Adding to reactive.

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

@@ -336,6 +336,15 @@ Mono<CosmosContainerProperties> replaceContainerProperties(String containerName,
      */
     Mono<Long> count(SqlQuerySpec querySpec, String containerName);
 
+    /**
+     * Sum
+     *
+     * @param querySpec the document query spec
+     * @param containerName the container name
+     * @return sum result
+     */
+    Mono<Long> sum(SqlQuerySpec querySpec, String containerName);
+
     /**
      * To get converter
      * @return MappingCosmosConverter

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

@@ -920,7 +920,7 @@ public Mono<Long> count(String containerName) {
     @Override
     public Mono<Long> count(CosmosQuery query, String containerName) {
         final SqlQuerySpec querySpec = new CountQueryGenerator().generateCosmos(query);
-        return getCountValue(querySpec, containerName);
+        return getNumericValue(querySpec, containerName);
     }
 
     /**
@@ -932,7 +932,19 @@ public Mono<Long> count(CosmosQuery query, String containerName) {
      */
     @Override
     public Mono<Long> count(SqlQuerySpec querySpec, String containerName) {
-        return getCountValue(querySpec, containerName);
+        return getNumericValue(querySpec, containerName);
+    }
+
+    /**
+     * Sum
+     *
+     * @param querySpec the document query spec
+     * @param containerName the container name
+     * @return Mono with sum or error
+     */
+    @Override
+    public Mono<Long> sum(SqlQuerySpec querySpec, String containerName) {
+        return getNumericValue(querySpec, containerName);
     }
 
     @Override
@@ -975,7 +987,7 @@ private Flux<JsonNode> runQuery(SqlQuerySpec querySpec, Class<?> domainType) {
                                           this.responseDiagnosticsProcessor));
     }
 
-    private Mono<Long> getCountValue(SqlQuerySpec querySpec, String containerName) {
+    private Mono<Long> getNumericValue(SqlQuerySpec querySpec, String containerName) {
         final CosmosQueryRequestOptions options = new CosmosQueryRequestOptions();
         options.setQueryMetricsEnabled(this.queryMetricsEnabled);
         options.setIndexMetricsEnabled(this.indexMetricsEnabled);
@@ -987,7 +999,7 @@ private Mono<Long> getCountValue(SqlQuerySpec querySpec, String containerName) {
             .doOnNext(feedResponse -> CosmosUtils.fillAndProcessResponseDiagnostics(this.responseDiagnosticsProcessor,
                 feedResponse.getCosmosDiagnostics(), feedResponse))
             .onErrorResume(throwable ->
-                CosmosExceptionUtils.exceptionHandler("Failed to get count value", throwable,
+                CosmosExceptionUtils.exceptionHandler("Failed to get numeric value", throwable,
                     this.responseDiagnosticsProcessor))
             .next()
             .map(r -> r.getResults().get(0).asLong());

sdk/spring/azure-spring-data-cosmos/src/main/java/com/azure/spring/data/cosmos/repository/support/StringBasedReactiveCosmosQuery.java

@@ -96,8 +96,10 @@ public Object execute(final Object[] parameters) {
         SqlQuerySpec querySpec = new SqlQuerySpec(stripExtraWhitespaceFromString(expandedQuery), sqlParameters);
         if (isCountQuery()) {
             final String container = ((SimpleReactiveCosmosEntityMetadata<?>) getQueryMethod().getEntityInformation()).getContainerName();
-            final Mono<Long> mono = this.operations.count(querySpec, container);
-            return mono;
+            return this.operations.count(querySpec, container);
+        } else if (isSumQuery()) {
+            final String container = ((SimpleReactiveCosmosEntityMetadata<?>) getQueryMethod().getEntityInformation()).getContainerName();
+            return this.operations.sum(querySpec, container);
         } else {
             Flux<?> flux = this.operations.runQuery(querySpec, accessor.getSort(), processor.getReturnedType().getDomainType(),
                                                     processor.getReturnedType().getReturnedType());
@@ -123,4 +125,8 @@ protected boolean isCountQuery() {
         return StringBasedCosmosQuery.isCountQuery(query, getQueryMethod().getReturnedObjectType());
     }
 
+    protected boolean isSumQuery() {
+        return StringBasedCosmosQuery.isSumQuery(query, getQueryMethod().getReturnedObjectType());
+    }
+
 }

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

@@ -35,8 +35,11 @@ public class ReactiveLongIdDomainPartitionPartitionRepositoryIT {
     private static final Long ID_2 = 67890L;
     private static final String NAME_2 = "camille";
 
+    private static final Long ID_3 = 98765L;
+
     private static final LongIdDomainPartition DOMAIN_1 = new LongIdDomainPartition(ID_1, NAME_1);
     private static final LongIdDomainPartition DOMAIN_2 = new LongIdDomainPartition(ID_2, NAME_2);
+    private static final LongIdDomainPartition DOMAIN_3 = new LongIdDomainPartition(ID_3, NAME_1);
 
     @ClassRule
     public static final ReactiveIntegrationTestCollectionManager collectionManager = new ReactiveIntegrationTestCollectionManager();
@@ -192,6 +195,18 @@ public void testFindAllSort() {
         StepVerifier.create(descAllFlux).expectNext(DOMAIN_2, other, DOMAIN_1).verifyComplete();
     }
 
+    @Test
+    public void testSum() {
+        Mono<Long> sum1 = this.repository.annotatedSumLongIdValuesByName(NAME_1);
+        StepVerifier.create(sum1).expectNext(12345L).verifyComplete();
+
+        Mono<LongIdDomainPartition> saveMono = this.repository.save(DOMAIN_3);
+        StepVerifier.create(saveMono).expectNext(DOMAIN_3).expectComplete().verify();
+
+        Mono<Long> sum2 = this.repository.annotatedSumLongIdValuesByName(NAME_1);
+        StepVerifier.create(sum2).expectNext(111110L).verifyComplete();
+    }
+
     private static class InvalidDomain {
 
         private long count;

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

@@ -3,10 +3,16 @@
 package com.azure.spring.data.cosmos.repository.repository;
 
 import com.azure.spring.data.cosmos.domain.LongIdDomainPartition;
+import com.azure.spring.data.cosmos.repository.Query;
 import com.azure.spring.data.cosmos.repository.ReactiveCosmosRepository;
+import org.springframework.data.repository.query.Param;
 import org.springframework.stereotype.Repository;
+import reactor.core.publisher.Mono;
 
 @Repository
 public interface ReactiveLongIdDomainPartitionRepository extends ReactiveCosmosRepository<LongIdDomainPartition, Long> {
 
+    @Query("SELECT VALUE SUM(a.number) from a where a.name = @name")
+    Mono<Long> annotatedSumLongIdValuesByName(@Param("name") String name);
+
 }