I know this is a stupid question.
I have a component lets call it Component that is used in several screens for Example Screen1,Screen2,...
And in the Component I am navigating to a new Screen when the user click a button, lets call it ImagePicker.
my Question is how do I go back and pass a parameter( in this case image data) and get it back in the Component
I tried using navigation.goBack({img: image}) but that didn't work. I also can't use navigation.navigate('Screen') since my functions are in the Component component.
So what is the best solution for my problem ?
We cannot pass any params to the goBack method.
If we have to do so then, we can use the navigate method to navigate to the back screen, and using this method we can pass the params to the previous screen.
For ex.
navigation.navigate('PrevScreenName', {key: value})
Check out the official docs for the react-navigation.
React Navigation
If I understand your problem well, just do
navigation.navigate('Screen', {img: image})
instead of navigation.goBack({img: image}) and it should work
In the component code, I would pass along a callback function to the image picker screen
handleImageData = (data) =>
{
// do whatever
}
...
navigation.navigate('ImagePickerScreen',{mycallback:this.handleImageData});
and then in the screen code just call it like
this.props.route.params.mycallback(data);
navigation.goBack();
Related
I would like to know if it's possible to set the state to the initial state values whenever we press back the button in the tabBar ? At the moment, when I leave the tabBar and come back after a few navigation in the app, the infos that the user enter in TextField persist.
Thanks !
You could use React hooks to achieve similar results to lifecycle methods in class functions.
The useEffect method runs on component render. You can set the state in there.
const [currentState, setCurrentState] = useState(null);
useEffect(()=>{
// This will run after 1st render
setCurrentState("");
},[]);
I have a button on my header right that open up a drop down component. The component allow user to make some selection and apply it after the user hit the 'apply' button.
After the apply button pressed, it should be able to pass the value back to the 'main screen' component. How do I pass the value back to the 'main screen' ?
This is my interface , if you're wondering what I'm trying to do.
edit
I tried to pass in the useState function to the header component to update the state after the apply button pressed by passing it using the setParam from react navigation props. Is there any other better way to get the value ??
You can do it simply like:
props.navigation('Home', { state: SOME_VALUE });
Here is the react navigation doc to do this.
React navigation passing params to previous screen
Or you can use redux store.
I am using react native for development and i am using functional component for development. but i am facing problem in it. As i am getting callback from function and saving it in a state and i want to that component will render again. but component is not rendering again. Please check and provide me detail in
callBackfn = (callback) => {
this.setState({ infomationtosend: callback });
}
this is working fine as if i will print it on console get state correct output. but as it again goes in the ComponentTreat it doesn't render component again. i also tried useEffect but not working. can anyone provide me solution.
<Swiper
from={0}
>
<ComponentTreat
detailsend={this.state.infomationtosend}
appName={"sentText"}
CallBack={(callback) => this.callBackfn(callback)}
/>
</Swiper>
problem in swiper duw to swiper component is not refreshing.
Functional Component state change works like this:
// Inside parent component
const [info, setInfo] = useState(initalValue);
Then to use it in a callback we use closures to access it instead of using this keyword.
function callback(newValue) {
setInfo(newValue);
}
And pass it accordingly to the child props.
Also, checkout useCallback() if you use a lot of callbacks.
I'm developing a react-native / redux app with a bottom-tab-navigator similar to the example at https://reactnavigation.org/docs/en/tab-based-navigation.html#customizing-the-appearance. My screens all connect to a Redux store and display shared data, however I'd like at least one of these screens to ignore the current data in the store and instead re-initialize this data each time it's navigated to (instead of continuing to display the data in whatever state it was last left in).
The screen has a method to do this, but I can't figure out how to call it after the first time the screen is rendered (e.g. from the constructor or componentDidMount() method). I can't call it from the render() method as this causes a "Cannot update during an existing state transition" error.
I need my navigator to somehow cause my HomeScreen.initializeData() method to be invoked each time the Home icon is pressed, but how do I do this?
HomeScreen.js:
initializeData() {
this.props.resetData(initialValue);
}
const initialValue = ...
(resetData() is a dispatch function that re-initializes the Redux store).
Updating state from render() would create an infinite loop. Also, you don’t want to run your state update every time the component re-render, only when the tab button is pressed. This tells me that the proper place to make your state update is some onPress function on the tab button.
So the question now relies on how to implement some onPress function on a tab button. I believe this answer this question:
Is there an onPress for TabNavigator tab in react-navigation?
So I found an answer, it's a little more complicated than might be expected: As Vinicius has pointed out I need to use the tabBarOnPress navigation option, but I also need to make my dispatch function available to this navigation option.
To do this I found I need to pass a reference to my dispatch function (which is available as a property of my screen) into the navigation option, so I've used navigation params to do this and here's what I've ended up with:
HomeScreen.js:
componentDidMount() {
initializeData(this.props);
this.props.navigation.setParams({ homeProps: this.props });
}
export const initializeData = (homeProps) => {
homeProps.resetData(initialValue);
};
const initialValue = ...
AppNavigator.js:
tabBarOnPress: ({navigation, defaultHandler}) => {
const routeName = navigation.state.routeName;
if (navigation.state.params === undefined) {
// no params available
} else if (routeName === 'Home') {
let homeProps = navigation.getParam('homeProps', null);
initializeData(homeProps);
} else if (routeName === ...
...
}
defaultHandler();
}
Notes:
I'm passing props as a navigation param rather than my dispatch function (which also works) as it's more flexible (e.g. it makes all of my dispatch functions available).
initializeData() is called both during construction of HomeScreen (for the first time the screen is displayed) and from the navigation icon (for subsequent displays of the screen).
It's necessary to check that params is defined within the navigation option as it'll be undefined the first time the screen is displayed (as screen construction has yet to occur). This also makes it necessary to call initializeData() during screen construction.
I have a snack setup:
https://snack.expo.io/#sj458147/view-not-scrolling
when you click show modal -> Click next button the View horizontally scrolls (animated), which then displays an image carousel. Now when you click an image, the View should horizontally scroll again but I get the error undefined is not an object. The error lies within the file:
SliderEntry.js
select = () => {
this.MyScrollView.current.moveToPage(3);
};
any help resolving the issue would be appreciated. Thanks in advance
You have MyScrollView ref in ShowModal. There are 2 ways:
Not recommend: Pass MyScrollView ref as props to Slider, then pass to SliderEntry
Recommend: create a callback as props in SliderEntry. Callback to Slider, then callback to ShowModal
Pass your function in props to other components and then access these functions from your another component.
You can find the answer here
React : Pass function to child component