From cc1f1b2436368a63c17d484a9b668743e2a3f7cf Mon Sep 17 00:00:00 2001
From: Janne Vuoti <janne.vuoti@reaktor.com>
Date: Wed, 17 Nov 2021 21:40:46 +0200
Subject: [PATCH] Replace array type guard with flatmap

This way no extra utils need to be added.
---
 src/core/queriesObserver.ts | 18 +++++++++---------
 src/core/utils.ts           |  7 -------
 2 files changed, 9 insertions(+), 16 deletions(-)

diff --git a/src/core/queriesObserver.ts b/src/core/queriesObserver.ts
index c9e1d0d7b1..1a32d51e6e 100644
--- a/src/core/queriesObserver.ts
+++ b/src/core/queriesObserver.ts
@@ -1,4 +1,4 @@
-import { difference, notNullOrUndefined, replaceAt } from './utils'
+import { difference, replaceAt } from './utils'
 import { notifyManager } from './notifyManager'
 import type { QueryObserverOptions, QueryObserverResult } from './types'
 import type { QueryClient } from './queryClient'
@@ -77,17 +77,17 @@ export class QueriesObserver extends Subscribable<QueriesObserverListener> {
       this.client.defaultQueryObserverOptions(options)
     )
 
-    const matchingObservers: QueryObserverMatch[] = defaultedQueryOptions
-      .map(defaultedOptions => {
+    const matchingObservers: QueryObserverMatch[] = defaultedQueryOptions.flatMap(
+      defaultedOptions => {
         const match = prevObservers.find(
-          observer => observer.options.queryHash === defaultedOptions.queryHash!
+          observer => observer.options.queryHash === defaultedOptions.queryHash
         )
         if (match != null) {
-          return { defaultedQueryOptions: defaultedOptions, observer: match }
+          return [{ defaultedQueryOptions: defaultedOptions, observer: match }]
         }
-        return null
-      })
-      .filter(notNullOrUndefined)
+        return []
+      }
+    )
 
     const matchedQueryHashes = matchingObservers.map(
       match => match.defaultedQueryOptions.queryHash
@@ -104,7 +104,7 @@ export class QueriesObserver extends Subscribable<QueriesObserverListener> {
 
     const newOrReusedObservers: QueryObserverMatch[] = unmatchedQueries.map(
       (options, index) => {
-        if (options.keepPreviousData && unmatchedObservers.length > 0) {
+        if (options.keepPreviousData) {
           // return previous data from one of the observers that no longer match
           const previouslyUsedObserver = unmatchedObservers[index]
           if (previouslyUsedObserver !== undefined) {
diff --git a/src/core/utils.ts b/src/core/utils.ts
index 41597e6e64..1b01474502 100644
--- a/src/core/utils.ts
+++ b/src/core/utils.ts
@@ -453,10 +453,3 @@ export function getAbortController(): AbortController | undefined {
     return new AbortController()
   }
 }
-
-/**
- * Type predicate to filter an array of null or undefined elements
- */
-export function notNullOrUndefined<T>(value: T): value is NonNullable<T> {
-  return value !== null && value !== undefined
-}