Write a complete Angular4 FormText component method
This article mainly introduces how to write a complete Angular4 FormText component. The editor thinks it is quite good, so I will share it with you now and give it as a reference. Let’s follow the editor to take a look, I hope it can help everyone.
Component definition
import { Component, Output, Input, forwardRef, EventEmitter} from '@angular/core';
import {ControlValueAccessor, NG_VALUE_ACCESSOR} from '@angular/forms';
@Component({
selector: 'form-text',
template: `
<p >
<label>{{label}}：</label>
<input type="text" [(ngModel)]="value"
placeholder="{{placeholder}}" >
</p>
`,
providers: [
{
provide:NG_VALUE_ACCESSOR,
useExisting:forwardRef(()=>FormTextComponent),
multi:true
}
]
})
export class FormTextComponent implements ControlValueAccessor {
@Input() label:string = '';
@Input() placeholder: string='';
@Output() onChange: EventEmitter<any> = new EventEmitter<any>();
public innerValue: any;
public changeFn: Function = () => {};
get value(): any {
return this.innerValue;
};
set value(v: any) {
if (v !== this.innerValue) {
this.innerValue = v;
this.changeFn(v);
}
}
writeValue(value: any) {
if (value !== this.innerValue) {
this.innerValue = value;
}
}
registerOnChange(fn: any) {
this.changeFn = fn;
}
registerOnTouched(fn: any) {
//
}
}Component usage
<form-text [(ngModel)]="mobile" [placeholder]="placeholder" [label]="label"></form-text>
<p>{{mobile}}</p>Requires attention Points:
1. Need to configure the providers of the component
2. Need to implement the ControlValueAccessor interface
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