Fix returning empty array in getEntityRecords for unknown entities (#…

…36984)

* Fix returning empty array in getEntityRecords for unknown entity

* Add changelog

packages/core-data/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Bug Fixes
+
+-   `getEntityRecords` no longer returns an empty array for unknown entities but returns `null` instead. `hasEntityRecords` now also returns `false` when the entity configuration is unknown. ([#36984](https://github.com/WordPress/gutenberg/pull/36984))
+
 ## 4.0.0 (2021-07-29)
 
 ### Breaking Change

packages/core-data/src/selectors.js

@@ -28,17 +28,6 @@ import { getNormalizedCommaSeparable, isRawAttribute } from './utils';
  */
 const EMPTY_OBJECT = {};
 
-/**
- * Shared reference to an empty array for cases where it is important to avoid
- * returning a new array reference on every invocation, as in a connected or
- * other pure component which performs `shouldComponentUpdate` check on props.
- * This should be used as a last resort, since the normalized data should be
- * maintained by the reducer result in state.
- *
- * @type {Array}
- */
-const EMPTY_ARRAY = [];
-
 /**
  * Returns true if a request is in progress for embed preview data, or false
  * otherwise.
@@ -304,16 +293,14 @@ export function hasEntityRecords( state, kind, name, query ) {
  */
 export function getEntityRecords( state, kind, name, query ) {
 	// Queried data state is prepopulated for all known entities. If this is not
-	// assigned for the given parameters, then it is known to not exist. Thus, a
-	// return value of an empty array is used instead of `null` (where `null` is
-	// otherwise used to represent an unknown state).
+	// assigned for the given parameters, then it is known to not exist.
 	const queriedState = get( state.entities.data, [
 		kind,
 		name,
 		'queriedData',
 	] );
 	if ( ! queriedState ) {
-		return EMPTY_ARRAY;
+		return null;
 	}
 	return getQueriedItems( queriedState, query );
 }

packages/core-data/src/test/selectors.js

@@ -160,14 +160,14 @@ describe( 'hasEntityRecords', () => {
 		expect( hasEntityRecords( state, 'root', 'postType' ) ).toBe( false );
 	} );
 
-	it( 'returns true if the entity configuration is not known', () => {
+	it( 'returns false if the entity configuration is not known', () => {
 		const state = deepFreeze( {
 			entities: {
 				data: {},
 			},
 		} );
 
-		expect( hasEntityRecords( state, 'root', 'postType' ) ).toBe( true );
+		expect( hasEntityRecords( state, 'root', 'postType' ) ).toBe( false );
 	} );
 
 	it( 'returns true if entity records have been received', () => {
@@ -295,14 +295,14 @@ describe( 'getEntityRecords', () => {
 		expect( getEntityRecords( state, 'root', 'postType' ) ).toBe( null );
 	} );
 
-	it( 'should return an empty array for an unknown entity configuration', () => {
+	it( 'should return null for an unknown entity configuration', () => {
 		const state = deepFreeze( {
 			entities: {
 				data: {},
 			},
 		} );
 
-		expect( getEntityRecords( state, 'root', 'postType' ) ).toEqual( [] );
+		expect( getEntityRecords( state, 'root', 'postType' ) ).toBe( null );
 	} );
 
 	it( 'should return all the records', () => {