Remove unnecessary join when filtering on relationship id

Closes #3349

Signed-off-by: Jakub Soltys <jsodpad@gmail.com>

Author: bukajsytlos

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

@@ -88,6 +88,7 @@
  * @author Eduard Dudar
  * @author Yanming Zhou
  * @author Alim Naizabek
+ * @author Jakub Soltys
  */
 public abstract class QueryUtils {
 
@@ -780,6 +781,16 @@ static <T> Expression<T> toExpressionRecursively(From<?, ?> from, PropertyPath p
 			return from.get(segment);
 		}
 
+		boolean isRelationshipId = isRelationshipId(from, property);
+		if (isRelationshipId) {
+			Path<T> relationshipIdPath = from.get(segment);
+			while (property.hasNext()) {
+				property = property.next();
+				relationshipIdPath = relationshipIdPath.get(property.getSegment());
+			}
+			return relationshipIdPath;
+		}
+
 		// get or create the join
 		JoinType joinType = requiresOuterJoin ? JoinType.LEFT : JoinType.INNER;
 		Join<?, ?> join = getOrCreateJoin(from, segment, joinType);
@@ -851,6 +862,24 @@ static boolean requiresOuterJoin(From<?, ?> from, PropertyPath property, boolean
 		return hasRequiredOuterJoin || getAnnotationProperty(attribute, "optional", true);
 	}
 
+	/**
+	 * Checks if this property path is pointing to relationship id.
+	 *
+	 * @param from the {@link From} to check for fetches.
+	 * @param property the property path
+	 * @return whether in a query is relationship id.
+	 */
+    private static boolean isRelationshipId(From<?, ?> from, PropertyPath property) {
+        if (!property.hasNext()) {
+            return false;
+        }
+        Bindable<Object> nextSegmentModel = from.get(property.getSegment()).get(property.next().getSegment()).getModel();
+        if (nextSegmentModel instanceof SingularAttribute<?, ?>) {
+            return ((SingularAttribute<?, ?>) nextSegmentModel).isId();
+        }
+        return false;
+    }
+
 	@SuppressWarnings("unchecked")
 	static <T> T getAnnotationProperty(Attribute<?, ?> attribute, String propertyName, T defaultValue) {
 

spring-data-jpa/src/test/java/org/springframework/data/jpa/domain/sample/ReferencingEmbeddedIdExampleEmployee.java

@@ -0,0 +1,43 @@
+/*
+ * Copyright 2013-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.jpa.domain.sample;
+
+import jakarta.persistence.*;
+
+@Entity
+public class ReferencingEmbeddedIdExampleEmployee {
+
+	@Id private long id;
+
+	@ManyToOne private//
+	EmbeddedIdExampleEmployee employee;
+
+	public long getId() {
+		return id;
+	}
+
+	public void setId(long id) {
+		this.id = id;
+	}
+
+	public EmbeddedIdExampleEmployee getEmployee() {
+		return employee;
+	}
+
+	public void setEmployee(EmbeddedIdExampleEmployee employee) {
+		this.employee = employee;
+	}
+}

spring-data-jpa/src/test/java/org/springframework/data/jpa/domain/sample/ReferencingIdClassExampleEmployee.java

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2013-2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.springframework.data.jpa.domain.sample;
+
+import jakarta.persistence.*;
+
+@Entity
+public class ReferencingIdClassExampleEmployee {
+
+	@Id private long id;
+	@ManyToOne private IdClassExampleEmployee employee;
+
+	public long getId() {
+		return id;
+	}
+
+	public void setId(long id) {
+		this.id = id;
+	}
+
+	public IdClassExampleEmployee getEmployee() {
+		return employee;
+	}
+
+	public void setEmployee(IdClassExampleEmployee employee) {
+		this.employee = employee;
+	}
+}

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

@@ -52,11 +52,7 @@
 
 import org.springframework.data.domain.Sort;
 import org.springframework.data.domain.Sort.Direction;
-import org.springframework.data.jpa.domain.sample.Category;
-import org.springframework.data.jpa.domain.sample.Invoice;
-import org.springframework.data.jpa.domain.sample.InvoiceItem;
-import org.springframework.data.jpa.domain.sample.Order;
-import org.springframework.data.jpa.domain.sample.User;
+import org.springframework.data.jpa.domain.sample.*;
 import org.springframework.data.jpa.infrastructure.HibernateTestUtils;
 import org.springframework.data.mapping.PropertyPath;
 import org.springframework.test.context.ContextConfiguration;
@@ -71,6 +67,7 @@
  * @author Patrice Blanchardie
  * @author Diego Krupitza
  * @author Krzysztof Krason
+ * @author Jakub Soltys
  */
 @ExtendWith(SpringExtension.class)
 @ContextConfiguration("classpath:infrastructure.xml")
@@ -387,6 +384,45 @@ void demonstrateDifferentBehaviorOfGetJoin() {
 		assertThat(root.getJoins()).hasSize(getNumberOfJoinsAfterCreatingAPath());
 	}
 
+	@Test // GH-3349
+	void doesNotCreateJoinForRelationshipSimpleId() {
+
+		CriteriaBuilder builder = em.getCriteriaBuilder();
+		CriteriaQuery<User> query = builder.createQuery(User.class);
+		Root<User> from = query.from(User.class);
+
+        QueryUtils.toExpressionRecursively(from, PropertyPath.from("manager.id", User.class));
+
+		assertThat(from.getFetches()).hasSize(0);
+		assertThat(from.getJoins()).hasSize(0);
+	}
+
+	@Test // GH-3349
+	void doesNotCreateJoinForRelationshipEmbeddedId() {
+
+		CriteriaBuilder builder = em.getCriteriaBuilder();
+		CriteriaQuery<ReferencingEmbeddedIdExampleEmployee> query = builder.createQuery(ReferencingEmbeddedIdExampleEmployee.class);
+		Root<ReferencingEmbeddedIdExampleEmployee> from = query.from(ReferencingEmbeddedIdExampleEmployee.class);
+
+        QueryUtils.toExpressionRecursively(from, PropertyPath.from("employee.employeePk.employeeId", ReferencingEmbeddedIdExampleEmployee.class));
+
+		assertThat(from.getFetches()).hasSize(0);
+		assertThat(from.getJoins()).hasSize(0);
+	}
+
+	@Test // GH-3349
+	void doesNotCreateJoinForRelationshipIdClass() {
+
+		CriteriaBuilder builder = em.getCriteriaBuilder();
+		CriteriaQuery<ReferencingIdClassExampleEmployee> query = builder.createQuery(ReferencingIdClassExampleEmployee.class);
+		Root<ReferencingIdClassExampleEmployee> from = query.from(ReferencingIdClassExampleEmployee.class);
+
+		QueryUtils.toExpressionRecursively(from, PropertyPath.from("employee.empId", ReferencingIdClassExampleEmployee.class));
+
+		assertThat(from.getFetches()).hasSize(0);
+		assertThat(from.getJoins()).hasSize(0);
+	}
+
 	int getNumberOfJoinsAfterCreatingAPath() {
 		return 0;
 	}

spring-data-jpa/src/test/resources/META-INF/persistence.xml

@@ -27,9 +27,11 @@
 		<class>org.springframework.data.jpa.domain.sample.EmbeddedIdExampleEmployeePK</class>
 		<class>org.springframework.data.jpa.domain.sample.EmbeddedIdExampleEmployee</class>
 		<class>org.springframework.data.jpa.domain.sample.EmbeddedIdExampleDepartment</class>
+		<class>org.springframework.data.jpa.domain.sample.ReferencingEmbeddedIdExampleEmployee</class>
 		<class>org.springframework.data.jpa.domain.sample.EmployeeWithName</class>
 		<class>org.springframework.data.jpa.domain.sample.IdClassExampleEmployee</class>
 		<class>org.springframework.data.jpa.domain.sample.IdClassExampleDepartment</class>
+		<class>org.springframework.data.jpa.domain.sample.ReferencingIdClassExampleEmployee</class>
 		<class>org.springframework.data.jpa.domain.sample.Invoice</class>
 		<class>org.springframework.data.jpa.domain.sample.InvoiceItem</class>
 		<class>org.springframework.data.jpa.domain.sample.Item</class>