React: Changing parent state not rendering child - reactjs

Question

I am extremely new to react and am building a simple todo list app. I am trying to edit data from my child component and send it back to my parent. When I am printing console logs the parent state seems to be getting set correctly, but the child elements are not refreshing. Am I doing something conceptually wrong here?
I have tried to share the entire code as I am not sure whether it is correct conceptually. I am new to JS. When the handleSave() and handleComplete() are called i can see correct values getting returned and set to my PArent State, but there is no refresh of the child components.
Below is my Parent class code.
class App extends Component {
state = {
taskList: [
]
};
saveEventHandler = data => {
console.log("I am in saveEventHandler");
var uniqid = Date.now();
const taskList = [...this.state.taskList];
taskList.push({
id: uniqid,
taskDescText: data,
isFinished: false
});
console.log(taskList);
this.setState({'taskList':taskList});
};
deleteEventHandler = (index) => {
const taskList = [...this.state.taskList];
taskList.splice(index,1)
this.setState({'taskList':taskList});
}
editEventHandler = (index,data) => {
var uniqid = Date.now();
console.log("In edit event handler")
console.log(data)
console.log(index)
const taskList = [...this.state.taskList];
taskList[index] = {
id: uniqid,
taskDescText: data,
isFinished: false
}
this.setState({'taskList':taskList});
console.log(this.state.taskList)
}
handleComplete = (index) => {
console.log("In complete event handler")
const taskList = [...this.state.taskList];
const taskDescriptionOnEditIndex = taskList[index]
taskDescriptionOnEditIndex.isFinished = true
taskList[index] = taskDescriptionOnEditIndex
this.setState({'taskList':taskList});
console.log(this.state.taskList)
}
render() {
return (
<div className="App">
<h1>A Basic Task Listing App </h1>
<CreateTask taskDescription={this.saveEventHandler} />
{this.state.taskList.map((task, index) => {
return (
<Task
taskDescText={task.taskDescText}
taskCompleted={task.isFinished}
deleteTask={() => this.deleteEventHandler(index)}
editTask={(editTask) => this.editEventHandler(index,editTask)}
handleComplete={() => this.handleComplete(index)}
editing='false'
/>
);
})}
</div>
);
}
}
export default App;
and my child class code
export default class Task extends React.Component {
state = {
editing : false
}
notCompleted = {color: 'red'}
completed = {color: 'green'}
textInput = React.createRef();
constructor(props) {
super(props);
this.state = props
}
handleEdit = () => {
this.setState({editing:true});
}
handleSave = () => {
this.props.editTask(this.textInput.current.value);
this.setState({editing:false});
};
editingDiv = (<div className = 'DisplayTask'>
<span className='TaskDisplayText' style={!this.props.taskCompleted ? this.notCompleted: this.completed}>{this.props.taskDescText} </span>
<button label='Complete' className='TaskButton' onClick={this.props.handleComplete}> Complete</button>
<button label='Edit' className='TaskButton' onClick={this.handleEdit}> Edit Task</button>
<button label='Delete' className='TaskButton' onClick={this.props.deleteTask}> Delete Task</button>
</div> );
nonEditingDiv = ( <div className = 'DisplayTask'>
<input className='TaskDescEditInput' ref={this.textInput}/>
<button label='Save' className='TaskButton' onClick={this.handleSave} > Save Task</button>
<button label='Delete' className='TaskButton' onClick={this.props.deleteTask}> Delete Task</button>
</div>);
render() {
return (
!this.state.editing ? this.editingDiv : this.nonEditingDiv
)
};
}

Answer 1

Move your editingDiv and nonEditingDiv definitions inside render() method. Since you're defining them as instance variables, they're initialized once, and never get re-rendered again with new prop values.
By moving them to render() method, render() which is called every time when there's a prop update will pick up the new prop values.