Throw an explicit exception if count query does not return a count. (#1195)

Also just use the first projected property instead of one explicitly named "count".

Closes #925,#960.

src/main/java/org/springframework/data/couchbase/core/ExecutableFindByQueryOperationSupport.java

@@ -19,6 +19,7 @@ import java.util.List;
 import java.util.stream.Stream;
 
 import org.springframework.data.couchbase.core.ReactiveFindByQueryOperationSupport.ReactiveFindByQuerySupport;
+import org.springframework.data.couchbase.core.CouchbaseQueryExecutionException;
 import org.springframework.data.couchbase.core.query.Query;
 import org.springframework.util.Assert;
 
@@ -142,7 +143,11 @@ public class ExecutableFindByQueryOperationSupport implements ExecutableFindByQu
 
 		@Override
 		public long count() {
-			return reactiveSupport.count().block();
+			Long l = reactiveSupport.count().block();
+			if ( l == null ){
+				throw new CouchbaseQueryExecutionException("count query did not return a count : "+query.export());
+			}
+			return l;
 		}
 
 		@Override

src/main/java/org/springframework/data/couchbase/core/ReactiveFindByQueryOperationSupport.java

@@ -217,7 +217,8 @@ public class ReactiveFindByQueryOperationSupport implements ReactiveFindByQueryO
 				} else {
 					return throwable;
 				}
-			}).flatMapMany(ReactiveQueryResult::rowsAsObject).map(row -> row.getLong(TemplateUtils.SELECT_COUNT)).next());
+			}).flatMapMany(ReactiveQueryResult::rowsAsObject).map(row -> row.getLong(row.getNames().iterator().next()))
+					.next());
 		}
 
 		@Override

src/test/java/org/springframework/data/couchbase/domain/AirportRepository.java

@@ -114,6 +114,12 @@ public interface AirportRepository extends CouchbaseRepository<Airport, String>,
 	Long countFancyExpression(@Param("projectIds") List<String> projectIds, @Param("planIds") List<String> planIds,
 			@Param("active") Boolean active);
 
+	@Query("SELECT 1 FROM `#{#n1ql.bucket}` WHERE 0 = 1" )
+	Long countBad();
+
+	@Query("SELECT count(*) FROM `#{#n1ql.bucket}`" )
+	Long countGood();
+
 	@ScanConsistency(query = QueryScanConsistency.REQUEST_PLUS)
 	Page<Airport> findAllByIataNot(String iata, Pageable pageable);
 

src/test/java/org/springframework/data/couchbase/repository/CouchbaseRepositoryQueryIntegrationTests.java

@@ -50,6 +50,7 @@ import org.springframework.dao.DataRetrievalFailureException;
 import org.springframework.data.auditing.DateTimeProvider;
 import org.springframework.data.couchbase.CouchbaseClientFactory;
 import org.springframework.data.couchbase.config.AbstractCouchbaseConfiguration;
+import org.springframework.data.couchbase.core.CouchbaseQueryExecutionException;
 import org.springframework.data.couchbase.core.CouchbaseTemplate;
 import org.springframework.data.couchbase.core.RemoveResult;
 import org.springframework.data.couchbase.core.query.N1QLExpression;
@@ -474,6 +475,16 @@ public class CouchbaseRepositoryQueryIntegrationTests extends ClusterAwareIntegr
 		}
 	}
 
+	@Test 
+	void badCount(){
+		assertThrows(CouchbaseQueryExecutionException.class, () -> airportRepository.countBad());
+	}
+
+	@Test 
+	void goodCount(){
+		airportRepository.countGood();
+	}
+
 	@Test
 	void threadSafeParametersTest() throws Exception {
 		String[] iatas = { "JFK", "IAD", "SFO", "SJC", "SEA", "LAX", "PHX" };