角MatFormControl,ControlValueAccessor [英] Angular MatFormControl, ControlValueAccessor
问题描述
我有一个自定义组件,它是mat-select的包装. 如何在其他组件中使用它?我当时在阅读有关formControl和controlValueAccessor的信息,但我不太了解.
I have a custom component, it's a wrap for mat-select. How can I use it in others component's? I was reading about formControl and controlValueAccessor, but I don't understand alot.
我的custom.html
my custom.html
<mat-select>
<mat-option [value]="opt" *ngFor="let op of opt; index as i">{{opt[i]}}</mat-option>
</mat-select>
<input matInput>
我的custom.ts
my custom.ts
import { Component, OnInit, Input } from '@angular/core';
import { MatFormFieldControl } from '@angular/material/form-field';
@Component({
selector: 'cust-input',
templateUrl: './input.component.html',
styleUrls: ['./input.component.scss'],
providers: [{provide: MatFormFieldControl, useExisting: InputComponent}]
})
export class InputComponent extends MatFormFieldControl<string> implements OnInit {
@Input() opt: string;
setDescribedByIds(ids: string[]): void {
throw new Error('Method not implemented.');
}
onContainerClick(event: MouseEvent): void {
throw new Error('Method not implemented.');
}
constructor() {
super();
}
ngOnInit(): void {
}
}
我的app.html
my app.html
<mat-form-field>
<cust-input [opt]="myopt"></cust-input>
</mat-form-field>
我的app.ts
import { Component } from '@angular/core';
@Component({
selector: 'app-root',
templateUrl: './app.component.html',
styleUrls: ['./app.component.scss']
})
export class AppComponent {
title = 'form';
myopt = ['a', 'b', 'c', 'd'];
}
我不需要像 我的custmo.html
I don't need to something like my custmo.html
<mat-form-field>
<mat-select>
<mat-option [value]="opt" *ngFor="let op of opt; index as i">{{opt[i]}}</mat-option>
</mat-select>
<input matInput>
</mat-form-field>
推荐答案
所以答案是: 如果要使用自定义包装,则需要为其创建一个自定义表格字段控件, 在我们的情况下,我们需要创建自定义的mat-form-field-control
so the answer is: if we want to use our custom wrappe, we need to create a custom form-field-control for it, in our case we need to create custom mat-form-field-control
//我们的自定义表单字段控件
//our custom form field control
import { ValueAccessor } from './value-accessor';
import { MatFormFieldControl } from '@angular/material/form-field';
import {
Input,
HostBinding,
Optional,
Self,
ElementRef,
OnDestroy,
Directive,
} from '@angular/core';
import { FocusMonitor } from '@angular/cdk/a11y';
import { coerceBooleanProperty } from '@angular/cdk/coercion';
import { NgControl } from '@angular/forms';
import { Subject } from 'rxjs';
@Directive()
export class FormControlDirective<T> extends ValueAccessor<T>
implements MatFormFieldControl<T>, OnDestroy {
@Input()
get value() {
return this._value;
}
set value(val: T) {
if (val !== this._value) {
this._value = val;
this.stateChanges.next();
}
}
@Input()
get placeholder() {
return this._placeholder;
}
set placeholder(plc: string) {
this._placeholder = plc;
this.stateChanges.next();
}
@Input()
get required() {
return this._required;
}
set required(req: boolean) {
this._required = coerceBooleanProperty(req);
this.stateChanges.next();
}
get empty() {
return !this._value;
}
constructor(
@Optional() @Self() public ngControl: NgControl,
private fM: FocusMonitor,
private elRef: ElementRef<HTMLElement>
) {
super();
if (this.ngControl != null) {
this.ngControl.valueAccessor = this;
}
fM.monitor(elRef.nativeElement, true).subscribe((origin) => {
this.focused = !!origin;
this.stateChanges.next();
});
}
@HostBinding('class.floating')
get shouldLabelFloat() {
return this.focused || !this.empty;
}
private _value: T | null;
private _placeholder: string;
private _required = false;
nextId = 0;
stateChanges: Subject<void> = new Subject<void>();
focused = false;
@HostBinding() id = `${this.nextId++}`;
errorState = false;
controlType = 'my-select';
autofilled?: boolean;
@HostBinding('attr.aria-desribedby') describedBy = '';
setDescribedByIds(ids: string[]): void {
this.describedBy = ids.join('');
}
onContainerClick(event: MouseEvent): void {
if ((event.target as Element).tagName.toLowerCase() === 'input') {
this.elRef.nativeElement.focus();
}
}
ngOnDestroy(): void {
this.fM.stopMonitoring(this.elRef.nativeElement);
this.stateChanges.complete();
}
}
但是,如果要在包装器中使用ngModel,还需要创建自定义控件值访问器
But, if we want to use ngModel in our wrapper, we also need to create our custom control value accessor
客户价值访问者
import { ControlValueAccessor } from '@angular/forms';
export class ValueAccessor<T> implements ControlValueAccessor {
value: T | null;
onChange: Function;
onTouched: Function;
disabled: boolean;
writeValue(val: T): void {
this.value = val;
}
registerOnChange(fn: Function): void {
this.onChange = fn;
}
registerOnTouched(fn: Function): void {
this.onTouched = fn;
}
setDisabledState?(isDisabled: boolean): void {
this.disabled = isDisabled;
}
}
在我们的custom.wrapper.component.ts中,我们需要扩展表单控件, 另外,查看custom-form-field-control,然后查看consructor,有一个ngControl,我们将其添加到其中,以便一次使用form-control和value-accessor.
In our custom.wrapper.component.ts we need to extand our form-control, also, look in to custom-form-field-control, and look in to consructor, there is a ngControl, we add it there, for using form-control and value-accessor in one time.
select.component.ts
select.component.ts
import { Component, Input, OnInit } from '@angular/core';
import { MatFormFieldControl } from '@angular/material/form-field';
import { FormControlDirective } from 'src/app/forms/form-control';
@Component({
selector: 'app-select',
templateUrl: './select.component.html',
styleUrls: ['./select.component.scss'],
providers: [{ provide: MatFormFieldControl, useExisting: SelectComponent }],
})
export class SelectComponent extends FormControlDirective<string>
implements OnInit {
@Input() option: string;
ngOnInit() {}
}
在wrapper.component.ts中的
中查看提供程序,在那里,我们告诉Native MatFormFieldControl,类似(我有自己的表单控件,让我们使用它). 下一步是创建我们的包装
in wrapper.component.ts take a look into providers, there, we are telling to Native MatFormFieldControl, something like (Hi, I have my own form-control, let's use it). Next step is to create our wrapp
select.component.html
select.component.html
<mat-select [(ngModel)]="value">
<mat-option [value]="item" *ngFor="let item of option; index as j">{{
option[j]
}}</mat-option>
</mat-select>
所以,现在我们可以在mat-form-field内的其他组件中使用它
So, for now we can use it in other coponents, inside mat-form-field
app.component.html
app.component.html
<mat-form-field>
<mat-label>label</mat-label>
<app-select [option]="opt" [(ngModel)]="title"></app-select>
</mat-form-field>
有一些有用的链接:
现在,我又遇到了XD麻烦 我确实需要在中使用ngModel的一些方法,但这是在应用程序选择中&一次选择垫子.找到答案后,请对此进行编辑
And for now, I get another trouble XD Some how I need to use ngModel, exactly in , but It's in the app-select & mat-select at one time. When I finde an answer, I edit this
这篇关于角MatFormControl,ControlValueAccessor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IT屋!