[英]Disable selected option of the first select box in the second select box
[英]Select box not showing the selected option first
我正在使用角度6,但無法在選擇框中將所選選項顯示為默認選項,
HTML組成
<select class="form-control selectBox" name="username" #username="ngModel" required ngModel>
<option disabled selected>Select User Name</option>
<option *ngFor="let user of userList" [value]="user.uid">{{user.name }}</option>
</select>
TS:
import { Component } from '@angular/core';
@Component({
selector: 'my-app',
templateUrl: './app.component.html',
styleUrls: [ './app.component.css' ]
})
export class AppComponent {
name = 'Angular';
userList: any = [
{
"name" : "Test User"
},
{
"name" : "Hello World"
},
{
"name" : "User Three"
}
]
}
它在選擇框中顯示默認的空值。
如何在行中的選擇框中顯示所選選項的默認設置?
<option disabled selected>Select User Name</option>
Stackblitz: https ://stackblitz.com/edit/angular-wfjmlm
您需要在選擇框中設置一個值,如下所示:
<option disabled selected value="">Select User Name</option>
將使其工作。
加[value]=""
<option disabled [value]="" selected>Select User Name</option>
如果要隱藏禁用選項,則添加hidden
屬性
<option hidden disabled [value]="" selected>Select User Name</option>
我幾乎建議使用ReactiveForms。 這樣,您將獲得更簡潔的代碼以及更強大的選項。
首先將ReactiveForms導入到您的app.module
:
import {FormsModule, ReactiveFormsModule} from '@angular/forms';
...
imports: [
...
ReactiveFormsModule
...
]
然后在您的控制器中:
myForm: FormGroup;
constructor(private fb: FormBuilder){
this.myForm = this.fb.group({
username: null
})
}
在您的模板中:
<form [formGroup]="myForm">
<select formControlName="username" placeholder="Select Username">
<option disabled selected>Select User Name</option>
<option *ngFor="let user of userList" [value]="user.uid">{{user.name }}</option>
</select>
該解決方案可以在以下找到,如下是html
<select class="form-control selectBox" name="username" [(ngModel)]="selected" required>
<option disabled selected>Select User Name</option>
<option *ngFor="let user of userList" >{{user.name }}</option>
</select>
<hr> {{selected}}
以下是控制器
import { Component } from '@angular/core';
@Component({
selector: 'my-app',
templateUrl: './app.component.html',
styleUrls: ['./app.component.css']
})
export class AppComponent {
name = 'Angular';
userList: any = [
{
"name": "Test User"
},
{
"name": "Hello World"
},
{
"name": "User Three"
}
];
selected = 'Select User Name';
}
使用棱角材質而不是select和option。 例如:
<mat-form-field>
<mat-select placeholder="Select User Name">
<mat-option *ngFor="let user of userList" [value]="user.uid">
{{food.viewValue}}
</mat-option>
</mat-select>
</mat-form-field>
此處有更多詳細信息: https : //material.angular.io/components/select/overview
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