ERROR Error: Uncaught (in promise): Error: StaticInjectorError(AppModule)

问题

I have the following code:

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
}

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!

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

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

回答1:

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) {}

finally the providers array

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

来源：https://stackoverflow.com/questions/51267560/error-error-uncaught-in-promise-error-staticinjectorerrorappmodule

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typescript

angular5