Keep Coding

So I have a component that adds a * at the beginning of typed in text that looks like this:
export default class MyTextField extends Component {
constructor() {
super();
this.state = {
value: '',
};
}
static propTypes = {
onChange: PropTypes.func,
value: PropTypes.string
}
addSymbol(newValue, symbol) {
return newValue.indexOf(symbol) === -1 ? `${symbol}${newValue}` : newValue;
}
change(input, newValue) {
console.log(`I am the parent wit newValue ${newValue}.`);
this.setState({
value: this.addSymbol(newValue, '*')
});
}
render() {
const {
onChange, // eslint-disable-line no-unused-vars
...other
} = this.props;
return (
<TextField
value={this.state.value}
onChange={this.change.bind(this)}
{...other } >
</TextField >
);
}
}
Now I use MyTextFieldin another component like this:
<MyTextField
style={styleTextFields}
floatingLabelText='Add text'
type='text'
/>
Now when I start typing everything works great.
If I change the code above and add value='test' prop on MyTextField everything breaks. It appears its because I added a prop to TextField which can not be overwritten by MyTextField value={this.state.value}.
So how can I add prop value and still add a * at the beginning of the typed text?
The other part is if the user adds their own onChange, how can I get both MyTextField and the component using MyTextField onChange events to get called?
=======Beginning of Edit 1===============
#Patrick - I have made tweaks based on your comment and the first part is now working. So I can type in <TextField /> and I see the changes.
The changes are below:
export default class MyTextField extends Component {
constructor(props) {
super();
this.state = {
value: props.value ? this.addSymbol(props.value.toString(), '*') : ''
};
}
static propTypes = {
onChange: PropTypes.func,
value: PropTypes.string
}
addSymbol(newValue, symbol) {
return newValue.indexOf(symbol) === -1 ? `${symbol}${newValue}` : newValue;
}
change(input, newValue) {
console.log(`I am the parent wit newValue ${newValue}.`);
this.setState({
value: this.addSymbol(newValue, '*')
});
}
render() {
const {
value, // eslint-disable-line no-unused-vars
onChange, // eslint-disable-line no-unused-vars
...other
} = this.props;
return (
<TextField
value={this.state.value}
onChange={this.change.bind(this)}
{...other } >
</TextField >
);
}
}
I am not sure how to make the onChange tweak because you are not supposed to modify component state?
I also did try this in the render() function which does not work:
addSymbol(newValue, symbol) {
return newValue.indexOf(symbol) === -1 ? `${symbol}${newValue}` : newValue;
}
change(input, newValue) {
console.log(`I am the parent wit newValue ${newValue}.`);
this.setState({
value: this.addSymbol(newValue, '*')
});
}
render() {
const {
value, // eslint-disable-line no-unused-vars
onChange, // eslint-disable-line no-unused-vars
...other
} = this.props;
return (
<TextField
value={this.addSymbol(this.state.value, '*')}
{...other } >
</TextField >
);
}
Anyway, thank you for your help.
=======Ending of Edit 1===============
=======Beginning of Edit 2===============
I fixed the onChange event problem by adding my own event called onNewValueChange and calling it in the onChange. Here is the final code:
export default class MyTextField extends Component {
constructor() {
super();
this.state = {
value: props.value ? this.addSymbol(props.value.toString(), '*') : ''
};
}
static propTypes = {
onNewValueChange: PropTypes.func,
value: PropTypes.string
}
addSymbol(newValue, symbol) {
return newValue.indexOf(symbol) === -1 ? `${symbol}${newValue}` : newValue;
}
change(input, newValue) {
const value = value: props.value ? this.addSymbol(props.value.toString(), '*') : '';
this.setState({
value: value
});
if(this.props.onNewValueChange) {
this.props.onNewValueChange(value);
}
}
render() {
const {
onNewValueChange, // eslint-disable-line no-unused-vars
...other
} = this.props;
return (
<TextField
value={this.state.value}
onChange={this.change.bind(this)}
{...other } >
</TextField >
);
}
}
Now I use MyTextField in another component like this:
<MyTextField
style={styleTextFields}
floatingLabelText='Add text'
type='text'
onNewValueChange={(newValue) => console.log(newValue) }
/>
#Patrick thank you for your help getting me in the right direction.
=======Ending of Edit 2===============

In general, I think this pattern of omitting props before passing everything else inside a component is confusing, at least for me. Being explicit as possible should always be a priority.
If I understood you correctly, the expected behavior is as follows:
You can pass a default text, this text should be prefixed with a * by your component.
You can modify the text, but no matter how you modify it, it should always be prefixed with a * - so an empty string should just be *.
I've created this fiddle which hopefully does what you meant : https://jsfiddle.net/69z2wepo/78041/
The key concept is to separate between props and state, a prop is passed only once, and should really be responsible for the initial state of your
Here's the two classes I created :
class Input extends React.Component{
render(){
return (<input onChange={this.props.onChange} value={this.props.value}/>)
}
}
class WrappedInput extends React.Component{
constructor(props){
super();
let val = props.value || '';
this.state = {
value : this.addSymbol(val,'*')
}
}
handleChange(e){
let newVal = e.target.value;
this.setState({value:this.addSymbol(newVal,'*')});
}
addSymbol(newValue, symbol) {
return newValue.indexOf(symbol) === -1 ? `${symbol}${newValue}` : newValue;
}
render(){
return (<Input onChange={this.handleChange.bind(this)} value={this.state.value}/>)
}
}