[英]How to use required validation on <input type=“file”> in angular 4
文字输入正常。 我使用相同的文件,但无法正常工作。
<input type="text" name="title" #title="ngModel" ngModel required class="form-control" placeholder="Title Here">
<div *ngIf="title.errors && (title.dirty || title.touched)">
<span class="help-block error" [hidden]="!title.errors.required"> Title
is Required
</span>
</div>
<input type="file" #image="ngModel" (change)="fileEvent($event)"
name="image" ngModel>
如果您只想显示/隐藏错误消息,则取决于所选文件
@Component({
selector: 'my-app',
template: `
<div>
<input type="file" (change)="onChange($event)" name="image">
<div *ngIf="!fileSelected">
<span class="help-block error" [hidden]="!fileSelected">
File is Required
</span>
</div>
</div>
`,
})
export class AppComponent {
onChange(event) {
var files = event.srcElement.files;
console.log(files);
this.fileSelected = files.length>0;
}
}
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