What is the difference between these two View components? - react-native

I am looking at react-360 and react-native code and found the following examples concerning the View component.
class ViewColoredBoxesWithText extends Component {
render() {
return (
<View style={{flexDirection: 'row', height: 100, padding: 20}}>
<View style={{backgroundColor: 'blue', flex: 0.3}} />
<View style={{backgroundColor: 'red', flex: 0.5}} />
<Text>Hello World!</Text>
</View>
);
}
}
Why are the children View components self closing whereas the parent View component is not.

As for the parent <View> you cannot use self closing because it has to wrap children components between the opening and closing tags.
In case of child <View> you are not wrapping any children within the tag, so you are using open with the choice to use self-closing or separate closing tag. This is the JSX feature same applies for all the tags such as <div>, <p> or other custom elements.
you can get to know about it in more depth JSX in Depth

Because the parent View component has children components while the children View components do not. See this related Stack Overflow question: (React component closing tag)

Related

React Native flex children gone when declaring flex property

My component is extremely simple, I have a <View> component with a flex:1 property.
I have another View inside of that parent View with a property of flex: .5, from my understanding - it should take up 50% of the parent View's height. But it doesn't take up anything, it's gone as if there is no element there. height: "50%" works though.
because of the other view with flex: 1 take the entire space of parent,
flex: 1 means width: 100% or height: 100% of the parent (depends on the flex direction).
Change to flex: .5 for both Views and you will see them in the half and half of parent.
If your code is like the following, it should be working.
<View style={{flex: 1, backgroundColor: 'blue'}}>
<View style={{flex: .5, backgroundColor: 'red'}} />
</View>
Just be aware the component above will affected by its parent View as well. Please check all the flex in parent views.
Also, it is good to provide any of the code in the question to make it easier for debugging.
As per your program you have used only View component inside another View component. also you have added style {flex:1} to parent view and {flex: 0.5} style to child.
Problem : your problem is child view is not taking 50% of the parent using {flex: 0.5}.
Solution : if you want to access 50% of the parent using {flex: 0.5} then you have to add any component like Text component inside of child View etc..
ex:
/**
* Sample React Native App
* https://github.com/facebook/react-native
*
* #format
* #flow strict-local
*/
import React from 'react';
import {
Text,
View,
} from 'react-native';
const App = () => {
return (
<View style={{ flex: 1, flexDirection:'row' }}>
<View style={{ flex: 0.5, backgroundColor: 'red' }}>
<Text>{"Hello"}</Text>
</View>
</View>
);
};
export default App;

Overlapping components of same width and height

Is it possible to implement ReactNative layout containing two components, where 2nd component overlaps 1st one and has the same width, possibly also same height (without hardcoding width/height of course)? It is easy to implement something like that in native Android, but I can't find example for ReactNative. I'd be surprised if it is not possible though.
You could try below
<View style={{ flex: 1 }} >
<View style={{ flex: 1 }}>
// 1st component
<View>
<View style={StyleSheet.absolueFill}>
// 2st component
<View>
<View>

Create a reusable React Native Modal Component

I'm going back to basics with React Native, as I feel overwhelmed. I have been looking for an implementation of a reusable modal component. I'm looking for examples of a reusable Modal component in RN? Thanks in advance
You can find many examples of this on StackOverflow. Still, if you need example I can help you with one example. You have mentioned modal component in your question, right?
Your component will look like this with props. let the name be ModalComponent for this file.
render() {
const { isVisible, message, textValue } = this.props;
return (
<Modal
animationType="slide"
transparent={false}
isVisible={isVisible}
backdropColor={"white"}
style={{ margin: 0 }}
onModalHide={() => {}}>
<View>
<Text>textValue</Text>
<Text>message</Text>
</View>
</Modal>
);
}
so now in your js file you need to import this modalComponent and after that, you need to write as
<ModalComponent
isVisible={true}
textValue={'hi there'}
message={'trying to make a basic component modal'}/>
Hope this will help for you
EDIT:
Create seperate components that you want to render inside modal. for Ex: component1.js, component2.js, component3.js with props
component1.js:
render(){
const { textVal, message } = this.props
return (
<View>
<Text>{textVal}</Text>
<Text>{message}</Text>
</View>
)
}
now in ModalComponent
render() {
const { first, second, third, isVisible, component1Text, component1Message } = this.props;
<Modal
animationType="slide"
transparent={false}
isVisible={isVisible}
backdropColor={"white"}
style={{ margin: 0 }}
onModalHide={() => {}}>
<View>
{first && <component1
textValue= component1Text
message= component1Message />}
{second && <Component2 />}
{third && <Component2 />}
</View>
</Modal>
In this way, you can achieve it within the single modal.
You will make a component like this giving the parent component all the liberty to change it through props.
render() {
const { isVisible, message, textValue, animationType, backDropColor, style, onModalHide, children } = this.props;
return (
<Modal
animationType= {animationType || 'slide'}
transparent={transparent || false}
isVisible={isVisible || false}
backdropColor={backdropColor || "white"}
style={[modalStyle, style]}
onModalHide={onModalHide}>
{children}
</Modal>
);
}
Then in your parent component, you need to import this component like this:
import ModalComponent from '../ModalComponent'; //path to your component
<ModalComponent isVisible={true}>
<View>
//any view you want to be rendered in the modal
</View>
</ModalComponent>
I had a lot of troubles using react-native modal, sometimes i started the app and could not close it even when i set the isVisible prop to false, it is even worst on IOs, i did a research and these packages are not being maintained properly.
You will save a lot of time by using a top-level navigator like is recommended in the modal docs: https://facebook.github.io/react-native/docs/modal.
I tried https://github.com/react-native-community/react-native-modal but had the same problems because its an extension of the original react-native modal.
I suggest you to use the react-navigation modal as described here: https://reactnavigation.org/docs/en/modal.html#docsNav
You can refer the following code to write Modal component once and use multiple times.
Write once:
import React, { Component } from 'react';
import { View, Text, Button, Modal, ScrollView, } from 'react-native';
export class MyOwnModal extends Component {
constructor(props) {
super(props);
this.state = {
}
render() {
return(
<Modal
key={this.props.modalKey}
transparent={this.props.istransparent !== undefined ? true : false}
visible={this.props.visible}
onRequestClose={this.props.onRequestClose}>
<View style={{
//your styles for modal here. Example:
marginHorizontal: width(10), marginVertical: '30%',
height: '40%', borderColor: 'rgba(0,0,0,0.38)', padding: 5,
alignItems: 'center',
backgroundColor: '#fff', elevation: 5, shadowRadius: 20, shadowOffset: { width: 3, height: 3 }
}}>
<ScrollView contentContainerStyle={{ flex: 1 }}>
{this.props.children}
</ScrollView>
</View>
</Modal>
);
}
}
Now,
You can call your Modal like following example: (By doing this, you avoid re-writing the Modal and its outer styles everytime!)
Example
<MyOwnModal modalKey={"01"} visible={true} onRequestClose={() =>
this.anyFunction()} istransparent = {true}>
<View>
// create your own view here!
</View>
</MyOwnModal>
Note: If you are in using different files don't forget to import , and also you can pass the styles as props.
(You can create/customise props too based on your requirement)
Hope this saves your time.
Happy coding!
I am a contributor of react-native-use-modal.
This is an example of creating a reusable modal in a general way and using react-native-use-modal: https://github.com/zeallat/creating-reusable-react-native-alert-modal-examples
With react-native-use-modal, you can make reusable modal more easily.
This is a comparison article with the general method: https://zeallat94.medium.com/creating-a-reusable-reactnative-alert-modal-db5cbe7e5c2b

Stacking Order: How to render component so it appears on top of parents' sibling who renders afterwards

I'm having some problems with zIndex and position whilst styling a drop down list (react-native-menu). I want to make the drop down list appear on top of all other components on this scene when it's clicked. I'm trying to use zIndex and position but maybe not doing it correctly?
In my code (below), I'm rendering a hierarchy where Card > CardSection > various subcomponents of each. The drop down list consists of the components MenuContext (config) and TopNavigation (main drop down list).
return (
<Card>
<CardSection style={{zIndex: 2}}>
<View style={thumbnailContainerStyle}>
<Image style={thumbnailStyle}
source={{ uri: "" }}
/>
</View>
<View style={headerContentStyle}>
<Text style={headerTextStyle}>Tam</Text>
<Text>tam#tam</Text>
</View>
<MenuContext style={{ flex:1, zIndex:6, position:'absolute', flexDirection: 'column', alignItems: 'flex-end' }} >
<TopNavigation/> //this is
</MenuContext>
</CardSection>
<CardSection style={{zIndex: 1}}>
<Text style={{zIndex: 2}}>{props.post.body}</Text>
</CardSection>
</Card>
)
So the drop down is a child of the first CardSection. I've got it to appear over it's own parent CardSection but I can't get it to appear on top of the second CardSection that renders after. So I can't get it to show on top of it's parent's sibling.
I'm reluctant to use some plugin or workaround.
Any ideas? Thanks!!
So what was making it so hard to render the popup menu above things on the z-axis was the sibling of it's parent. So what helped me get the results I needed was looking more macro and moving <ContextMenu/> higher in the component hierarchy, out of this component altogether and into it's parent.
I should have inferred this since the docs for the original package I used had ContextMenu in the entry point to the app and comments such as:
// You need to place a MenuContext somewhere in your application,usually at the root.
// Menus will open within the context, and only one menu can open at a time per context.
My mistake was getting lost in the micro world of zIndex and position and assuming that what looked like a styling problem should be solved with a styling solution. I forgot about the bigger picture.

Why my react native navigation bar's text not on the vertical center?

I use the Navigator.NavigationBar component to make a navbar, but the text not vertical centering.
Like this:
How can I solve this?
I just ran into this issue too. The solution:
<Navigator.NavigationBar
routeMapper={{
Title: (route, navigator, index, navState) =>
{
return (
<View style={{
justifyContent: 'center',
flex: 1
}}>
<Text style={{color: 'white'}}>Candidates</Text>
</View>
);
},
}}
/>
So basically make sure there's a parent wrap on your navbar elements filling the navbars height (the flex: 1 rule) and vertically center its contents with justifyContent: 'center'.
I've done the styles inline for this example, but of course it'd be more efficient to get those from a StyleSheet object.