我有一个简单的 react 组件,其中包含一个表单
。在这个 form
中,用户有一个搜索框可以找到用户。
为了获得有效的表单,必须有至少 3 个但不超过 6 个用户。
因此,我添加了一个隐藏字段(被周围的 display:none; div 隐藏),其中包含已添加用户的数量。 如果当前号码无效,这将显示错误消息。
以下代码经过简化,但显示了我遇到的主要问题。
在我的渲染调用中我有:
render():JSX.Element {
return (
<form>
<ValidatableInput
input={<Input type="number" value={this.state.users.length.toString()} min={3} max={6} getRef={(el: HTMLInputElement) => this.testElement = el} onChange={() => alert("changed...")} />}
minValueMessage={"Currently there are " + this.state.users.length + " users. A minimum of 3 is needed"}
hidden={true} />
<UserSearch onUserSelected={this.handleUserSelected} />
// ...
</form>
);
}
而 UserSearch
是用于搜索用户的组件。这主要是一个触发 handleUserSelected
的自动完成输入:
private handleUserSelected = (selectedElement: IUser) : void => {
// get a copy of the current state
const newState = { ...this.state };
// add the user
newState.users.push(selectedElement);
// thats what I've tried so far
this.testElement.dispatchEvent(new Event("change"));
this.testElement.dispatchEvent(new Event("change", {bubbles: true}));
this.testElement.onchange(new Event("change"));
this.testElement.onchange(new Event("change"), {bubbles: true});
this.setState(newState, () => // here I want to do the triggering as the input has now the new count as value set)
}
但是,控制台根本不显示changed
。
当组件发生其他变化时,如何手动调用/触发变化事件?
这是 ValidatableInput 组件:
export class ValidatableInput extends React.Component<IValidatableInputProps, IValidatableInputState> {
render(): JSX.Element {
const { labelText, input, requiredMessage, maxLengthMessage, minValueMessage, hidden } = this.props;
input.props.onInvalid = this.handleInvalid;
input.props.onChange = this.handleChange;
if (hidden) {
// set height to 0
}
return (
<FormGroup row >
<Label for={input.props.name} md={3}>{!hidden && labelText}</Label>
<Col md={9}>
<div>
{input}
{this.state.validityState.valueMissing && <div className={classNames("invalid-feedback")}>{requiredMessage || "This field is required"}</div>}
{this.state.validityState.tooLong && <div className={classNames("invalid-feedback")}>{maxLengthMessage || "The field shoud not be longer than " + input.props.maxLength}</div>}
{this.state.validityState.rangeOverflow && <div className={classNames("invalid-feedback")}>{maxLengthMessage || "There are too many items. Maximum allowed: " + input.props.max}</div>}
{this.state.validityState.rangeUnderflow && <div className={classNames("invalid-feedback")}>{minValueMessage || "There are too less items. Minimum needed: " + input.props.min}</div>}
</div>
</Col>
</FormGroup>
);
}
private handleInvalid = (ev: React.FormEvent<HTMLInputElement>): any => {
const input = ev.target as HTMLInputElement;
this.setState({ validityState: input.validity });
}
private handleChange = (ev: React.FormEvent<HTMLInputElement>): any => {
const input = ev.target as HTMLInputElement;
this.setState({ validityState: input.validity });
}
}
最佳答案
也许可以让它更简单并删除 refs 和 eventHandling 样板。
您的业务逻辑依赖于 this.state.users.length
,对吗?
所以用它对你有利:
handleUserSelected = (selectedElement: IUser) : void => {
this.setState({
users: [
...this.state.users,
selectedElement,
],
})
}
render() {
const { users } = this.state
const isInvalid = users.length < 3 || users.length > 6
return (
<form>
{isInvalid && <span>Your invalid message</span>}
<UserSearch ... />
</form>
)
}
关于javascript - 触发 react 组件内的更改事件不起作用,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/46400808/