Fix order by rendering for queries containing UNION

Make sure to append space after order by clause and fix alias detection for wrapped sub select.
Also make sure to ignore alias used in subselect so they do not conflict with root ones.

Author: christophstrobl

spring-data-jpa/src/main/java/org/springframework/data/jpa/repository/query/HqlSortedQueryTransformer.java

@@ -100,7 +100,7 @@ public QueryTokenStream visitJoinPath(HqlParser.JoinPathContext ctx) {
 
 		QueryTokenStream tokens = super.visitJoinPath(ctx);
 
-		if (ctx.variable() != null) {
+		if (ctx.variable() != null  && !isSubquery(ctx)) {
 			transformerSupport.registerAlias(tokens.getLast());
 		}
 
@@ -112,7 +112,7 @@ public QueryTokenStream visitJoinSubquery(HqlParser.JoinSubqueryContext ctx) {
 
 		QueryTokenStream tokens = super.visitJoinSubquery(ctx);
 
-		if (ctx.variable() != null && !tokens.isEmpty()) {
+		if (ctx.variable() != null && !tokens.isEmpty()  && !isSubquery(ctx)) {
 			transformerSupport.registerAlias(tokens.getLast());
 		}
 
@@ -124,7 +124,7 @@ public QueryTokenStream visitVariable(HqlParser.VariableContext ctx) {
 
 		QueryTokenStream tokens = super.visitVariable(ctx);
 
-		if (ctx.identifier() != null && !tokens.isEmpty()) {
+		if (ctx.identifier() != null && !tokens.isEmpty()  && !isSubquery(ctx)) {
 			transformerSupport.registerAlias(tokens.getLast());
 		}
 

spring-data-jpa/src/test/java/org/springframework/data/jpa/repository/query/HqlQueryTransformerTests.java

@@ -17,18 +17,22 @@
 
 import static org.assertj.core.api.Assertions.*;
 
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
 import java.util.stream.Stream;
 
 import org.assertj.core.api.SoftAssertions;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.MethodSource;
+import org.junit.jupiter.params.provider.ValueSource;
 import org.springframework.dao.InvalidDataAccessApiUsageException;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Sort;
 import org.springframework.data.jpa.domain.JpaSort;
 import org.springframework.lang.Nullable;
+import org.springframework.util.StringUtils;
 
 /**
  * Verify that HQL queries are properly transformed through the {@link JpaQueryEnhancer} and the
@@ -1061,6 +1065,40 @@ void createsCountQueryUsingAliasCorrectly() {
 				"select count(distinct a, count(b)) from Employee AS __ GROUP BY n");
 	}
 
+	@Test // GH-3427
+	void sortShouldBeAppendedWithSpacingInCaseOfSetOperator() {
+
+        String source = "SELECT tb FROM Test tb WHERE (tb.type='A') UNION SELECT tb FROM Test tb WHERE (tb.type='B')";
+		String target = createQueryFor(source, Sort.by("Type").ascending());
+
+		assertThat(target).contains(" UNION SELECT ").doesNotContainPattern(Pattern.compile(".*\\SUNION"));
+	}
+
+	@ParameterizedTest // GH-3427
+	@ValueSource(strings = {"", "res"})
+	void sortShouldBeAppendedToSubSelectWithSetOperatorInSubselect(String alias) {
+
+		String prefix = StringUtils.hasText(alias) ? (alias + ".") : "";
+		String source = "SELECT %sname FROM (SELECT c.name as name FROM Category c UNION SELECT t.name as name FROM Tag t)".formatted(prefix);
+		if(StringUtils.hasText(alias)) {
+			source = source + " %s".formatted(alias);
+		}
+
+		String target = createQueryFor(source, Sort.by("name").ascending());
+
+		assertThat(target).contains(" UNION SELECT ").doesNotContainPattern(Pattern.compile(".*\\SUNION"));
+		assertThat(target).endsWith("order by %sname asc".formatted(prefix)).satisfies(it -> {
+			Pattern pattern = Pattern.compile("order by %sname".formatted(prefix));
+			Matcher matcher = pattern.matcher(target);
+			int count = 0;
+			while(matcher.find()) {
+				count++;
+			}
+			assertThat(count).describedAs("Found order by clause more than once in: \n%s", it).isOne();
+		});
+
+	}
+
 	private void assertCountQuery(String originalQuery, String countQuery) {
 		assertThat(createCountQueryFor(originalQuery)).isEqualTo(countQuery);
 	}