从 Angular 4 升级到 5.0.1 时出现“未捕获的错误:无法解析所有参数"的运行时错误

问题描述

这在 Angular 4.x 中很好，只是在 Angular 5.0.1 中不行.此项目是使用 Angular CLI 生成的.

This is fine in Angular 4.x, just not Angular 5.0.1. This project was generated with Angular CLI.

compiler.js:466 Uncaught Error: Can't resolve all parameters for RegistrationService: (?).
    at syntaxError (compiler.js:466)
    at CompileMetadataResolver._getDependenciesMetadata (compiler.js:15546)
    at CompileMetadataResolver._getTypeMetadata (compiler.js:15381)
    at CompileMetadataResolver._getInjectableMetadata (compiler.js:15361)
    at CompileMetadataResolver.getProviderMetadata (compiler.js:15721)
    at eval (compiler.js:15632)
    at Array.forEach (<anonymous>)
    at CompileMetadataResolver._getProvidersMetadata (compiler.js:15592)
    at CompileMetadataResolver.getNgModuleMetadata (compiler.js:15160)
    at CompileMetadataResolver.getNgModuleSummary (compiler.js:14998)
syntaxError @ compiler.js:466
CompileMetadataResolver._getDependenciesMetadata @ compiler.js:15546
CompileMetadataResolver._getTypeMetadata @ compiler.js:15381
CompileMetadataResolver._getInjectableMetadata @ compiler.js:15361
CompileMetadataResolver.getProviderMetadata @ compiler.js:15721
(anonymous) @ compiler.js:15632
CompileMetadataResolver._getProvidersMetadata @ compiler.js:15592
CompileMetadataResolver.getNgModuleMetadata @ compiler.js:15160
CompileMetadataResolver.getNgModuleSummary @ compiler.js:14998
(anonymous) @ compiler.js:15086
CompileMetadataResolver.getNgModuleMetadata @ compiler.js:15071
JitCompiler._loadModules @ compiler.js:33486
JitCompiler._compileModuleAndComponents @ compiler.js:33447
JitCompiler.compileModuleAsync @ compiler.js:33363
CompilerImpl.compileModuleAsync @ platform-browser-dynamic.js:230
PlatformRef.bootstrapModule @ core.js:5446
(anonymous) @ main.ts:12
../../../../../src/main.ts @ main.bundle.js:640
__webpack_require__ @ inline.bundle.js:55
1 @ main.bundle.js:670
__webpack_require__ @ inline.bundle.js:55
webpackJsonpCallback @ inline.bundle.js:26
(anonymous) @ main.bundle.js:1

这是构造函数的样子:

     constructor(
    private apiHelperService: ApiHelperService
  ) {
  }

该类有@Injectable()

The class has @Injectable()

    @Injectable()
export class ApiHelperService {

它也已正确导入到模块提供程序中.

It has also properly imported into the module providers.

providers: [
    AuthGuard,
    ApiHelperService,

如果我把它改成这个，那么错误就会消失并且它可以工作，但是它希望你将整个解决方案中的每个构造函数更改为这个语法，我认为这是不正确的.

If I change it to this, then the error goes away and it works, but then it wants you to change every constructor in the entire solution to this syntax, which I don't believe to be correct.

@Inject(ApiHelperService) private apiHelperService: ApiHelperService

这是我的 tsconfig.json，它确实已将 emitDecoratorMetadata 正确设置为 true

Here is my tsconfig.json, which does have emitDecoratorMetadata properly set to true

{
  "compileOnSave": false,
  "compilerOptions": {
    "outDir": "./dist/out-tsc",
    "baseUrl": "src",
    "sourceMap": true,
    "declaration": false,
    "moduleResolution": "node",
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "target": "es5",
    "typeRoots": [
      "node_modules/@types"
    ],
    "lib": [
      "es2017",
      "dom"
    ]
  }
}

推荐答案

在 Angular 5 更新博客文章 作者提到他们使用的是静态注入器而不是基于反射的注入器，并提到不再需要反射 polyfills，但在我的情况下它是.

In Angular 5 Update blog post the author mentions that they are using a static injector instead of a reflection based one and mentions that the reflection polyfills are no longer needed but in my case it was.

如果您删除了反射的 polyfill，请尝试再次添加它们:

If you removed the polyfills for reflections try adding them again:

import 'core-js/es6/reflect';
import 'core-js/es7/reflect';

我希望它也适合你.

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