Develop Reference

Can't get store value after the value was updated using React

I have a SearchBar component and it has a subcomponent SearchBarItem.
I passed the method handleSelectItem() to subcomponent to dispatch value to store and it works (I saw it from the Redux tool in Chrome).
Then, when I tried to get the value from the method submitSearch(), which I also passed it from the parent component, it shows:
Cannot read property 'area' of undefined.
I'm still not so familiar with React. If someone can help, it will be very appreciated. Thanks in advance.
This is parent component SearchBar:
class SearchBar extends Component {
handleSelectItem = (selectCategory, selectedItem) => {
if (selectCategory === 'areas') {
this.props.searchActions.setSearchArea(selectedItem);
}
}
submitSearch() {
console.log(this.props.area); // this one is undefined
}
render() {
return (
<div className="searchBar">
<SearchBarItem
selectCategory="areas"
name="地區"
options={this.props.areaOptions}
handleSelectItem={this.handleSelectItem}
submitSearch={this.submitSearch}
/>
</div>
);
}
}
const mapStateToProps = state => ({
area: state.search.area,
brandOptions: state.search.brandOptions,
vehicleTypeOptions: state.search.vehicleTypeOptions,
areaOptions: state.search.areaOptions,
});
const mapDispatchToProps = dispatch => ({
searchActions: bindActionCreators(searchActions, dispatch),
});
export default connect(mapStateToProps, mapDispatchToProps)(SearchBar);
This is subcomponent SearchBarItem:
export default class SearchBarItem extends Component {
state = {
showOptions: false,
selectedItem: [],
}
handleSelectItem = (selectedItem) => this.props.handleSelectItem(this.props.selectCategory, selectedItem);
submitSearch = () => this.props.submitSearch();
handleClickCategory = () => {
this.setState({ showOptions: !this.state.showOptions });
}
handleClickItem(option) {
this.setState({
selectedItem: [...this.state.selectedItem, option],
}, () => this.handleSelectItem(this.state.selectedItem));
}
render() {
const options = this.props.options.map((item, index) => (
<div
className={this.state.selectedItem === item ? "searchBarItem＿＿option--active" : "searchBarItem＿＿option"}
key={index}
onClick={() => this.handleClickItem(item)}
>
{item}
</div>
));
const optionBox = (
<div className="searchBarItem＿＿box">
<div
className="searchBarItem＿＿option"
onClick={() => this.handleClickItem('')}
>
不限{this.props.name}
</div>
{options}
<div className="searchBarItem__confirm">
<span>取消</span><span onClick={() => this.submitSearch()} >套用</span>
</div>
</div>
);
return (
<div className="searchBarItem">
<span onClick={() => this.handleClickCategory()} >
{(() => {
switch (this.state.selectedItem.length) {
case 0: return this.props.name;
case 1: return this.state.selectedItem[0];
default: return `${this.state.selectedItem.length} ${this.props.name}`;
}
})()}
</span>
{ this.state.selectedItem.length > 0 ? '' : <Icon icon={ICONS.DROP_DOWN} size={18} /> }
{ this.state.showOptions ? optionBox : '' }
</div>
);
}
}
SearchBarItem.propTypes = {
name: PropTypes.string.isRequired,
selectCategory: PropTypes.string.isRequired,
options: PropTypes.arrayOf(PropTypes.string).isRequired,
handleSelectItem: PropTypes.func.isRequired,
submitSearch: PropTypes.func.isRequired,
};

Your problem caused by the behavior of this pointer in javascript.
By writing the code submitSearch={this.submitSearch} you are actually sending a pointer to the submitSearch method but losing the this pointer.
The method actually defers as MyClass.prototype.myMethod. By sending a pointer to the method MyClass.prototype.myMethod you are not specifying to what instance of MyClass it belongs to (if at all). This is not the most accurate explanation of how this pointer works but it's intuitive explanation, you can read more here about how this pointer works
You have some possible options to solve it:
Option one (typescript/babel transpiler only) - define method as class variable
class MyClass{
myMethod = () => {
console.log(this instanceof MyClass) // true
}
}
this will automatically do option 2 for you
Option two - Bind the method on the constructor
class MyClass{
constructor(){
this.myMethod = this.myMethod.bind(this)
}
myMethod() {
console.log(this instanceof MyClass) // true
}
}
By the second way, you are binding the method to current this instance
Small note, you should avoid doing:
<MyComponent onSomeCallback={this.myCallback.bind(this)} />
Function.prototype.bind returns a new method and not mutating the existing one, so each render you'll create a new method and it has performance impact on render (binding it on the constructor only once as option two, is fine)

Return JSX from component method to render method

I'm still new to React. I'm trying to render a jsx under a condition defined in another method under my class component like so:
isWinner = () => {
let userVotesCount1 = this.state.user1.userVotesCount;
let userVotesCount2 = this.state.user2.userVotesCount;
if (userVotesCount1 > userVotesCount2) {
userVotesCount1++;
this.setState({ user1: { userVotesCount: userVotesCount1 } });
return (
<h3>Winner</h3>
);
}
userVotesCount2++;
this.setState({ user2: { userVotesCount: userVotesCount2 } });
return (
<h3>Loser</h3>
);}
and i'm calling this method inside the render method
<Dialog
open={open}
onRequestClose={this.onClose}
>
<div>
<isWinner />
</div>
</Dialog>
already tried to use replace <isWinner /> for {() => this.isWinner()}and I never get the return from the method. What I am doing wrong? Since I'm dealing with state here I wouldn't know how to do this with outside functions. For some reason this function is not being called ever. Please help!

You're almost there. What you want to do is use the method to set a flag, and then use the flag in the render method to conditionally render.
constructor(props) {
...
this.state = {
isWinner: false,
...
}
}
isWinner() {
...,
const isWinner = __predicate__ ? true : false;
this.setState({
isWinner: isWinner
});
}
render() {
const { isWinner } = this.state;
return isWinner ? (
// jsx to return for winners
) : (
// jsx to return for lossers
)
}

How to use the variable 'document' in react native?

I am trying to capture all click events outside of my SearchBar component so that I can then tell the dropdown menu to close when one clicks out of it. I looked up examples of how to do this online and I need to use the global variable 'document' in javascript. However, it seems react native does not support this. Does anyone know a work around to use the 'document' variable or a react native equivalent?
class Products extends Component {
constructor(props) {
super(props);
this.setWrapperRef = this.setWrapperRef.bind(this);
this.handleClickOutside = this.handleClickOutside.bind(this);
}
setWrapperRef(node) {
this.wrapperRef = node;
}
handleClickOutside(event) {
if (this.wrapperRef && !this.wrapperRef.contains(event.target)) {
alert('You clicked outside of me!');
}
}
componentWillMount() {
this.props.dispatch(getProductList());
}
componentDidMount() {
document.addEventListener('mousedown', this.handleClickOutside);
}
componentWillUnmount() {
document.removeEventListener('mousedown', this.handleClickOutside);
}
render() {
const {isLoading, products} = this.props.products;
if (isLoading) {
return <Loader isVisible={true}/>;
}
return (
<View ref={this.setWrapperRef} style={styles.wrapper}>
<Header/>
<View style={styles.bodyWrapper}>
<ScrollView style={styles.scrollView}>
<ProductsContainer data={{productsList: { results: products }}}/>
</ScrollView>
<SearchBar style={styles.searchBar}/>
</View>
<Footer/>
</View>
);
}
}
function mapStateToProps(state) {
const {products} = state;
return {
products
};
}
export default connect(mapStateToProps)(Products);

You can't use document, it's an object on the window. The above answer is incorrect and hasn't taken into account this platform is React Native (answer has since been removed).
To handle click events, you you need to wrap everything in a TouchableWithoutFeedback.
<TouchableWithoutFeedback
onPress={this.hideSearchBar}
/>
I would add a zIndex style to the TouchableWithoutFeedback and one in styles.scrollView. Make sure the zIndex inside of styles.scrollView is more than the one you added to the TouchableWithoutFeedback.

Using enzyme, How to find a child component in a component react-native

I am new to React-native and enzyme, I am trying to create a custom component here.
I will be displaying an Image based on this.props.hasIcon. I set default props value for hasIcon as true. When I check Image exists in enzyme ShallowWrapper. I am getting false.
tlProgress.js
class TLProgress extends Component {
render() {
return (
<View style={styles.container}>
{this.renderImage}
{this.renderProgress}
</View>
);
}
}
TLProgress.defaultProps = {
icon: require("./../../img/logo.png"),
indeterminate: true,
progressColor: Colors.TLColorAccent,
hasIcon: true,
progressType: "bar"
};
and renderImage() has the Image
renderImage() {
if (this.props.hasIcon) {
return <Image style={styles.logoStyle} source={this.props.icon} />;
}
}
Now, If I check Image exists in enzyme am getting false.
tlProgress.test.js
describe("tlProgress rendering ", () => {
let wrapper;
beforeAll(() => {
props = { indeterminate: false };
wrapper = shallow(<TLProgress {...props} />);
});
it("check progress has app icon", () => {
expect(wrapper.find("Image").exists()).toBe(true); // fails here..
});
});

You are not calling the renderImage function in your render() -- you forgot the brackets, thus it is being interpreted as an undefined variable.
It should be: (I am assuming you want to call renderProgress() and not renderProgress as well)
class TLProgress extends Component {
render() {
return (
<View style={styles.container}>
{this.renderImage()}
{this.renderProgress()}
</View>
);
}

You're searching for a tag called 'Image' instead of looking for your component Image
It should be :
import Image from '../Image';
wrapper.find(Image) //do your assert here

React - Child onClick event doesn't trigger when binding parameters

My problem is the following.
I have a "BookShelf" component which contains a "Book" list.
The parent (bookshelf) manage in its state a "selectedBook" property.
When clicking on one child (book), I would like to update its parent selectedBook property.
To achieve this, I use a function defined in the parent properties.
But this method is never trigerred (I tried with a console.log('something') but it never shows.
See my code below :
setSelectedBook(index) {
this.setState({
selectedBook: index
})
},
getInitialState() {
return {
books: [],
selectedBook: null
}
},
componentDidMount() {
let component = this
$.ajax({
url: 'data/books.json',
success (data) {
component.setState({
books: data
})
},
error (err) {
console.log(err)
}
})
},
render() {
let component = this
var bookList = this.state.books.map(function(book, index) {
let selectBook = component.setSelectedBook.bind(component, index)
return (
<Book onClick={selectBook} data={book} key={index} />
)
})
return <div className="book-shelf">
{bookList}
</div>
}
Thanks in advance !

Here is a simple example for you. Also fiddle
You should pass your onClick event as a props to child component, once child component gets it, it will call a callback and pass an id as an agrument to the callback (like i have below).
class Book extends React.Component {
constructor(props){
super(props);
this.handleClick = this.handleClick.bind(this);
}
handleClick(){
this.props.click(this.props.id)
}
render(){
return <li onClick={this.handleClick}>{this.props.id} - {this.props.name}</li>
}
}
class BookShelf extends React.Component{
constructor(){
super();
this.onClick = this.onClick.bind(this)
}
onClick(id){
console.log(id)
}
render(){
return <ul> // of course you may use Array.map functions, it's just for example
<Book click={this.onClick} id={1} name={'hello'}/>
<Book click={this.onClick} id={2} name={'world'}/>
</ul>
}
}
React.render(<BookShelf />, document.getElementById('container'));
Also i suggest look at this article Communicate Between Components, it will be useful for you.
Thanks

select method return anonymous function as value.
<Book onClick={this.selectBook(index)} data={book} key={index} />
selectBook (index){
return ((() => {
console.log(" selectBook fired" );
component.setState({selectedBook:index});
}).bind(component,index))
}