Ported fix of existsByID API to SB3

sdk/spring/azure-spring-data-cosmos/CHANGELOG.md

@@ -9,6 +9,7 @@
 
 #### Bugs Fixed
 * Fixed all saveAll/insertAll bulk functionality to populated audit data - See [PR 39811](https://github.com/Azure/azure-sdk-for-java/pull/39811).
+* Fixed `existsById` API in `ReactiveCosmosTemplate` to return `Mono<Boolean>` containing `False` in case the item does not exist - See [PR 40050](https://github.com/Azure/azure-sdk-for-java/pull/40050).
 
 #### Other Changes
 

sdk/spring/azure-spring-data-cosmos/src/main/java/com/azure/spring/data/cosmos/core/ReactiveCosmosTemplate.java

@@ -850,7 +850,8 @@ public Mono<Boolean> exists(CosmosQuery query, Class<?> domainType, String conta
      */
     public Mono<Boolean> existsById(Object id, Class<?> domainType, String containerName) {
         return findById(containerName, id, domainType)
-            .flatMap(o -> Mono.just(o != null));
+            .flatMap(o -> Mono.just(o != null))
+            .switchIfEmpty(Mono.just(false));
     }
 
     /**

sdk/spring/azure-spring-data-cosmos/src/test/java/com/azure/spring/data/cosmos/core/ReactiveCosmosTemplateIT.java

@@ -714,6 +714,26 @@ public void testExists() {
         Assertions.assertThat(responseDiagnosticsTestUtils.getCosmosResponseStatistics().getRequestCharge()).isGreaterThan(0);
     }
 
+    @Test
+    public void testNotExists() {
+        final Criteria criteria = Criteria.getInstance(CriteriaType.IS_EQUAL, "firstName",
+            Collections.singletonList("randomFirstName"), Part.IgnoreCaseType.NEVER);
+        final CosmosQuery query = new CosmosQuery(criteria);
+        final Mono<Boolean> exists = cosmosTemplate.exists(query, Person.class, containerName);
+        StepVerifier.create(exists).expectNext(false).verifyComplete();
+
+        // add ignore testing
+        final Criteria criteriaIgnoreCase = Criteria.getInstance(CriteriaType.IS_EQUAL, "firstName",
+            Collections.singletonList("randomFirstName".toUpperCase()), Part.IgnoreCaseType.ALWAYS);
+        final CosmosQuery queryIgnoreCase = new CosmosQuery(criteriaIgnoreCase);
+        final Mono<Boolean> existsIgnoreCase = cosmosTemplate.exists(queryIgnoreCase, Person.class, containerName);
+        StepVerifier.create(existsIgnoreCase).expectNext(false).verifyComplete();
+
+        assertThat(responseDiagnosticsTestUtils.getCosmosDiagnostics()).isNotNull();
+        Assertions.assertThat(responseDiagnosticsTestUtils.getCosmosResponseStatistics()).isNotNull();
+        Assertions.assertThat(responseDiagnosticsTestUtils.getCosmosResponseStatistics().getRequestCharge()).isGreaterThan(0);
+    }
+
     @Test
     public void testCount() {
         final Mono<Long> count = cosmosTemplate.count(containerName);

sdk/spring/azure-spring-data-cosmos/src/test/java/com/azure/spring/data/cosmos/repository/ReactiveUUIDIdDomainRepositoryIT.java

@@ -150,6 +150,9 @@ public void testExistsById() {
 
         Mono<Boolean> booleanMono = this.repository.existsById(DOMAIN_1.getNumber());
         StepVerifier.create(booleanMono).expectNext(true).expectComplete().verify();
+
+        booleanMono = this.repository.existsById(UUID.randomUUID());
+        StepVerifier.create(booleanMono).expectNext(false).expectComplete().verify();
     }
 
     private static class InvalidDomain {

sdk/spring/azure-spring-data-cosmos/src/test/java/com/azure/spring/data/cosmos/repository/integration/ReactiveLongIdDomainPartitionPartitionRepositoryIT.java

@@ -171,6 +171,9 @@ public void testExistsById() {
 
         Mono<Boolean> booleanMono = this.repository.existsById(DOMAIN_1.getNumber());
         StepVerifier.create(booleanMono).expectNext(true).expectComplete().verify();
+
+        booleanMono = this.repository.existsById(0L);
+        StepVerifier.create(booleanMono).expectNext(false).expectComplete().verify();
     }
 
     @Test