在 Angular 4 中的多个模块中导入组件

Question

我有一个SharedModule

import { NgModule } from '@angular/core';
import { ControlMessagesComponent } from './control-messages.component';

@NgModule({
  imports: [
  ],
  declarations: [
    ControlMessagesComponent
  ],
  exports: [
    ControlMessagesComponent,
  ]
})

export class SharedModule {}

然后我导入了 2 个不同的模块：

import { SharedModule } from './../shared/shared.module';

@NgModule({
  imports: [
      SharedModule
  ],
  declarations: [
  ],
  providers: [
  ]
})

export class OnboardModule {}

import { SharedModule } from '../shared/shared.module';
@NgModule({
  imports: [
    SharedModule
  ],
  declarations: [

  ],
  providers: [

  ]
})

export class AModule {}

这是ControlMessagesComponent

import { Component, Input } from '@angular/core';
import { FormGroup, FormControl } from '@angular/forms';
import { ValidationService } from './../validators/validator';

@Component({
  selector: 'control-messages',
  template: `<div *ngIf="errorMessage !== null">{{errorMessage}}</div>`
})
export class ControlMessagesComponent {
  @Input() control: FormControl;
  constructor() {}

  get errorMessage() {
    for (const propertyName in this.control.errors) {
      if (this.control.errors.hasOwnProperty(propertyName) && this.control.touched) {
        return ValidationService.getValidatorErrorMessage(propertyName, this.control.errors[propertyName]);
      }
    }
    return null;
  }
}

当我使用它时： <control-messages [control]="form.controls.assetName"></control-messages>

我收到以下错误：

Can't bind to 'ngIf' since it isn't a known property of 'div'. ("]*ngIf="errorMessage !== null">{{errorMessage}}"): ng:///SharedModule/ControlMessagesComponent.html@0:5 Property binding ngIf not used by any directive on an embedded template. Make sure that the property name is spelled correctly and all directives are listed in the "@NgModule.declarations". ("[ERROR ->]{{errorMessage}}"): ng:///SharedModule/ControlMessagesComponent.html@0:0

我别无选择，有人可以告诉我我做错了什么吗？

Answer 1

将 CommonModule 添加到您的 SharedModule。 NgIf 和 NgForOf 也是 CommonModule 中的指令。您的组件实际上在 SharedModule 中，使用 NgIf，因此您必须将其导入到您的模块中。

Description

The module that includes all the basic Angular directives like NgIf, NgForOf,

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { ControlMessagesComponent } from './control-messages.component';

@NgModule({
  imports: [
     CommonModule
  ],
  declarations: [
    ControlMessagesComponent
  ],
  exports: [
    ControlMessagesComponent,
  ]
})

export class SharedModule {}

在 Angular 4 中的多个模块中导入组件

importing a component in multiple module in Angular 4

typescript

angular-module

angular