Polishing.

Introduce Query.isLimited method to avoid magic numbers.

See #1233
Original pull request: #1233.

spring-data-r2dbc/src/main/java/org/springframework/data/r2dbc/core/R2dbcEntityTemplate.java

@@ -151,8 +151,7 @@ public class R2dbcEntityTemplate implements R2dbcEntityOperations, BeanFactoryAw
 	 * @param databaseClient must not be {@literal null}.
 	 * @since 1.2
 	 */
-	public R2dbcEntityTemplate(DatabaseClient databaseClient,
+	public R2dbcEntityTemplate(DatabaseClient databaseClient, ReactiveDataAccessStrategy strategy) {
-			ReactiveDataAccessStrategy strategy) {
 
 		Assert.notNull(databaseClient, "DatabaseClient must not be null");
 		Assert.notNull(strategy, "ReactiveDataAccessStrategy must not be null");
@@ -421,13 +420,8 @@ public class R2dbcEntityTemplate implements R2dbcEntityOperations, BeanFactoryAw
 	 */
 	@Override
 	public <T> Mono<T> selectOne(Query query, Class<T> entityClass) throws DataAccessException {
-		Query q = query;
+		return doSelect(query.isLimited() ? query : query.limit(2), entityClass, getTableName(entityClass), entityClass,
-		/* If the query has not a defined limit, a limit of 2 is employed
+				RowsFetchSpec::one);
-			to catch cases where the query would yield more than one result. */
-		if (query.getLimit() == -1) {
-			q = query.limit(2);
-		} // else: use the already defined limit.
-		return doSelect(q, entityClass, getTableName(entityClass), entityClass, RowsFetchSpec::one);
 	}
 
 	/*

spring-data-r2dbc/src/test/java/org/springframework/data/r2dbc/core/R2dbcEntityTemplateUnitTests.java

@@ -90,8 +90,7 @@ public class R2dbcEntityTemplateUnitTests {
 
 		MockRowMetadata metadata = MockRowMetadata.builder()
 				.columnMetadata(MockColumnMetadata.builder().name("name").type(R2dbcType.VARCHAR).build()).build();
-		MockResult result = MockResult.builder()
+		MockResult result = MockResult.builder().row(MockRow.builder().identified(0, Long.class, 1L).build()).build();
-				.row(MockRow.builder().identified(0, Long.class, 1L).build()).build();
 
 		recorder.addStubbing(s -> s.startsWith("SELECT"), result);
 
@@ -111,8 +110,7 @@ public class R2dbcEntityTemplateUnitTests {
 
 		MockRowMetadata metadata = MockRowMetadata.builder()
 				.columnMetadata(MockColumnMetadata.builder().name("name").type(R2dbcType.VARCHAR).build()).build();
-		MockResult result = MockResult.builder()
+		MockResult result = MockResult.builder().row(MockRow.builder().identified(0, Object.class, null).build()).build();
-				.row(MockRow.builder().identified(0, Object.class, null).build()).build();
 
 		recorder.addStubbing(s -> s.startsWith("SELECT"), result);
 
@@ -129,8 +127,7 @@ public class R2dbcEntityTemplateUnitTests {
 
 		MockRowMetadata metadata = MockRowMetadata.builder()
 				.columnMetadata(MockColumnMetadata.builder().name("name").type(R2dbcType.VARCHAR).build()).build();
-		MockResult result = MockResult.builder()
+		MockResult result = MockResult.builder().row(MockRow.builder().identified(0, Long.class, 1L).build()).build();
-				.row(MockRow.builder().identified(0, Long.class, 1L).build()).build();
 
 		recorder.addStubbing(s -> s.startsWith("SELECT"), result);
 
@@ -208,7 +205,8 @@ public class R2dbcEntityTemplateUnitTests {
 
 		recorder.addStubbing(s -> s.startsWith("SELECT"), Collections.emptyList());
 
-		entityTemplate.selectOne(Query.query(Criteria.where("name").is("Walter")).sort(Sort.by("name")).limit(1), Person.class) //
+		entityTemplate
+				.selectOne(Query.query(Criteria.where("name").is("Walter")).sort(Sort.by("name")).limit(1), Person.class) //
 				.as(StepVerifier::create) //
 				.verifyComplete();
 

spring-data-relational/src/main/java/org/springframework/data/relational/core/query/Query.java

@@ -41,6 +41,8 @@ import org.springframework.util.Assert;
  */
 public class Query {
 
+	private static final int NO_LIMIT = -1;
+
 	private final @Nullable CriteriaDefinition criteria;
 
 	private final List<SqlIdentifier> columns;
@@ -64,7 +66,7 @@ public class Query {
 	 * @param criteria must not be {@literal null}.
 	 */
 	private Query(@Nullable CriteriaDefinition criteria) {
-		this(criteria, Collections.emptyList(), Sort.unsorted(), -1, -1);
+		this(criteria, Collections.emptyList(), Sort.unsorted(), NO_LIMIT, NO_LIMIT);
 	}
 
 	private Query(@Nullable CriteriaDefinition criteria, List<SqlIdentifier> columns, Sort sort, int limit, long offset) {
@@ -248,6 +250,17 @@ public class Query {
 		return this.limit;
 	}
 
+	/**
+	 * Return whether the query has a limit.
+	 *
+	 * @return {@code true} if a limit is set.
+	 * @see #getLimit()
+	 * @since 3.0
+	 */
+	public boolean isLimited() {
+		return getLimit() != NO_LIMIT;
+	}
+
 	private static void assertNoCaseSort(Sort sort) {
 
 		for (Sort.Order order : sort) {