错误错误:未捕获(承诺):错误:StaticInjectorError(AppModule) [英] ERROR Error: Uncaught (in promise): Error: StaticInjectorError(AppModule)

问题描述

我有以下代码:

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

@Injectable()
export class ClientCacheService {
    private _cacheMode: CacheMode;
    private _cacheMode: CacheMode;
    constructor(cache?: CacheMode) {
        if(!cache)
            this._cacheMode = CacheMode.SessionStorage;
        else
            this._cacheMode = cache;
    }

    setToCache(key :string, prefix:string, definition: any) {
        if(this._cacheMode === CacheMode.SessionStorage)
            window.sessionStorage.setItem(`${prefix}_${key}`, JSON.stringify(definition));
        else if(CacheMode.Memory)
            window["`${prefix}_${key}`"] = JSON.stringify(definition);
    }

    getFromCache(key :string, prefix:string) {
        let res = window.sessionStorage.getItem(`${prefix}_${key}`);
        if (res) return JSON.parse(res);

        return undefined;
    }
}
export enum CacheMode{
    Memory,
    LocalStorage,
    SessionStorage
}

当调用类ClientCacheService的构造函数时，将显示以下消息:

When the constructor of the class ClientCacheService is called, it is shown the following message:

ERROR Error: Uncaught (in promise): Error: StaticInjectorError(AppModule)[ClientCacheService -> Number]: 
  StaticInjectorError(Platform: core)[ClientCacheService -> Number]: 
    NullInjectorError: No provider for Number!
Error: StaticInjectorError(AppModule)[ClientCacheService -> Number]: 
  StaticInjectorError(Platform: core)[ClientCacheService -> Number]: 
    NullInjectorError: No provider for Number!

我在this._cacheMode = cacheMode;行上放置了breakpoint，调试器在到达此breakpoint之前启动了错误.

I have put a breakpoint on the line this._cacheMode = cacheMode; and the debugger launches the error before reach this breakpoint.

我不明白为什么会显示此错误.任何人都知道这意味着什么以及如何解决吗?

I'm not understanding why this errors is been shown. Any one have any idea what this means and how to solve it?

推荐答案

您正试图注入不可注入的枚举，您应该为Memory，LocalStorage和SessionStorage实现一个具有单个接口的抽象类，将其称为StorageService例如，接下来您应该像这样在构造函数中使用它:

You are trying to Inject enum that is not injectable, you should implement an abstract class with a single interface for Memory, LocalStorage and SessionStorage, Lets call it StorageService for example, next you should consume it in the constructor like this:

constructor(storageService: StorageService) {}

最后是providers数组

finally the providers array

providers: [
    { provide: StorageService, useClass: Memory} // or LocalStorage or SessionStorage
]

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