问题描述
我创建了代表密码表单控件的自定义组件(以下代码已简化).
密码组件 (html)
...<input formControlName="password" type="password"></表单>
密码组件 (ts)
...@成分({选择器:'密码',templateUrl: './password.component.html',styleUrls: ['./password.component.css'],提供者:[{提供:NG_VALUE_ACCESSOR,useExisting: forwardRef(() => PasswordComponent),多:真}]})导出类 PasswordComponent 实现 ControlValueAccessor {密码表格:表格组;onChange =(密码:字符串)=>{ };onTouched = () =>{ };构造函数(){this.passwordForm = new FormGroup({...密码:new FormControl('')});this.passwordForm.valueChanges.subscribe(data => this.onChange(this.value));}获取值():字符串{返回 this.passwordForm.get('password').value;}写值(密码:字符串):无效{this.passwordForm.get('password').setValue(password);this.onChange(this.value);}registerOnChange(fn: any): void { this.onChange = fn;}registerOnTouched(fn: any): void { this.onTouched = fn;}setDisabledState?(isDisabled: boolean): void { }}我在其他组件中使用它而不是标准输入元素:
...<password formControlName="password"></password></表单>
验证器来自外部形式(它们未在 PasswordComponent 中定义)
this.userForm = fb.group({...密码:['', [Validators.minLength(10), Validators.maxLength(100)]]});
我的问题是:如何从 PasswordComponent 内部获取 元素的有效性?我想根据有效性对其进行风格化.换句话说,我如何从代表此控件的 PasswordComponent 中获取 userForm 的密码"控件的有效性.
由于我们无法直接从 DI 系统获取 NgControl
实例,因为我们会收到循环依赖错误.下图显示了如果我们在自定义值访问器中注入 NgControl
会发生这种情况的原因:
现在应该清楚我们有 NgControl ->表单控件名称 ->值访问器 ->CustomValueAccessor ->NgControl
循环依赖
要解决这个问题,您可以利用Injector
来实现:
component.ts
import { NgControl } from '@angular/forms';导出类 PasswordComponent 实现 ControlValueAccessor {...ngControl: ngControl;构造函数(私有注入:注入器){...}ngOnInit() {this.ngControl = this.inj.get(NgControl)}
template.html
{{ ngControl.control.valid }}
I created custom component representing password form control (code below is simplified).
PasswordComponent (html)
<form [formGroup]="passwordForm">
...
<input formControlName="password" type="password">
</form>
PasswordComponent (ts)
...
@Component({
selector: 'password',
templateUrl: './password.component.html',
styleUrls: ['./password.component.css'],
providers: [{
provide: NG_VALUE_ACCESSOR,
useExisting: forwardRef(() => PasswordComponent),
multi: true
}]
})
export class PasswordComponent implements ControlValueAccessor {
passwordForm: FormGroup;
onChange = (password: string) => { };
onTouched = () => { };
constructor() {
this.passwordForm = new FormGroup({
...
password: new FormControl('')
});
this.passwordForm.valueChanges.subscribe(data => this.onChange(this.value));
}
get value(): string {
return this.passwordForm.get('password').value;
}
writeValue(password: string): void {
this.passwordForm.get('password').setValue(password);
this.onChange(this.value);
}
registerOnChange(fn: any): void { this.onChange = fn; }
registerOnTouched(fn: any): void { this.onTouched = fn; }
setDisabledState?(isDisabled: boolean): void { }
}
I use it in other components instead of standard input element:
<form [formGroup]="userForm">
...
<password formControlName="password"></password>
</form>
Validators are coming from outer form (they're not defined inside PasswordComponent)
this.userForm = fb.group({
...
password: ['', [Validators.minLength(10), Validators.maxLength(100)]]
});
My question is: how can I get <password>
element validity from inside PasswordComponent? I would like to stylize it based on validity. In other words how can I get validity of userForm's 'password' control from PasswordComponent that represents this control.
As we can't get NgControl
instance directly from DI system since we'll get a circular dependency error. The following diagram shows why it happens if we inject NgControl
in our custom value accessor:
Now it should be clear that we have NgControl -> FormControlName -> ValueAccessor -> CustomValueAccessor -> NgControl
circular dependency
To work around it you can leverageInjector
to achieve that:
component.ts
import { NgControl } from '@angular/forms';
export class PasswordComponent implements ControlValueAccessor {
...
ngControl: NgControl;
constructor(private inj: Injector) {
...
}
ngOnInit() {
this.ngControl = this.inj.get(NgControl)
}
template.html
{{ ngControl.control.valid }}
这篇关于访问自定义表单控件的有效值的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!