如何从Angular 6中的另一个模块导入服务

技术：使用angular 6、angular cli和typescript

场景：

我有一个应用程序模块和一个核心模块

我希望我的应用程序模块组件使用我的核心模块中的服务

我的核心模块包含一个服务列表：

import { NgModule } from '@angular/core';

// Services
import { AuthService } from './services/auth.service';

@NgModule({
  declarations: [
  ],
  imports: [
  ],
  providers: [
    AuthService
  ]
})
export class CoreModule { }

import { BrowserModule } from '@angular/platform-browser';
import { CommonModule } from '@angular/common';
import { HTTP_INTERCEPTORS, HttpClientModule } from '@angular/common/http';
import { NgModule } from '@angular/core';
import { ReactiveFormsModule, FormsModule } from '@angular/forms';
import { RouterModule } from '@angular/router';

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

// Modules
import { CoreModule } from './core/core.module';

// Sections
import { COMPONENTS } from './components/index';
import { ROUTES } from './app.routes';

@NgModule({
  declarations: [
    AppComponent,
    COMPONENTS
  imports: [
    CommonModule,
    FormsModule,
    BrowserModule,
    HttpClientModule,
    ReactiveFormsModule,
    RouterModule.forRoot(ROUTES),
    CoreModule
  ],
  providers: [
  ],
  bootstrap: [ AppComponent ]
})
export class AppModule { }

import { Component } from '@angular/core';

// This Auth Service import not working (says service not exported)
import { AuthService } from '../../core/core.module';

@Component({
  selector: 'app-contact',
  templateUrl: './contact.component.html'
})
export class ContactComponent {

  constructor(
    private authService: AuthService
  ) {}
}

这是我的应用程序模块：

import { NgModule } from '@angular/core';

// Services
import { AuthService } from './services/auth.service';

@NgModule({
  declarations: [
  ],
  imports: [
  ],
  providers: [
    AuthService
  ]
})
export class CoreModule { }

import { BrowserModule } from '@angular/platform-browser';
import { CommonModule } from '@angular/common';
import { HTTP_INTERCEPTORS, HttpClientModule } from '@angular/common/http';
import { NgModule } from '@angular/core';
import { ReactiveFormsModule, FormsModule } from '@angular/forms';
import { RouterModule } from '@angular/router';

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

// Modules
import { CoreModule } from './core/core.module';

// Sections
import { COMPONENTS } from './components/index';
import { ROUTES } from './app.routes';

@NgModule({
  declarations: [
    AppComponent,
    COMPONENTS
  imports: [
    CommonModule,
    FormsModule,
    BrowserModule,
    HttpClientModule,
    ReactiveFormsModule,
    RouterModule.forRoot(ROUTES),
    CoreModule
  ],
  providers: [
  ],
  bootstrap: [ AppComponent ]
})
export class AppModule { }

import { Component } from '@angular/core';

// This Auth Service import not working (says service not exported)
import { AuthService } from '../../core/core.module';

@Component({
  selector: 'app-contact',
  templateUrl: './contact.component.html'
})
export class ContactComponent {

  constructor(
    private authService: AuthService
  ) {}
}

注意：如您所见，我正在导入CoreModule

这是应用程序模块中的我的组件（它调用核心模块以获取AuthService）：

import { NgModule } from '@angular/core';

// Services
import { AuthService } from './services/auth.service';

@NgModule({
  declarations: [
  ],
  imports: [
  ],
  providers: [
    AuthService
  ]
})
export class CoreModule { }

import { BrowserModule } from '@angular/platform-browser';
import { CommonModule } from '@angular/common';
import { HTTP_INTERCEPTORS, HttpClientModule } from '@angular/common/http';
import { NgModule } from '@angular/core';
import { ReactiveFormsModule, FormsModule } from '@angular/forms';
import { RouterModule } from '@angular/router';

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

// Modules
import { CoreModule } from './core/core.module';

// Sections
import { COMPONENTS } from './components/index';
import { ROUTES } from './app.routes';

@NgModule({
  declarations: [
    AppComponent,
    COMPONENTS
  imports: [
    CommonModule,
    FormsModule,
    BrowserModule,
    HttpClientModule,
    ReactiveFormsModule,
    RouterModule.forRoot(ROUTES),
    CoreModule
  ],
  providers: [
  ],
  bootstrap: [ AppComponent ]
})
export class AppModule { }

import { Component } from '@angular/core';

// This Auth Service import not working (says service not exported)
import { AuthService } from '../../core/core.module';

@Component({
  selector: 'app-contact',
  templateUrl: './contact.component.html'
})
export class ContactComponent {

  constructor(
    private authService: AuthService
  ) {}
}

问题：我正在尝试将一项服务导入我的应用程序模块组件，名为contact component，如下所示：

import { AuthService } from '../../core/core.module';

我得到的错误：

import { NgModule } from '@angular/core';

// Services
import { AuthService } from './services/auth.service';

@NgModule({
  declarations: [
  ],
  imports: [
  ],
  providers: [
    AuthService
  ]
})
export class CoreModule { }

import { BrowserModule } from '@angular/platform-browser';
import { CommonModule } from '@angular/common';
import { HTTP_INTERCEPTORS, HttpClientModule } from '@angular/common/http';
import { NgModule } from '@angular/core';
import { ReactiveFormsModule, FormsModule } from '@angular/forms';
import { RouterModule } from '@angular/router';

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

// Modules
import { CoreModule } from './core/core.module';

// Sections
import { COMPONENTS } from './components/index';
import { ROUTES } from './app.routes';

@NgModule({
  declarations: [
    AppComponent,
    COMPONENTS
  imports: [
    CommonModule,
    FormsModule,
    BrowserModule,
    HttpClientModule,
    ReactiveFormsModule,
    RouterModule.forRoot(ROUTES),
    CoreModule
  ],
  providers: [
  ],
  bootstrap: [ AppComponent ]
})
export class AppModule { }

import { Component } from '@angular/core';

// This Auth Service import not working (says service not exported)
import { AuthService } from '../../core/core.module';

@Component({
  selector: 'app-contact',
  templateUrl: './contact.component.html'
})
export class ContactComponent {

  constructor(
    private authService: AuthService
  ) {}
}

服务不是核心模块的导出成员

---

结果：我希望我的联系人组件从app module导入名为AuthService的核心模块服务。

因为您在

AppModule

中导入了

CoreModule

，在那里您还贴花了

ContactComponent

（似乎在

组件中），服务和组件都属于相同的模块，因此它们可以相互看到。在您的
ContactComponent
中需要做的只是从实际位置导入服务
AuthService
（而不是
。/../core/core.module
）

import { AuthService } from ' <...>/auth.service';

从'/auth.service'导入{AuthService}；
如果在根模块中正确导入模块，我认为如果您将“导出…从…”添加到mymodule.module.ts中：

import { MystuffService } from file 'mystuff.service'. 
export { MystuffService } from file 'mystuff.service'.

然后，您可以导入您的服务：

import { MystuffService } from 'mymodule.module'

你不应该导出服务？@DeborahK为什么？你不应该或者你不能？你不需要。请参见此处的核心模块示例：请注意，它只导出组件，而不导出服务。@DeborahK，这是angular的默认行为还是最近更改的行为？真的非常感谢你的提示。@AngularM正确。实际上再也没有必要使用核心模块了，尤其是在
可注入的
装饰器（v6中新增）的
属性中提供了新的
。根本不需要在模块中注册服务。是的，样式指南需要更新。你的服务是什么样子的？（只是声明）你能回购吗？这是一次小规模的测试？