Angular 2 Di不起作用-无法解析所有参数 [英] Angular 2 Di not working - cannot resolve all parameters for

问题描述

我已经创建了一个运行良好的简单Hello World应用.但是，当我只想添加一个服务"时，会出现以下错误:

I've created a simple Hello World app that works fine. But when I want to add a "Service" just a simple Di I got the following errors:

angular2.dev.js:23877例外:无法解析'AppComponent'(?)的所有参数.确保所有参数都用Inject修饰或具有有效的类型注释，并且'AppComponent'用Injectable修饰.

angular2.dev.js:23877 EXCEPTION: Cannot resolve all parameters for 'AppComponent'(?). Make sure that all the parameters are decorated with Inject or have valid type annotations and that 'AppComponent' is decorated with Injectable.

angular2-polyfills.js:469未处理的承诺拒绝:无法解析"AppComponent"(?)的所有参数.确保所有参数都用Inject修饰或具有有效的类型注释，并且'AppComponent'用Injectable修饰. ;区域:角；任务:Promise.then;值:

angular2-polyfills.js:469 Unhandled Promise rejection: Cannot resolve all parameters for 'AppComponent'(?). Make sure that all the parameters are decorated with Inject or have valid type annotations and that 'AppComponent' is decorated with Injectable. ; Zone: angular ; Task: Promise.then ; Value:

我有3个文件

boot.ts:

///<reference path="../../node_modules/angular2/typings/browser.d.ts"/>
import {bootstrap} from 'angular2/platform/browser'
import {AppComponent} from './mainApp'
bootstrap(AppComponent);

mainApp.ts:

mainApp.ts:

import {Component} from 'angular2/core';
import {CourseService} from './course.service';


@Component({
    selector: 'my-app',
    template: 'My First Angular 2 App',
    providers: [CourseService],
})
export class AppComponent {
    constructor(courseService: CourseService) {
    }
} 

course.service.ts:

course.service.ts:

export class CourseService {
   public getCourses(): string[] {
      let courses: string[] = ["Course 1", "Course 2", "Course 3"];
      return courses;
  }
}

当我从构造函数中删除参数时，一切正常.

when I remove then parameters from the constructor every thing works fine.

那是我的HTML文档的开头，我可能使用的是beta 2 beta 13:

thats the head of my HTML document and I ma using angular 2 beta 13:

<script src="~/Scripts/es6-shim.min.js"></script>
<script src="~/Scripts/system-polyfills.js"></script>
<script src="~/Scripts/shims_for_IE.js"></script>
<script src="~/Scripts/angular2-polyfills.js"></script>
<script src="~/Scripts/system.js"></script>
<script src="~/Scripts/Rx.js"></script>
<script src="~/Scripts/angular2.dev.js"></script>

<!-- 2. Configure SystemJS -->
<script>
    System.config({
        packages: {
            'ScriptsApp/views': {
                defaultExtension: 'js'
            }
        }
    });
</script>
<script>
    System.import('ScriptsApp/views/boot').then(null, console.error.bind(console));
</script>

现在更新这些是我的固定csproj TypeScript设置

Update these are NOW my Fixed csproj TypeScript Settings

<TypeScriptTarget>ES5</TypeScriptTarget>
<TypeScriptJSXEmit>None</TypeScriptJSXEmit>
<TypeScriptCompileOnSaveEnabled>True</TypeScriptCompileOnSaveEnabled>
<TypeScriptNoImplicitAny>False</TypeScriptNoImplicitAny>
<TypeScriptModuleKind>CommonJS</TypeScriptModuleKind>
<TypeScriptRemoveComments>False</TypeScriptRemoveComments>
<TypeScriptOutFile />
<TypeScriptOutDir />
<TypeScriptGeneratesDeclarations>False</TypeScriptGeneratesDeclarations>
<TypeScriptNoEmitOnError>True</TypeScriptNoEmitOnError>
<TypeScriptSourceMap>True</TypeScriptSourceMap>
<TypeScriptMapRoot />
<TypeScriptSourceRoot />
<TypeScriptExperimentalDecorators>True</TypeScriptExperimentalDecorators>
<TypeScriptEmitDecoratorMetadata>True</TypeScriptEmitDecoratorMetadata>

在最新的VS 2015更新中，您还可以使用tsconfig.json，然后将忽略TypeScript的解决方案设置.我当前的tsconfig.json示例:

In the Newest VS 2015 Update you can also use the tsconfig.json, then the Solution Settings for TypeScript are ignored. My current example for my tsconfig.json:

 {
  "compilerOptions": {
    "target": "es5",
    "module": "commonjs",
    "moduleResolution": "node",
    "sourceMap": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "removeComments": false,
    "noImplicitAny": false,
    //Kümmert sich um die Typings das diese entsprechend gefunden werden, keine Reference mehr in boot.js notwendig. Geht aber in VS nicht!
    //"lib": ["es6"],
    "types": [
      "node" //wird für RequireJs benötigt, damit z.b. der Typ gefunden werden kann
    ]
  },
  //Wird für den AwesomeTypeScriptLoad in WebPack benötigt!
   "awesomeTypescriptLoaderOptions": {
     "useWebpackText": true
   },
  "exclude": [
       "node_modules",
       "dist",
       "typings/main",
       "typings/index.d.ts"
     ],
     "compileOnSave": true
   }

推荐答案

更新

有问题的更新后，OP已经在使用Typescript，建议您在tsconfig.json内添加emitDecoratorMetadata: true.因此，JavaScript输出必须在转译的脚本文件中为装饰器创建元数据.

After update in question OP is using Typescript already, I'd suggest you to add emitDecoratorMetadata: true inside your tsconfig.json. It is necessary so the JavaScript output creates the metadata for the decorators inside a transpiled script file.

您需要添加@Inject在AppComponent

constructor(@Inject(CourseService) courseService: CourseService) {
}

如果您使用的是打字稿，则无需在其中放置@Inject装饰器.打字稿为您做到了.

In a case if you are using typescript, you don't need to have @Inject decorator there in place. Typescript done that for you.

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