问题
我正在使用角度5,并构建了具有3个控件的组件
<ss-multiselect-dropdown id="type" formControlName="type" (ngModelChange)="onChange('type')"></ss-multiselect-dropdown>
<input id="caption" type='text' formControlName='caption' (input)="onChange('caption')" />
<custom-uploader formControlName="url" (input)="onChange('url')"></custom-uploader>
从onChange
或ss-multiselect-dropdown
调用input
时
逐步执行onChange
方法时,模型将显示期望值。但是,当onChange
调用custom-uploader
时,旧值(调用onChange
之前的值)仍会应用于模型。
要明确:
“期望值”是指我为该控件选择或输入的值
我尝试更改
<custom-uploader formControlName="url" (input)="onChange('url')"></custom-uploader>
到
<custom-uploader formControlName="url" (change)="onChange('url')"></custom-uploader>
和
<custom-uploader formControlName="url" (ngModelChange)="onChange('url')"></custom-uploader>
似乎onChange
完成后,模型已更新。我做错了什么?
代码
custom-uploader.component.html
<div class="form-group">
<div class="input-group file-upload">
<input type="file" (change)="fileChange(input)" #input class="file-upload-btn"/>
<input type="text" class="form-control" placeholder="Choose a file..." value="{{file}}">
<i class="fa fa-times delete-file" (click)="removeFile()" *ngIf="file"></i>
<span class="input-group-btn">
<button class="btn btn-primary" type="button"><i class="fa fa-upload"></i></button>
</span>
</div>
</div>
custom-uploader.component.ts
import { Component, ViewEncapsulation, ChangeDetectorRef, ViewChild, Output, EventEmitter, forwardRef, SimpleChanges, OnChanges } from '@angular/core';
import { NG_VALUE_ACCESSOR, ControlValueAccessor, NG_VALIDATORS } from '@angular/forms';
import { Ng2ImgMaxService } from 'ng2-img-max';
@Component({
selector: 'custom-uploader',
encapsulation: ViewEncapsulation.None,
templateUrl: './file-uploader.component.html',
styleUrls: ['./file-uploader.component.scss'],
providers: [
{ provide: NG_VALUE_ACCESSOR, useExisting: forwardRef(() => FileUploaderComponent), multi: true }
]
})
export class FileUploaderComponent implements OnChanges, ControlValueAccessor {
@ViewChild('input') fileUploaderInput: any;
public file:any;
public propagateChange = (_: any) => {};
constructor(
private _changeDetectorRef: ChangeDetectorRef,
private _ng2ImgMaxService: Ng2ImgMaxService
) { }
writeValue(obj: any): void
{
this.file = obj;
this._changeDetectorRef.detectChanges();
}
registerOnChange(fn: any): void {
this.propagateChange = fn;
}
registerOnTouched(fn: any): void { }
setDisabledState?(isDisabled: boolean): void { }
ngOnChanges(changes: SimpleChanges): void { }
fileChange(input){
const reader = new FileReader();
if (input.files.length) {
this.file = input.files[0].name;
this.propagateChange(this.file);
this.fileUploaderInput.nativeElement.value = "";
}
}
removeFile():void{
this.file = '';
this.propagateChange(this.file);
}
}
答案 0 :(得分:1)
像(change)
这样的括号语法是指EventEmitter
,该FileUploaderComponent
在值更改时会发出事件。您必须像这样在@Output() change = new EventEmitter<string>();
...
fileChange(input){
const reader = new FileReader();
if (input.files.length) {
this.file = input.files[0].name;
this.change.next(this.file);
...
}
}
中自己实现它:
<custom-uploader formControlName="url" (change)="onChange($event)"></custom-uploader>
然后实例化它:
模板:
onChange(fileName: string) {
//Whatever you want to do with the fileName
}
TypeScript:
s.ios.deployment_target = '9.0'
s.pod_target_xcconfig = { 'SWIFT_VERSION' => '4.1' }
s.source_files = 'CustomPod/Classes/*.swift'
s.resources = 'CustomPod/Frameworks/Privateframework.bundle'
s.vendored_frameworks = 'CustomPod/Frameworks/Privateframework. framework'
s.xcconfig = { 'FRAMEWORK_SEARCH_PATHS' => '$(SYSTEM_LIBRARY_DIR)/CustomPod/Frameworks/' }