Delay count query derivation.

We now delay the count query creation to the actual time when we need the count query to avoid query creation of invalid queries (e.g. count queries for DELETE or UPDATE statements).

See #2812

Author: mp911de

src/main/java/org/springframework/data/jpa/repository/query/AbstractStringBasedJpaQuery.java

@@ -21,6 +21,7 @@
 import org.springframework.data.repository.query.QueryMethodEvaluationContextProvider;
 import org.springframework.data.repository.query.ResultProcessor;
 import org.springframework.data.repository.query.ReturnedType;
+import org.springframework.data.util.Lazy;
 import org.springframework.expression.spel.standard.SpelExpressionParser;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
@@ -39,7 +40,7 @@
 abstract class AbstractStringBasedJpaQuery extends AbstractJpaQuery {
 
 	private final DeclaredQuery query;
-	private final DeclaredQuery countQuery;
+	private final Lazy<DeclaredQuery> countQuery;
 	private final QueryMethodEvaluationContextProvider evaluationContextProvider;
 	private final SpelExpressionParser parser;
 	private final QueryParameterSetter.QueryMetadataCache metadataCache = new QueryParameterSetter.QueryMetadataCache();
@@ -69,9 +70,10 @@ public AbstractStringBasedJpaQuery(JpaQueryMethod method, EntityManager em, Stri
 		this.query = new ExpressionBasedStringQuery(queryString, method.getEntityInformation(), parser,
 				method.isNativeQuery());
 
-		DeclaredQuery countQuery = query.deriveCountQuery(countQueryString, method.getCountQueryProjection());
-		this.countQuery = ExpressionBasedStringQuery.from(countQuery, method.getEntityInformation(), parser,
-				method.isNativeQuery());
+		this.countQuery = Lazy.of(() -> {
+			DeclaredQuery countQuery = query.deriveCountQuery(countQueryString, method.getCountQueryProjection());
+			return ExpressionBasedStringQuery.from(countQuery, method.getEntityInformation(), parser, method.isNativeQuery());
+		});
 
 		this.parser = parser;
 
@@ -117,7 +119,7 @@ protected ParameterBinder createBinder() {
 	@Override
 	protected Query doCreateCountQuery(JpaParametersParameterAccessor accessor) {
 
-		String queryString = countQuery.getQueryString();
+		String queryString = countQuery.get().getQueryString();
 		EntityManager em = getEntityManager();
 
 		Query query = getQueryMethod().isNativeQuery() //
@@ -142,7 +144,7 @@ public DeclaredQuery getQuery() {
 	 * @return the countQuery
 	 */
 	public DeclaredQuery getCountQuery() {
-		return countQuery;
+		return countQuery.get();
 	}
 
 	/**