Question

我在使用Angular2 DI时遇到了麻烦。我尝试将一个类注入另一个类，它引发了以下错误：

消息：public function login() { $rules =$this->User_M->_rules; $this->form_validation->set_rules($rules); if($this->form_validation->run()==TRUE) { //we can login and redirect $checkLoggedIn = $this->User_M->login(); if($checkLoggedIn) { $this->data['subview']='admin/user/login'; $this->load->view('admin/_layout_modal',$this->data); } else { echo "Login Failed"; } } }

完整筹码："Cannot resolve all parameters for 'ProductService'(undefined). Make sure that all the parameters are decorated with Inject or have valid type annotations and that 'ProductService' is decorated with Injectable."

这里奇怪的是我得到了两个类，一个被注射，一个接受注射，用"BaseException@http://localhost:5555/node_modules/@angular/core/core.umd.js:3776:27NoAnnotationError@http://localhost:5555/node_modules/@angular/core/core.umd.js:4480:13_extractToken@http://localhost:5555/node_modules/@angular/core/core.umd.js:5027:19_dependenciesFor/<@http://localhost:5555/node_modules/@angular/core/core.umd.js:4979:49_dependenciesFor@http://localhost:5555/node_modules/@angular/core/core.umd.js:4979:16resolveReflectiveFactory@http://localhost:5555/node_modules/@angular/core/core.umd.js:4872:28resolveReflectiveProvider@http://localhost:5555/node_modules/@angular/core/core.umd.js:4895:84resolveReflectiveProviders@http://localhost:5555/node_modules/@angular/core/core.umd.js:4902:24ReflectiveInjector</ReflectiveInjector.resolve@http://localhost:5555/node_modules/@angular/core/core.umd.js:5376:20ReflectiveInjector</ReflectiveInjector.resolveAndCreate@http://localhost:5555/node_modules/@angular/core/core.umd.js:5406:47bootstrap@http://localhost:5555/node_modules/@angular/platform-browser-dynamic/platform-browser-dynamic.umd.js:468:27@http://localhost:5555/app/main.js:12:1@http://localhost:5555/app/main.js:1:1@http://localhost:5555/app/main.js:1:1bootstrap/</</__exec@http://localhost:5555/node_modules/systemjs/dist/system.src.js?1465996676353:1506:1bootstrap/</</</</entry.execute@http://localhost:5555/node_modules/systemjs/dist/system.src.js?1465996676353:3921:11linkDynamicModule@http://localhost:5555/node_modules/systemjs/dist/system.src.js?1465996676353:3247:18link@http://localhost:5555/node_modules/systemjs/dist/system.src.js?1465996676353:3090:11bootstrap/</</</</</<.execute@http://localhost:5555/node_modules/systemjs/dist/system.src.js?1465996676353:3427:13doDynamicExecute@http://localhost:5555/node_modules/systemjs/dist/system.src.js?1465996676353:796:20link@http://localhost:5555/node_modules/systemjs/dist/system.src.js?1465996676353:998:20doLink@http://localhost:5555/node_modules/systemjs/dist/system.src.js?1465996676353:650:7updateLinkSetOnLoad@http://localhost:5555/node_modules/systemjs/dist/system.src.js?1465996676353:698:18proceedToTranslate/</<@http://localhost:5555/node_modules/systemjs/dist/system.src.js?1465996676353:510:11Zone</ZoneDelegate</ZoneDelegate.prototype.invoke@http://localhost:5555/node_modules/zone.js/dist/zone.js?1465996676355:323:20Zone</Zone</Zone.prototype.run@http://localhost:5555/node_modules/zone.js/dist/zone.js?1465996676355:216:25scheduleResolveOrReject/<@http://localhost:5555/node_modules/zone.js/dist/zone.js?1465996676355:571:53Zone</ZoneDelegate</ZoneDelegate.prototype.invokeTask@http://localhost:5555/node_modules/zone.js/dist/zone.js?1465996676355:356:24Zone</Zone</Zone.prototype.runTask@http://localhost:5555/node_modules/zone.js/dist/zone.js?1465996676355:256:29drainMicroTaskQueue@http://localhost:5555/node_modules/zone.js/dist/zone.js?1465996676355:474:26ZoneTask/this.invoke@http://localhost:5555/node_modules/zone.js/dist/zone.js?1465996676355:426:22装饰。相关代码如下：

@Injectable()：

main.ts

import { APP_BASE_HREF } from '@angular/common'; import { enableProdMode, provide } from '@angular/core'; import { bootstrap } from '@angular/platform-browser-dynamic'; import { ROUTER_PROVIDERS } from '@angular/router'; import { MarkdownService } from './shared/index'; import { ProductService, WidgetService, WidgetItemService } from './services/index'; import { AppComponent } from './app.component'; if ('<%= ENV %>' === 'prod') { enableProdMode(); } bootstrap(AppComponent, [ ROUTER_PROVIDERS, ProductService, WidgetService, WidgetItemService, MarkdownService, provide(APP_BASE_HREF, { useValue: '<%= APP_BASE %>' }) ]);：

widget-item.service.ts

import { Injectable } from '@angular/core'; import { Product, Widget, WidgetItem } from '../index'; @Injectable() export class WidgetItemService { private widget_items: Array<WidgetItem> = []; getAll(key: string = null): Promise<any> { return Promise.resolve(this.widget_items); }; constructor() { }; };：

product.service.ts

有什么想法吗？

Answer 1

大多数情况下，如果导入对于您要在构造函数中使用的参数类型不正确，则会出现此错误。

你应该检查一下：

import { Injectable } from '@angular/core';
import { Product, WidgetItem, WidgetItemService } from '../index';

console.log(WidgetItemService); // <----

@Injectable()
export class ProductService {
  constructor(
    private widgetItemService: WidgetItemService
  ) {
  }
}

将@Injectable（）注入另一个@Injectable（）时出错

1 个答案: