我的表格是按以下方式制作的:
<form #form="ngForm" novalidate (ngSubmit)="register(form);">
<div class="registerinput">
<label for="firstname">First Name</label>
<input #firstname="ngModel" type="text" name="firstname" maxlength="30" pattern="[a-zA-Z ]*" required ngModel>
<div [hidden]="!form.controls.firstname.touched && !form.controls.firstname.errors?.required" class="alert-danger">
Please enter your name
</div>
<div [hidden]="!form.controls.firstname.touched && !form.controls.firstname.errors?.maxlength" class="alert-danger">
Max length is 30 characters
</div>
<div [hidden]="!form.controls.firstname.touched && !form.controls.firstname.errors?.pattern" class="alert-danger">
Only letters are allowed
</div>
</div>
<div class="registerinput">
<button type="submit" class="btn-register">Register</button>
</div>
</form>
我收到以下错误:
EXCEPTION: Uncaught (in promise): Error: Error in http://localhost:3000/app/register/register.component.html:7:17 caused by: Cannot read property 'touched' of undefined
Error: Error in http://localhost:3000/app/register/register.component.html:7:17 caused by: Cannot read property 'touched' of undefined
它似乎找不到我的控件。但是,当我尝试打印 form.controls 时,我得到以下结果:
所以在这种情况下,它发现它们很好。这里有什么问题?我过去做过类似的东西。
更新:我发现我必须使用 firstname.touched
来访问它们,而不是例如 form.controls.firstname.touched
。我只是不明白为什么,因为我在同一个项目中有另一个文件,我在其中使用以完全相同的方式制作的表单,但在那个文件中我使用的是 form.controls.*
。我猜你可以使用 firstname.touched
如果你已经声明了一个模板引用变量,但我不知道在什么情况下你可以使用 form.controls.*
.
最佳答案
另一种验证方式是:
<form #form="ngForm" novalidate (ngSubmit)="register(form);">
<div class="registerinput">
<label for="firstname">First Name</label>
<input #firstname="ngModel" type="text" name="firstname" maxlength="30" pattern="[a-zA-Z ]*" required ngModel>
<div [hidden]="!firstname.touched && !firstname.errors?.required" class="alert-danger">
Please enter your name
</div>
<div [hidden]="!firstname.touched && !firstname.errors?.maxlength" class="alert-danger">
Max length is 30 characters
</div>
<div [hidden]="!firstname.touched && !firstname.errors?.pattern" class="alert-danger">
Only letters are allowed
</div>
</div>
<div class="registerinput">
<button type="submit" class="btn-register" [disabled]='!form.valid'>Register</button>
</div>
</form>
这是一种非常简单易行的方法。
关于forms - 表单控件未定义,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/43121074/