7

我在这里看到很多类似的问题，但还没有找到有效的解决方案。我认为正在发生的事情是，因为我们的 Ng2App 首先被引导，它还没有对 $injector 的引用，所以当我尝试在我的提供程序声明中使用它时（deps: ['$injector']），它没有'不存在。

非常奇怪的是，我可以在 Angular COMPONENT 中使用此服务，但由于某种原因不能在 Angular SERVICE 中使用它。

应用程序.js

import UserService from './user.service';
angular.module('app', [])
  .service('UserService', UserService)
  .config(/* config */)
  .run(/* run */);

 import './ng2app.module';

ng2app.module.ts：

import { BrowserModule } from '@angular/platform-browser';
import { UpgradeModule } from '@angular/upgrade/static';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule,
  ], 
  declarations: [],
  entryComponents: [],
  providers: [
    // angularJS service:
    { 
     provide: 'UserService',
     useFactory: (i: any) => i.get('UserService'), // <---- this is the line all the errors point to.
     deps: ['$injector']
    },
  ]
})
export default class Ng2AppModule {
  constructor(){}
}


platformBrowserDynamic()
  .bootstrapModule(Ng2AppModule)
  .then(platformRef => {
    const upgrade = platformRef.injector.get(UpgradeModule) as UpgradeModule;
    upgrade.bootstrap(document.documentElement, ['app'], {strictDi: true});
});

后来......在服务中（失败）：

import {Injectable, Inject} from "@angular/core";
import UserService from 'app/login/user.service';

@Injectable()
export class AnAngularService{
  constructor(
    // causes the error if I uncomment it wtf: <--------------
    // @Inject('UserService') private userService: UserService
  ){}
}

后来......在一个组件中（正常工作）：

import { Component } from '@angular/core';
import {Inject} from "@angular/core";
import UserService from 'app/login/user.service';
import template from 'tmpl.html';

@Component({
  selector: 'an-angular-component',
  template,
})
export class AnAngularComponent{
  constructor(

    @Inject('UserService') private userService: UserService
  ){
    console.log(userService) // works just fine. wtf <--------------
  }
}

有谁知道为什么会发生这种情况以及如何解决？

这个问题几乎完全相同，但由于某种原因它不起作用

AngularJS 版本：1.5.8
Angular/core 等版本：4.2.4

这是我在 Angular 存储库中打开的 Github 问题的链接

堆栈跟踪：

zone.js:522 Unhandled Promise rejection: Cannot read property 'get' of undefined ; Zone: <root> ; Task: Promise.then ; Value: TypeError: Cannot read property 'get' of undefined
    at useFactory (ng2app.module.ts:114)
    at _callFactory (core.es5.js:9604)
    at _createProviderInstance$1 (core.es5.js:9547)
    at initNgModule (core.es5.js:9498)
    at new NgModuleRef_ (core.es5.js:10606)
    at createNgModuleRef (core.es5.js:10590)
    at Object.debugCreateNgModuleRef [as createNgModuleRef] (core.es5.js:12874)
    at NgModuleFactory_.create (core.es5.js:13869)
    at core.es5.js:4556
    at ZoneDelegate.invoke (zone.js:334)
    at Object.onInvoke (core.es5.js:3933)
    at ZoneDelegate.invoke (zone.js:333)
    at Zone.run (zone.js:126)
    at NgZone.run (core.es5.js:3801)
    at PlatformRef_._bootstrapModuleFactoryWithZone (core.es5.js:4554)
    at core.es5.js:4596
    at ZoneDelegate.invoke (zone.js:334)
    at Zone.run (zone.js:126)
    at zone.js:713
    at ZoneDelegate.invokeTask (zone.js:367)
    at Zone.runTask (zone.js:166)
    at drainMicroTaskQueue (zone.js:546)
    at <anonymous> TypeError: Cannot read property 'get' of undefined
    at useFactory (http://localhost:9000/app.bundle.js:4404:52)
    at _callFactory (http://localhost:9000/vendor.bundle.js:10600:26)
    at _createProviderInstance$1 (http://localhost:9000/vendor.bundle.js:10543:26)
    at initNgModule (http://localhost:9000/vendor.bundle.js:10494:13)
    at new NgModuleRef_ (http://localhost:9000/vendor.bundle.js:11602:9)
    at createNgModuleRef (http://localhost:9000/vendor.bundle.js:11586:12)
    at Object.debugCreateNgModuleRef [as createNgModuleRef] (http://localhost:9000/vendor.bundle.js:13870:12)
    at NgModuleFactory_.create (http://localhost:9000/vendor.bundle.js:14865:25)
    at http://localhost:9000/vendor.bundle.js:5552:61
    at ZoneDelegate.invoke (http://localhost:9000/vendor.bundle.js:289131:26)
    at Object.onInvoke (http://localhost:9000/vendor.bundle.js:4929:37)
    at ZoneDelegate.invoke (http://localhost:9000/vendor.bundle.js:289130:32)
    at Zone.run (http://localhost:9000/vendor.bundle.js:288923:43)
    at NgZone.run (http://localhost:9000/vendor.bundle.js:4797:62)
    at PlatformRef_._bootstrapModuleFactoryWithZone (http://localhost:9000/vendor.bundle.js:5550:23)
    at http://localhost:9000/vendor.bundle.js:5592:59
    at ZoneDelegate.invoke (http://localhost:9000/vendor.bundle.js:289131:26)
    at Zone.run (http://localhost:9000/vendor.bundle.js:288923:43)
    at http://localhost:9000/vendor.bundle.js:289510:57
    at ZoneDelegate.invokeTask (http://localhost:9000/vendor.bundle.js:289164:31)
    at Zone.runTask (http://localhost:9000/vendor.bundle.js:288963:47)
    at drainMicroTaskQueue (http://localhost:9000/vendor.bundle.js:289343:35)
    at <anonymous>
consoleError @ zone.js:522
handleUnhandledRejection @ zone.js:527
_loop_1 @ zone.js:562
drainMicroTaskQueue @ zone.js:566
Promise resolved (async)
scheduleQueueDrain @ zone.js:505
scheduleMicroTask @ zone.js:513
ZoneDelegate.scheduleTask @ zone.js:356
Zone.scheduleTask @ zone.js:196
Zone.scheduleMicroTask @ zone.js:207
scheduleResolveOrReject @ zone.js:711
ZoneAwarePromise.then @ zone.js:800
PlatformRef_._bootstrapModuleWithZone @ core.es5.js:4596
PlatformRef_.bootstrapModule @ core.es5.js:4581
(anonymous) @ ng2app.module.ts:140
__webpack_require__ @ bootstrap 2f644bad14cb0bb324ab:691
fn @ bootstrap 2f644bad14cb0bb324ab:110
(anonymous) @ app.js:116
__webpack_require__ @ bootstrap 2f644bad14cb0bb324ab:691
fn @ bootstrap 2f644bad14cb0bb324ab:110
(anonymous) @ util (ignored):1
__webpack_require__ @ bootstrap 2f644bad14cb0bb324ab:691
webpackJsonpCallback @ bootstrap 2f644bad14cb0bb324ab:23
(anonymous) @ app.bundle.js:1
4

3 回答 3

3

似乎是时间@NgModule({ providers: [] })和upgrade.bootstrap分辨率的问题。

在这里你需要它，$injector但它在被请求的那一刻没有被注入。

在文档中它说你应该使用ngDoBootstrap钩子。

export function userServiceFactory(i: any) {
  return i.get('UserService');
}

export const userServiceProvider = {
  provide: 'UserService',
  useFactory: userServiceFactory,
  deps: ['$injector']
};

import { BrowserModule } from '@angular/platform-browser';
import { UpgradeModule } from '@angular/upgrade/static';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule,
  ], 
  declarations: [],
  entryComponents: [],
  providers: [
     userServiceProvider
  ]
}) 


export default class Ng2AppModule {

   constructor(private upgrade: UpgradeModule) { }

   ngDoBootstrap() {
     this.upgrade.bootstrap(document.body, ['app'], { strictDi: true });
   }
}

platformBrowserDynamic().bootstrapModule(Ng2AppModule);

由 andrew luhring 为后人编辑 不幸的是，即使这正是 angular 文档中所写的内容，但这也不起作用。这里的原始答案是：

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

useFactory: (forwardRef(() => '$injector')i: any) => i.get('UserService')

这似乎比这更接近答案。这也不起作用——但这似乎是因为 TypeScript 认为语法不正确。

更新：

我们非常痴迷于useFactory我们没有看到修复只是添加forwardRef到服务中。

@Injectable()
export class AnAngularService{
  constructor(@Inject(forwardRef(() => 'UserService')) private userService: UserService
  ){}
}
于 2017-08-14T17:48:22.510 回答
3

好的，所以我想出了一个技巧来让它工作。这是超级恶心，但它的工作原理。必须有一个更好的解决方案，所以我没有将其标记为已解决，并且提出更好解决方案的人仍然会获得赏金。

import { BrowserModule } from '@angular/platform-browser';
import { UpgradeModule } from '@angular/upgrade/static';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule,
  ], 
  declarations: [],
  entryComponents: [],
  providers: [
    // angularJS service:
    {
      provide: 'UserService',
      useFactory: () => {
        return new Promise((resolve) => {
          setTimeout(function(){
            resolve(angular.element(document)
                .injector().get('UserService'))
          },1);
        })
      },
      deps: []
    },

  ]
})
export default class Ng2AppModule {
  constructor(){}
}

^ 返回一个承诺并使用 setTimeout 在解析 angularJS 注入器之前等待下一个滴答声。

在您的服务中：

import {Injectable, Inject} from "@angular/core";
import UserService from 'app/login/user.service';

@Injectable()
export class AnAngularService{
  constructor(
    @Inject('UserService') private userService: any,
  ){

    userService.then(function(_userService){
       _userService.doAThing();
    });
    }
}

在您的组件中：

import { Component } from '@angular/core';
import {Inject} from "@angular/core";
import UserService from 'app/login/user.service';
import template from 'tmpl.html';

@Component({
  selector: 'an-angular-component',
  template,
})
export class AnAngularComponent{
  constructor(
    @Inject('UserService') private userService: any,
  ){
    userService.then((us)=>{ console.log(us); })
  }
}

是的。这行得通。但这是一个黑客。所以这是可能的。我怎样才能以一种不那么老套的方式做到这一点？

于 2017-08-14T17:19:56.603 回答
0

我能够通过使用 Angular CoreInjector类在需要时获取升级的 AngularJs 服务来解决这个问题，而不是在构造函数中注入它。

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

@Injectable()
class MyAngularService {
  constructor(private injector: Injector) {
    //
  }

  myMethodUsingUpgradedService() {
    const myAngularJsUpgradedService = this.injector('MyAngularJsUpgradedService');

    // myAngularJsUpgradedService is now available
  }
}
于 2018-03-08T15:42:26.113 回答