
if (!isLoggedIn) {
accessToken = undefined;
}
const intervalRef = useRef(null);
const [activities, setActivities] = useState([]);
const [loading, setLoading] = useState(false);
const [getData] = useLazyQuery(load_feed);
useEffect(() => {
if (intervalRef.current) {
clearInterval(intervalRef.current);
intervalRef.current = null;
}
continuationTokenRef.current = null;
setActivities([]);
refreshFeed(true);
}, [isLoggedIn, latitude, longitude]);
useEffect(() => {
if (activities === undefined
|| activities.length === 0) {
if (!intervalRef.current && !loading) {
const intervalId = setInterval(refreshFeed.bind(this, true), 5000);
intervalRef.current = intervalId;
}
} else {
if (intervalRef.current) {
clearInterval(intervalRef.current);
intervalRef.current = null;
}
}
}, [activities]);
useEffect(() => {
if (isHardRefreshPending) {
setIsHardRefreshPending(false);
refreshFeed(true);
}
}, [loading]);
function parseAndUpdateData(data, isHardRefresh) {
//logic to load/parse data and set activities state
//......
//... setActivities
}
function refreshFeed(isHardRefresh) {
setLoading(true);
getData({
context: {
headers: {
"Authorization": isLoggedIn ? `Bearer ${accessToken}` : ""
}
},
variables: {
latitude,
longitude,
size: defaultFeedSizeToFetch,
continuationToken: isHardRefresh ? null : continuationTokenRef.current
},
onCompleted: (data) => {
setLoading(false);
parseAndUpdateData(data, isHardRefresh);
},
onError: ({ graphQLErrors, networkError }) => {
if (graphQLErrors) {
graphQLErrors.map((message) => {
const errorJson = JSON.stringify(message);
isFocused && Alert.alert('Error', `Some issue getting the feed, please try again later`, [
{
text: 'Ok',
style: 'default'
}],
{
cancelable: false,
userInterfaceStyle: 'light'
}
);
})
}
if (networkError) {
isFocused && alert('please check your connection : ' + networkError.message);
}
setLoading(false);
}
})
}
function renderFeedCard(itemData) {
return (
<FeedCard activityData={itemData.item} />
);
}
const generateCustomUUID = () => {
return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
var r = Math.random() * 16 | 0, v = c === 'x' ? r : (r & 0x3 | 0x8);
return v.toString(16);
});
};
function getActivitiesOrPlaceHolderMessage() {
if (loading
&& (activities === undefined || activities.length === 0))
return (
<AppText>getting your feed ...</AppText>
);
if (activities && activities.length > 0)
return (
<View style={styles.activityContainer}>
<FlatList
keyExtractor={item => generateCustomUUID()}
data={activities}
renderItem={renderFeedCard}
contentContainerStyle={{
paddingBottom: 20
}}
onEndReached={refreshFeed.bind(this, false)}
style={{ zIndex: -1, flex: 1 }}
refreshing={true}
refreshControl={
<RefreshControl
refreshing={loading}
onRefresh={refreshFeed.bind(this, true)}
title="getting latest feed for you "
tintColor="#fff"
titleColor="#fff"
/>
}
/>
</View>
)
else
return (
<View>
<AppText>Oops ! seems like no activities happening around you. But you can try searching for activities around some other location by searching the location </AppText>
<BorderedButton
style={{
marginVertical: 20
}}
onPress={() => {
navigation.navigate("AddActivity");
}}
title={"Plan something now !"}
textStyle={{
fontFamily: "InterRegular"
}} />
</View>
);
}
return (
<PageContainer>
<View style={[styles.rootContainer, { display: backdropDisplay }]}>
<View style={styles.textContainer}>
<AppText style={styles.headingText}>Here are some amazing plans happening around you.</AppText>
</View>
<View style={styles.textContainer}>
<AppText style={styles.subHeadingText}>exciting new plans for you !</AppText>
</View>
{getActivitiesOrPlaceHolderMessage()}
</View>
</PageContainer>
);
}
FeedCard :
export default function FeedCard({ activityData }) {
console.log("Rendering Feed card for activity : ", activityData);
const isLoggedIn = useSelector(state => state.authState.isLoggedIn);
const [activity, setActivity] = useState({ ...activityData });
const [isApiInProgress, setIsApiInProgress] = useState(false);
const accessToken = useSelector(state => state.authState.accessToken);
const [triggerJoinActivityMutation] = useMutation(request_activity_joining, {
context: {
headers: {
"Authorization": `Bearer ${accessToken}`
}
},
variables: {
activityId: activity.activityId
},
onError: ({ graphQLErrors, networkError }) => {
console.log("DEBUGGGGG ERROR BLOCK");
setIsApiInProgress(false);
if (graphQLErrors) {
graphQLErrors.map((message, location, path) => {
const errorJson = JSON.stringify(message);
const errorObj = JSON.parse(errorJson);
Alert.alert('Error', `${errorObj.message}`, [
{
text: 'Ok',
style: 'default'
}],
{
cancelable: false,
userInterfaceStyle: 'light'
}
);
})
}
if (networkError) {
alert('please check your connection');
}
},
onCompleted: (response) => {
const status = response.requestActivityJoining.activityRequestStatus;
console.log("DEBUGGG status :", status);
setIsApiInProgress(false);
setActivity((prev) => {
const newActivity = { ...prev };
newActivity.requestStatus = status;
return newActivity;
})
}
});
const [triggerOptOutMutation] = useMutation(request_activity_opt_out, {
context: {
headers: {
"Authorization": `Bearer ${accessToken}`
}
},
variables: {
activityId: activity.activityId,
state: Math.random(),
},
onError: ({ graphQLErrors, networkError }) => {
setIsApiInProgress(false);
console.log("DEBUGGGG ERROR");
if (graphQLErrors) {
graphQLErrors.map((message, location, path) => {
const errorJson = JSON.stringify(message);
const errorObj = JSON.parse(errorJson);
Alert.alert('Error', `${errorObj.message}`, [
{
text: 'Ok',
style: 'default'
}],
{
cancelable: false,
userInterfaceStyle: 'light'
}
);
})
}
if (networkError) {
alert('please check your connection');
}
},
onCompleted: (response) => {
const status = response.requestActivityOptOut.activityRequestStatus;
console.log('request status in opt out api response', status);
setIsApiInProgress(false);
setActivity((prev) => {
const newActivity = { ...prev };
newActivity.requestStatus = status;
return newActivity;
})
}
});
function initiateActivityJoiningRequest() {
console.log("trigger join mutation");
if (!isLoggedIn) {
Alert.alert("Please log in to participate in this activity ");
return;
}
setIsApiInProgress(true);
console.log("trigger join mutation ------ 2");
triggerJoinActivityMutation();
}
function initiateActivityOptOut() {
console.log("trigger opt out mutation");
setIsApiInProgress(true);
console.log("trigger opt out mutation ----- 2");
triggerOptOutMutation();
}
function getButtonComponent() {
const activityRequestStatus = activity.requestStatus;
if (activityRequestStatus && activityRequestStatus == 'PENDING_HOST_APPROVAL'
|| activityRequestStatus && activityRequestStatus == 'HOST_APPROVED') {
return (
<BorderedButton
onPress={initiateActivityOptOut}
inProgress={isApiInProgress}
title={'Opt out'}
/>
);
}
return (
<BorderedButton
title={'Request'}
onPress={initiateActivityJoiningRequest}
inProgress={isApiInProgress} />
);
}
return (
<View style={[styles.rootContainer]} >
<View style={styles.userAndCompanyInfoContainer}>
<UserInfo
relativeSize={userInfoRelativeSize}
userInfo={{
userId: activity.hostId,
displayName: activity.hostDisplayName,
profileImageUrl: activity.profileImageUrl
}}
/>
<CompanyInfo
relativeSize={userInfoRelativeSize}
Name={activity.hostOrgName} />
</View>
<View style={styles.titleContainer}>
<FeedCardTitle>{activity.title}</FeedCardTitle>
</View>
<View style={styles.descriptionContainer}>
<AppText style={styles.descriptionText}>{activity.description}</AppText>
</View>
<View style={styles.locationContainer}>
<LocationCard locationDescription={activity.locationDescription} />
</View>
<View style={styles.dateAndTimeContainer}>
<FeedCardDate dateDay={activity.dateDay} dateMonth={activity.dateMonth} />
<TimeInfo time={activity.tentativeTime} />
</View>
<View style={styles.buttonContainer}>
<ParticipantsSnapshot
participantsImages={[...activityData.participantsImages]} />
{getButtonComponent()}
</View>
</View >
);
}
The behaviour I am unable to relate with is - When a button in pressed in the FeedCard, it calls the method triggerJoinActivityMutation or triggerOptOutMutation. I am setting the state isApiInProgress to true, which is used by the button component to show the loading animation. But whenever setIsApiInProgress is called in any of these 2 methods, it also re-renders the FeedScreen. Ideally the state change only moves downwards (what I have learned) then why does the feed screen reloads ?
I know this because the moment I comment all setIsApiInPogress method calls, things start working the way as expected, the FeedScreen never re-renders
My understanding is as follows - Feedscreen renders a list of FeedCards -> which in turn uses BorderedButton. Bordered button uses a state(isApiInProgress) which belongs to FeedCard. So when the state(isApiInProgress is updated) it should re-render the FeedCard and BorderedButton and not the FeedScreen.
Can anyone help me understand this behaviour. I tried exploring the web but could not understand the root cause of this behaviour.
Share Improve this question asked Jan 19 at 21:10 amit guptaamit gupta 611 silver badge4 bronze badges1 Answer
Reset to default 0This is not particular to React Native; it is just normal React behavior.
If state changes in a component, React will always re-render it. Even if the state isn't being "used" by the component (i.e., just passed down to a child).
As a trivial example, the following component re-renders every time the button is pressed, even though "state" isn't actually being used anywhere:
const Component = () => {
const [state, setState] = useState({});
return <button onClick={() => setState({})}>Press me</button>;
};
So calling setIsApiInProgress is expected to re-render the screen. It shouldn't cause significant performance issues as long as the rest of your screen is designed well.
本文标签： react nativeWhy is child component rerendering parent componentStack Overflow
版权声明：本文标题：react native - Why is child component re-rendering parent component - Stack Overflow 内容由网友自发贡献，该文观点仅代表作者本人， 转载请联系作者并注明出处：http://www.betaflare.com/web/1742058895a2418463.html， 本站仅提供信息存储空间服务，不拥有所有权，不承担相关法律责任。如发现本站有涉嫌抄袭侵权/违法违规的内容，一经查实，本站将立刻删除。
发表评论