Within my Angular application, there are multiple services that have dependencies on each other. To manage this, I have created a dependency map as shown in the example below:
let accountInitialization$: Observable<void>;
let productInitialization$: Observable<void>;
const dependenciesMap = {
accountService: [],
productService: [
accountInitialization$ // There could be one or more dependencies
]
}
accountInitialization$ = this.getDependencies(dependenciesMap.accountService)
.pipe(
mergeMap(_ => {
return this.accountService.initialize();
})
);
productInitialization$ = this.getDependencies(dependenciesMap.productService)
.pipe(
mergeMap(_ => {
return this.productService.initialize();
})
);
accountInitialization$.subscribe(() => {
this.progressUpdate.next(StartUpProgressUpdate.AccountsInitialized);
});
productInitialization$.subscribe(() => {
this.progressUpdate.next(StartUpProgressUpdate.ProductsInitialized);
});
forkJoin([accountInitialization$, productInitialization$]).subscribe(
() => {
// perform some actions after initialization
},
error => {
console.log(error); // This is where errors are handled
}
);
The Product Service relies on the initialization of the Account Service. The getDependencies function has the following structure:
private getDependencies(dependencies: Observable<void>[]) {
if (dependencies.length) {
return forkJoin(dependencies);
}
return EMPTY;
}
In this scenario, the goal is to ensure that the Account Service initializes before the Product Service. However, an error message is being encountered:
ERROR TypeError: You provided 'undefined' where a stream was expected. You can provide an Observable, Promise, Array, or Iterable.
It appears that the .initialize() functions are not being invoked...
If you have any insights on how to resolve this issue, your assistance would be greatly appreciated. Thank you.