我有这个输入：
<form #f="ngForm" name="productForm">
<md-input [(ngModel)]="product.price" name="price" required="true" placeholder="Price (USD)"></md-input>
<div ng-messages="productForm.price.$error" role="alert">
<div ng-message-exp="['required']">
Price is required
</div>
</div>
</form>
但是需要消息价格不会出现.
我该如何正确格式化错误消息？
当价格输入为空时,将显示ng-invalid类：
我想要的是具有类似于angular1 md design的样式,如下所示：
希望这将添加为angular2-material演变,但目前模仿这种方法的方法是设置dividerColor并使用MD-HINT指令.例：
<md-input placeholder="Email address"
#email="ngModel"
name="email"
type="text"
fullWidth={true}
[(ngModel)]="model.email"
required
email
dividerColor="{{ !email.valid ? 'warn' : 'primary' }}">
<md-hint [hidden]="email.pristine || email.valid">
<span [hidden]="email.errors?.required || !email.errors?.email">
This doesn't appear to be a valid email address.
</span>
<span [hidden]="!email.errors?.required">Email address is required.</span>
</md-hint>
</md-input>
