javascript - "Can' t 绑定(bind)到 'ngModel' 因为它是 't a known property of ' p-calendar '"尝试使用 PrimeNG 组件的错误消息，为什么？

Question

我是 Angular 2\4 的新手，我正在尝试按照这个快速视频教程将 PrimeNG 组件添加到我的 Angular 项目中:

https://www.youtube.com/watch?v=6Nvze0dhzkE

和 PrimeNG 教程页面的入门部分:https://www.primefaces.org/primeng/#/setup

所以这是我的 app.component.html View :

<!--The whole content below can be removed with the new code.-->
<div style="text-align:center">
  <h1>
    Welcome to {{title}}!!
  </h1>
</div>

<p-calendar [(ngModel)]="value"></p-calendar>

{{value | date:'dd.mm.yyy'}}

如您所见，我插入了这个标签来显示日历组件:

<p-calendar [(ngModel)]="value"></p-calendar>

(如该组件的官方文档所示:https://www.primefaces.org/primeng/#/calendar)

这里我遇到了第一个问题，因为 IntelliJ 给我这个错误信息:

Error:(9, 13) Angular: Can't bind to 'ngModel' since it isn't a known property of 'p-calendar'.
1. If 'p-calendar' is an Angular component and it has 'ngModel' input, then verify that it is part of this module.
2. If 'p-calendar' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.
3. To allow any property add 'NO_ERRORS_SCHEMA' to the '@NgModule.schemas' of this component.

我认为这很奇怪，因为这一行应该将用户在日历上选择的值绑定(bind)到我模型的 value 变量。

按照教程，我以这种方式修改了 app.module.ts 文件:

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';

import { AppComponent } from './app.component';
import {CalendarModule} from 'primeng/primeng';


@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    CalendarModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

export class MyModel {
  value: Date;
}

正如你在这里看到的，我已经导出了这个类:

export class MyModel {
  value: Date;
}

具有 value 属性(类型为 Date)，因此它应该是 View 中此行绑定(bind)的属性:

<p-calendar [(ngModel)]="value"></p-calendar>

但它无法工作，当我在 JavaScript 浏览器控制台中访问此应用程序时，我收到此错误消息:

compiler.es5.js:1690 Uncaught Error: Template parse errors:
Can't bind to 'ngModel' since it isn't a known property of 'p-calendar'.
1. If 'p-calendar' is an Angular component and it has 'ngModel' input, then verify that it is part of this module.
2. If 'p-calendar' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule.schemas' of this component to suppress this message.
3. To allow any property add 'NO_ERRORS_SCHEMA' to the '@NgModule.schemas' of this component. ("<p-calendar [ERROR ->][(ngModel)]="value"></p-calendar {{value | date:'dd.mm.yyy'}}
"): ng:///AppModule/AppComponent.html@8:12
    at syntaxError (http://localhost:4200/vendor.bundle.js:7283:34)
    at TemplateParser.webpackJsonp../node_modules/@angular/compiler/@angular/compiler.es5.js.TemplateParser.parse (http://localhost:4200/vendor.bundle.js:18403:19)
    at JitCompiler.webpackJsonp../node_modules/@angular/compiler/@angular/compiler.es5.js.JitCompiler._compileTemplate (http://localhost:4200/vendor.bundle.js:32555:39)
    at http://localhost:4200/vendor.bundle.js:32475:62
    at Set.forEach (native)
    at JitCompiler.webpackJsonp../node_modules/@angular/compiler/@angular/compiler.es5.js.JitCompiler._compileComponents (http://localhost:4200/vendor.bundle.js:32475:19)
    at http://localhost:4200/vendor.bundle.js:32362:19
    at Object.then (http://localhost:4200/vendor.bundle.js:7272:148)
    at JitCompiler.webpackJsonp../node_modules/@angular/compiler/@angular/compiler.es5.js.JitCompiler._compileModuleAndComponents (http://localhost:4200/vendor.bundle.js:32361:26)
    at JitCompiler.webpackJsonp../node_modules/@angular/compiler/@angular/compiler.es5.js.JitCompiler.compileModuleAsync (http://localhost:4200/vendor.bundle.js:32290:37)
syntaxError @   compiler.es5.js:1690
webpackJsonp../node_modules/@angular/compiler/@angular/compiler.es5.js.TemplateParser.parse @   compiler.es5.js:12810
webpackJsonp../node_modules/@angular/compiler/@angular/compiler.es5.js.JitCompiler._compileTemplate @   compiler.es5.js:26962
(anonymous) @   compiler.es5.js:26882
webpackJsonp../node_modules/@angular/compiler/@angular/compiler.es5.js.JitCompiler._compileComponents   @   compiler.es5.js:26882
(anonymous) @   compiler.es5.js:26769
then    @   compiler.es5.js:1679
webpackJsonp../node_modules/@angular/compiler/@angular/compiler.es5.js.JitCompiler._compileModuleAndComponents  @   compiler.es5.js:26768
webpackJsonp../node_modules/@angular/compiler/@angular/compiler.es5.js.JitCompiler.compileModuleAsync   @   compiler.es5.js:26697
webpackJsonp../node_modules/@angular/core/@angular/core.es5.js.PlatformRef_._bootstrapModuleWithZone    @   core.es5.js:4536
webpackJsonp../node_modules/@angular/core/@angular/core.es5.js.PlatformRef_.bootstrapModule @   core.es5.js:4522
./src/main.ts   @   main.ts:11
__webpack_require__ @   bootstrap a55b161…:54
2   @   main.ts:11
__webpack_require__ @   bootstrap a55b161…:54
webpackJsonpCallback    @   bootstrap a55b161…:25
(anonymous)

为什么？怎么了？我错过了什么？我该如何尝试解决这个问题？在我看来，我遵循了教程......

Answer 1

在您的 AppModule 中添加 FormsModule:

// ...
import { FormsModule } from '@angular/forms';
// ...

@NgModule({
  // ...
  imports: [
    BrowserModule,
    FormsModule,
    CalendarModule
  ],
  // ...
})
export class AppModule { }