Calling observables synchronously one after another in Angular

Question

I have the following service calls available:
productService.GetAllProducts()
productService.DeleteProduct()
productService.GetCategories()
prod

Answer 1

You may want to try something along these lines

productService.GetAllProducts()
.switchMap(
   products => forkJoin(products.map(product => productService.DeleteProduct(product)))
)
.switchMap(() => productService.GetCategories())
.switchMap(
   categories => forkJoin(categories.map(category => productService.DeleteCategory(category)))
)
.subscribe(() => console.log('done'))

The whole idea is the following

• GetAllProducts returns an array of Products which is passed as parameter to the first switchMap
• The Products array is transformed, via map, into an array of Observables which are the result of DeleteProduct - the array of Observable is passed to the first forkJoin as its parameter
• forkJoin emits when all the Observables it has received as parameter complete, and therefore will emit when all the Products have been deleted
• The same reasoning is repeated for categories

I am not sure the code is syntactically perfect, but it should be enough to give you an idea on how to proceed.