组件正在文本类型的不受控制的输入更改为 ReactJS 的受控错误
问题说明
警告:组件正在更改要控制的文本类型的不受控制的输入.输入元素不应从不受控切换到受控(反之亦然).在组件的生命周期内决定使用受控输入元素还是不受控输入元素.*
Warning: A component is changing an uncontrolled input of type text to be controlled. Input elements should not switch from uncontrolled to controlled (or vice versa). Decide between using a controlled or uncontrolled input element for the lifetime of the component.*
以下是我的代码:
constructor(props) {
super(props);
this.state = {
fields: {},
errors: {}
}
this.onSubmit = this.onSubmit.bind(this);
}
....
onChange(field, e){
let fields = this.state.fields;
fields[field] = e.target.value;
this.setState({fields});
}
....
render() {
return(
<div className="form-group">
<input
value={this.state.fields["name"]}
onChange={this.onChange.bind(this, "name")}
className="form-control"
type="text"
refs="name"
placeholder="Name *"
/>
<span style={{color: "red"}}>{this.state.errors["name"]}</span>
</div>
)
}
正确答案
原因是，在你定义的状态下:
The reason is, in state you defined:
this.state = { fields: {} }
fields 作为一个空白对象，所以在第一次渲染时，this.state.fields.name 将是 undefined，并且输入字段将得到它的值:
fields as a blank object, so during the first rendering this.state.fields.name will be undefined, and the input field will get its value as:
value={undefined}
因此，输入字段将变得不受控制.
Because of that, the input field will become uncontrolled.
在输入中输入任何值后，状态中的 fields 将更改为:
Once you enter any value in input, fields in state gets changed to:
this.state = { fields: {name: 'xyz'} }
此时输入字段被转换为受控组件；这就是您收到错误的原因:
And at that time the input field gets converted into a controlled component; that's why you are getting the error:
组件正在将文本类型的不受控制的输入更改为控制.
A component is changing an uncontrolled input of type text to be controlled.
可能的解决方案:
1- 将状态中的 fields 定义为:
1- Define the fields in state as:
this.state = { fields: {name: ''} }
2- 或者使用 短路评估像这样:
2- Or define the value property by using Short-circuit evaluation like this:
value={this.state.fields.name || ''} // (undefined || '') = ''
这篇好文章是转载于：学新通技术网
