问题
I created a reactJs page that allows an admin add a user to a platform. Now, instead of submitting the form for each new user, the admin can add as many users as possible before submitting the form. By default, one table row containing input fields is displayed and then on click of the add button, a new row is added and the admin can fill the necessary details.
I want to add an onChange event to the input fields for each new row. I don't know how to do as this is quite dynamic. The state will have to change as new rows is added. I don't know how to go about updating this state and adding the onChange event for each field in each row. Here is my existing code:
export default class Admins extends React.Component{
constructor(props){
super(props);
this.state = {
errors : '',
success : '',
rows : [1]
}
this.addRow = this.addRow.bind(this);
this.fetchRows = this.fetchRows.bind(this);
this.removeRow = this.removeRow.bind(this);
}
addRow(){
var last = this.state.rows[this.state.rows.length-1];
var current = last + 1;
this.setState({
rows : this.state.rows.concat(current)
});
}
removeRow(index){
var array = this.state.rows;
array.splice(index, 1)
this.setState({
rows : array
})
}
fetchRows(){
return this.state.rows.map((row, index) => (
//console.log(row, index)
<tr key={row}>
<td className="text-center">
<button type="button" onClick={(e)=> this.removeRow(index)} data-toggle="tooltip" className="btn btn-xs btn-danger"
data-original-title=""><i className="fa fa-trash"></i>
</button>
</td>
<td>
<input type="text" className="form-control" onChange={}/>
</td>
<td>
<input type="text" className="form-control" onChange={}/>
</td>
<td>
<input type="text" className="form-control" onChange={}/>
</td>
</tr>
));
}
render(){
return(
<div>
<Top/>
<SideBar/>
<div className="breadcrumb-holder">
<div className="container-fluid">
<ul className="breadcrumb">
<li className="breadcrumb-item"><Link to="/">Dashboard</Link></li>
<li className="breadcrumb-item active">Admins</li>
</ul>
</div>
</div>
<section className="forms">
<div className="container-fluid">
<header>
<h3 className="h5 display">Admins</h3>
</header>
<div className="row">
<div className="col-lg-6">
<h5 className="text-danger">{this.state.errors}</h5>
<h5 className="text-success">{this.state.success}</h5>
</div>
</div>
<div className="row">
<div className="col-lg-6">
<div className="card">
<div className="card-header d-flex align-items-center">
<h5></h5>
</div>
<div className="card-body">
<table className="table table-bordered">
<thead>
<tr>
<th width="5%">Actions</th>
<th>Name</th>
<th>Email</th>
<th>Password</th>
</tr>
</thead>
<tbody>
{this.fetchRows()}
<tr>
<td className="text-center">
<button type="button" onClick={this.addRow} data-toggle="tooltip" className="btn btn-xs btn-primary"
data-original-title=""><i className="fa fa-plus"></i>
</button>
</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
</div>
</div>
</section>
</div>
);
}
}
回答1:
You could create a method onChange that takes in the event and the index of the row that got changed, and use the name and the value of the input that changed combined with the index of the row in the array to figure out what field to update.
Example
class Admins extends React.Component {
state = {
errors: "",
success: "",
rows: []
};
addRow = () => {
this.setState(previousState => {
return {
rows: [...previousState.rows, { name: "", email: "", password: "" }]
};
});
};
removeRow = index => {
this.setState(previousState => {
const rows = [...previousState.rows];
rows.splice(index, 1);
return { rows };
});
};
onChange = (event, index) => {
const { name, value } = event.target;
this.setState(previousState => {
const rows = [...previousState.rows];
rows[index] = { ...rows[index], [name]: value };
return { rows };
});
};
render() {
return (
<div>
<div className="breadcrumb-holder">
<div className="container-fluid">
<ul className="breadcrumb">
<li className="breadcrumb-item active">Admins</li>
</ul>
</div>
</div>
<section className="forms">
<div className="container-fluid">
<header>
<h3 className="h5 display">Admins</h3>
</header>
<div className="row">
<div className="col-lg-6">
<h5 className="text-danger">{this.state.errors}</h5>
<h5 className="text-success">{this.state.success}</h5>
</div>
</div>
<div className="row">
<div className="col-lg-6">
<div className="card">
<div className="card-header d-flex align-items-center">
<h5 />
</div>
<div className="card-body">
<table className="table table-bordered">
<thead>
<tr>
<th width="5%">Actions</th>
<th>Name</th>
<th>Email</th>
<th>Password</th>
</tr>
</thead>
<tbody>
{this.state.rows.map((row, index) => (
<tr key={row}>
<td className="text-center">
<button
type="button"
onClick={e => this.removeRow(index)}
data-toggle="tooltip"
className="btn btn-xs btn-danger"
data-original-title=""
>
<i className="fa fa-trash" />
</button>
</td>
<td>
<input
type="text"
name="name"
className="form-control"
value={row.name}
onChange={e => this.onChange(e, index)}
/>
</td>
<td>
<input
type="text"
name="email"
className="form-control"
value={row.email}
onChange={e => this.onChange(e, index)}
/>
</td>
<td>
<input
type="text"
name="password"
className="form-control"
value={row.password}
onChange={e => this.onChange(e, index)}
/>
</td>
</tr>
))}
<tr>
<td className="text-center">
<button
type="button"
onClick={this.addRow}
data-toggle="tooltip"
className="btn btn-xs btn-primary"
data-original-title=""
>
<i className="fa fa-plus" />
</button>
</td>
</tr>
</tbody>
</table>
</div>
</div>
</div>
</div>
</div>
</section>
</div>
);
}
}
来源：https://stackoverflow.com/questions/51399688/adding-dynamic-states-in-reactjs