Angular2将[(ngModel)]与[ngModelOptions] =“" {standalone:true}“一起使用;链接到对模型属性的引用 [英] Angular2 use [(ngModel)] with [ngModelOptions]="{standalone: true}" to link to a reference to model's property
问题描述
假设我有一个Mailtype类型的打字稿对象,如下所示:
Let's say I have a typescript object of type Mailtype like following:
export class Mailtype {
constructor(
public name?: string,
public locale?: string,
public email?: string,
public properties? : Property[]
) { }
}
其中属性"字段是属性类型的数组:
Where its "properties" field is an array of type Property:
export class Property {
constructor(
public name?: string,
public type?: string,
public example?: string,
public required?: boolean,
public masked?: boolean
) { }
}
现在在我的组件中,我有一个Mailtype对象,而html中有一个form元素,用于编辑和添加到Mailtype的属性数组中:
Now in my component I have a single Mailtype object and the html has a form element used for editing and adding to the properties array of the Mailtype:
<form>
<tr *ngFor="let property of model.properties; let i=index">
<td>
<input type="text" [(ngModel)]="property.name" required>
</td>
</tr>
<button (click)="onAddProperty()">Add property</button>
</form>
组件:
export class MailtypeComponent {
model : Mailtype;
constructor() {
this.model = new Mailtype('','','',[]);
this.model.properties.push(new Property());
}
onAddProperty() {
this.model.properties.push(new Property());
}
}
我想知道是否不允许使用[[ngModel)]链接到对数组中数组元素的引用属性",尤其是在我同时迭代数组的同时?因为上面的代码会引发以下错误:
I was wondering if I'm not allowed to use [(ngModel)] to link to a reference "property" to the array element in the array, especially at the same time I'm iterating the array? Because it throws the following error for the above code:
ORIGINAL EXCEPTION: If ngModel is used within a form tag, either the name attribute must be set
or the form control must be defined as 'standalone' in ngModelOptions.
Example 1: <input [(ngModel)]="person.firstName" name="first">
Example 2: <input [(ngModel)]="person.firstName" [ngModelOptions]="{standalone: true}">
因此建议我使用[ngModelOptions]="{standalone: true}"
或将名称字段添加到html中.看起来[ngModelOptions]="{standalone: true}"
在这种情况下可以工作.为什么standalone: true
实际上意味着什么,因为我找不到有关它的任何文档?
So it's suggesting I use either [ngModelOptions]="{standalone: true}"
or add a name field to the html. And it looks like [ngModelOptions]="{standalone: true}"
works in this case. Why does standalone: true
actually means since I cannot find any documentation about it?
推荐答案
在使用<form>
标记时使用@angular/forms
会自动创建FormGroup
.
Using @angular/forms
when you use a <form>
tag it automatically creates a FormGroup
.
对于每个包含ngModel
标签的<input>
,它将创建一个FormControl
并将其添加到上面创建的FormGroup
中;该FormControl
将使用属性name
命名为FormGroup
.
For every contained ngModel
tagged <input>
it will create a FormControl
and add it into the FormGroup
created above; this FormControl
will be named into the FormGroup
using attribute name
.
示例:
<form #f="ngForm">
<input type="text" [(ngModel)]="firstFieldVariable" name="firstField">
<span>{{ f.controls['firstField']?.value }}</span>
</form>
表示这一点,然后回答您的问题.
Said this, the answer to your question follows.
将其标记为standalone: true
时不会发生(不会添加到FormGroup
中).
When you mark it as standalone: true
this will not happen (it will not be added to the FormGroup
).
参考: https://github.com/angular/angular/issues/9230#issuecomment-228116474
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