角度6：无法绑定到“FormGroup”，因为它不是“Form”的已知属性

Question

我是Angular 6的新手，正在研究ReactiveForms。获取此错误并无法编译。我已经看到了不同的解决方案，并在导入中添加了ReactiveFormsModule指令，就像解决方案中建议的那样，但它仍然显示了相同的错误。请帮忙。

import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { SignupFormComponent } from './signup-form/signup-form.component';
import { AuthorsService } from './authors.service';
import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

@NgModule({
  declarations: [
    AppComponent,
    SignupFormComponent,
    CoursesComponent,
    CourseComponent,
    AuthorsComponent,
    FavoriteComponent,
    TitleCasePipe,
    PanelComponent,
    LikeComponent,
    ZippyComponent,
    ContactFormComponent,
    NewCourseFormComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    ReactiveFormsModule
  ],

import { FormGroup, FormControl, ReactiveFormsModule } from '@angular/forms';
import { Component } from '@angular/core';

@Component({
  selector: 'signup-form',
  templateUrl: './signup-form.component.html',
  styleUrls: ['./signup-form.component.css']
})
export class SignupFormComponent {
  form = new FormGroup({
    username: new FormControl(),
    password: new FormControl()
  });

}

<form [FormGroup]="form">
    <div class="form-group">
        <label for="username">Username</label>
        <input 
            formControlName="username"
            id="username" 
            type="text" 
            class="form-control">
    </div>
    <div class="form-group">
        <label for="password">Password</label>
        <input 
            formControlName="password"
            id="password" 
            type="text" 
            class="form-control">
    </div>
    <button class="btn btn-primary" type="submit">Sign Up</button>
</form>

Answer 1

请在HTML下面使用

<form [formGroup]="form">
...
</form>

因为在[formGroup]中使用了大写字母F,所以出现了错误。