无法绑定到 'formGroup'，因为它不是 Angular 中 'form' 的已知属性 8

Question

无法解决无法绑定到 formGroup 因为它不是已知的属性表单。

我已经尝试了所有的解决方案已经添加 ReactiveFormsModule , FormsModule 还尝试了 [formGroup] 和 [FormGroup] 仍然得到相同的错误

import { ReactiveFormsModule , FormsModule } from '@angular/forms';

 imports: [
    BrowserModule,
    FormsModule,
    ReactiveFormsModule,
  ]

我的表格

<form [formGroup]="addPostForm" (ngSubmit)="addNewPost()">
     <ion-item>
          <ion-label class="grey" position="stacked">Caption </ion-label>
          <ion-input type="text" formControlName="caption"></ion-input>
     </ion-item>
     <ion-button expand="block" type="submit" shape="round">Save</ion-button>
</form>

添加-post.page.ts

import { Component, OnInit } from '@angular/core';
import { IonSlides } from '@ionic/angular';
import { ApiService } from '../services/api.service';
import { Router } from "@angular/router"
import { FormBuilder, FormGroup, Validators, ReactiveFormsModule, FormsModule } from '@angular/forms';


@Component({
  selector: 'app-add-post',
  templateUrl: './add-post.page.html',
  styleUrls: ['./add-post.page.scss'],
})
export class AddPostPage implements OnInit {

    addPostForm: FormGroup;
    picture = null;
    submitted = false;
    success = false;

    constructor(
        private api: ApiService,
        private FormBuilder: FormBuilder,
        private router: Router,
    ) {
        this.addPostForm = this.FormBuilder.group({
            caption: ['']
        });
    }

Error

Answer 1

在您的 component.ts 文件中（上面的表单代码在 HTML 页面中包含的 component.ts 文件），请启动表单

像这样：

addPostForm: FormGroup = new FormGroup({
  caption: new FormControl('', [Validators.required]) // If validators are required, otherwise you can remove the [Validators.required] part.
});

Answer 2

您需要在 app.component.ts 文件中设置表格。请参考下面的代码，

import { Component } from '@angular/core';
import { AuthenticationService } from './services/authentication.service';
import { Router } from '@angular/router';

import { Platform } from '@ionic/angular';
import { SplashScreen } from '@ionic-native/splash-screen/ngx';
import { StatusBar } from '@ionic-native/status-bar/ngx';
import { FormGroup, FormControl } from '@angular/forms';

@Component({
  selector: 'app-root',
  templateUrl: 'app.component.html',
  styleUrls: ['app.component.scss']
})
export class AppComponent {
  navigate : any;
  //Need to define addPostForm here.
  addPostForm = new FormGroup({
    caption: new FormControl('')
  });
  constructor(
    private platform: Platform,
    private splashScreen: SplashScreen,
    private statusBar: StatusBar,
    private authenticationService: AuthenticationService,
    private router: Router
  ) {
    this.sideMenu();
    this.initializeApp();
  }

有关更多参考，请参阅 this angular 反应形式的文档。

注意：如果你的组件是在另一个模块中导入的，那么在其他模块中你需要在这个模块中导入ReactiveFormsModule。

无法绑定到 'formGroup'，因为它不是 Angular 中 'form' 的已知属性 8

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无法绑定到 'formGroup'，因为它不是 Angular 中 'form' 的已知 属性 8

Can't bind to 'formGroup' since it isn't a known property of 'form' in Angular 8

angular

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ionic4

angular8

无法绑定到 'formGroup'，因为它不是 Angular 中 'form' 的已知属性 8