i have a prent comp and a child cmponent. as follows
parent
export class ExpressionMenu extends Component {
constructor(props) {
super(props)
}
state = {
apiArray: [],
}
updateStateFromChild = (arrayType, propertyType, value) => {
let { apiArray } = this.state
let currentArray = []
let idx = apiArray.findIndex((q) => q.id === id)
currentArray = apiArray
switch(propertyType) {
case 'updateObject': {
currentArray = value
break;
}
}
this.setState({
apiArray: currentArray
})
}
render () {
const {
apiArray
} = this.state
return (
<React.Fragment>
<div >
<div>
<ApiPanel
apiArray={apiArray}
updateStateFromChild={this.updateStateFromChild}
/>
</div>
</div>
</React.Fragment>
)
}
}
ExpressionMenu.propTypes = {
styleOverride: PropTypes.object,
eventHandler: PropTypes.func,
};
export default ExpressionMenu;
child
export class ApiPanel extends Component {
constructor(props) {
super(props),
}
removeApi = (id) => {
let { apiArray } = this.props
apiArray = apiArray.filter((q) => q.id !== id);
this.props.updateStateFromChild('api', 'updateObject', apiArray)
};
addApi = () => {
let { apiArray } = this.props
const id = uniqid();
let obj = {}
obj.id = id
apiArray.push(obj)
this.props.updateStateFromChild('api', 'updateObject', apiArray)
};
render() {
const { apiArray } = this.props
return (
<React.Fragment>
{
apiArray.map((apiObj, i) =>
<div key={i} >
<span onClick={() => this.removeApi(apiObj.id) } className={[classes.deleteRow,'material-icons'].join(' ')}>
close
</span>
<div>
<label><b>Hi</b></label>
</div>
<div onClick={this.addApi}>+Add Api</div>
}
</React.Fragment>
)
}
}
ApiPanel.propTypes = {
apiArray: PropTypes.array,
updateStateFromChild: PropTypes.func
}
export default ApiPanel
Now when i call addApi(), it updates the parent but doesnt rerenders the child. But when i call removeApi() , it updates parent as well as rerenders the child component properly.
in the first case when i manually reload the componnt i can see the change.
Dont understand why this is happening
Try to change your addApi function.
addApi = () => {
let { apiArray } = this.props
this.props.updateStateFromChild('api', 'updateObject', [...apiArray, {id : uniqid()} ])
};
You need to return an enriched copy of your array
Whenever we are updating the stating using arrays, objects. We need to always create a new array [...array], a new object {...obj}. Because if we update value in the array or obj without creating it won't change the reference value hence it assumes the state is not update and won't re-render.