Implement a shared service between a library and an Angular consumer

Issue

I have a shared service between the different modules in my Angular application and I have implemented an Angular library. I want to use the shared service in the library too, i.e. if a data is updated in the consumer I want the library to be updated too.

I tried to use consumer in the app.module:

providers:[{provide: 'ParameterStorageService', useClass:ParameterStorageService},

in the library:

forRoot(ParameterStorageService) : ModuleWithProviders<any>{
    return {
      ngModule:CompanyAndDealModule,
      providers:[
        {provide: 'ParameterStorageService',useClass:ParameterStorageService}] 

The problem that the data is not updated in the library when it is modified in the consumer.

Solution

As described by @jonrsharpe: "useClass will create a new instance each time", so I changed useClass to useExisting and it works.

providers:[{provide: 'ParameterStorageService', useExisting:ParameterStorageService}

Answered By - YASSIN SLAMA