---
title: Multiple service calls from an Effect
slug: multiple-service-calls-from-an-effect
description: A snippet on how to invoke multiple service calls within a single NgRx Effect.
date: 2019-12-18
tags: ngrx, angular
---

## Multiple service calls from an Effect

### Use case

An action to fetch multiple entities at once, but the service has only an endpoint to fetch one entity at a time.

### Solution

Use the RxJS [merge](https://rxjs.dev/api/index/function/merge) operator to flatten all request streams and concurrently emit all values to a single output stream.

```ts
refresh$ = createEffect(() =>
	this.actions$.pipe(
		ofType(CustomerActions.refresh),
		exhaustMap(({ customerIds }) =>
			merge(
				...ids.map((id) =>
					this.customersService.getCustomer(id).pipe(
						map(CustomerActions.getCustomerSuccess),
						catchError((err) => of(CustomerActions.getCustomerFailed(id, err.message))),
					),
				),
			),
		),
	),
);
```