角度模板验证表格

Question

我正在进行表单验证。我正在使用模板驱动的验证表，其编码如下。它现在可以正常工作，但是当我尝试#username = "ngModel" and #password = "ngModel在输入中添加“以创建验证类时，这向我显示了错误。请也查找错误。

<div class="container">
  <div class="row">
    <div class="centering text-center">
      <div class="login-cont col-md-4 col-md-offset-4 vcenter">
        <form id="login_form" name="login-form" #f="ngForm"  role="form" (ngSubmit)="f.form.valid && login()" novalidate>

          <input id="username" [(ngModel)]="username"  name="username"  required  class="form-control"  type="text"   placeholder="Username" >
<input id="userPassword" class="form-control"  required type="password" name="userPassword" required placeholder="Password" [(ngModel)]="password" >
<button type="submit" class="btn login-btn">Login</button>
</form>
</div>
</div>
</div>
</div>

---

 Cannot assign to a reference or variable!
    at _AstToIrVisitor.visitPropertyWrite (webpack-internal:///../../../compiler/esm5/compiler.js:26226:23)
    at PropertyWrite.visit (webpack-internal:///../../../compiler/esm5/compiler.js:4803:24)
    at convertActionBinding (webpack-internal:///../../../compiler/esm5/compiler.js:25676:45)
    at eval (webpack-internal:///../../../compiler/esm5/compiler.js:28166:22)
    at Array.forEach (<anonymous>)
    at ViewBuilder._createElementHandleEventFn (webpack-internal:///../../../compiler/esm5/compiler.js:28162:18)
    at nodes.(anonymous function) (webpack-internal:///../../../compiler/esm5/compiler.js:27581:27)
    at eval (webpack-internal:///../../../compiler/esm5/compiler.js:28107:22)
    at Array.map (<anonymous>)
    at ViewBuilder._createNodeExpressions (webpack-internal:///../../../compiler/esm5/compiler.js:28106:56)

---

这是我尝试过的，但给我一个错误

   <input id="username" class="form-control"  type="text" required  name="username" placeholder="Username" [(ngModel)]="username" minlength="4"  #names="ngModel">


          <div *ngIf="names.invalid && (names.dirty || names.touched)"
               class="alert alert-danger">
          </div>
            <div *ngIf="names.errors.required">
              Name is required.
            </div>

            <div *ngIf="names.errors.minlength">
              Name must be at least 4 characters long.
            </div>

Answer 1

您因自己variable name和local variable name 彼此相同而出错

username是要分配给的变量，[(ngModel)]='username'与此同时，您还尝试使局部变量#username

使用诸如#username2或的其他名称#password2，将解决您的问题。

有关更多详细信息，请阅读：

https://scotch.io/tutorials/using-angular-2s-template-driven-forms