Extend UserRoleRepository methods: add findByCompositeId

Signed-off-by: Pekka Helenius <fincer89@hotmail.com>

bookstore/src/main/java/com/fjordtek/bookstore/model/auth/UserRoleRepository.java

@@ -19,5 +19,5 @@ import org.springframework.data.rest.core.annotation.RepositoryRestResource;
 		itemResourceRel = "userroles",
 		exported        = true
 		)
-public interface UserRoleRepository extends CrudRepository<UserRole, Long> {
+public interface UserRoleRepository extends CrudRepository<UserRole, Long>, UserRoleRepositoryCustom {
 }

bookstore/src/main/java/com/fjordtek/bookstore/model/auth/UserRoleRepositoryCustom.java

@@ -0,0 +1,14 @@
+//Pekka Helenius <fincer89@hotmail.com>, Fjordtek 2020
+
+package com.fjordtek.bookstore.model.auth;
+
+/**
+*
+* This interface defines additional methods for UserRoleRepository.
+*
+* @author Pekka Helenius
+*/
+
+public interface UserRoleRepositoryCustom {
+	UserRole findByCompositeId(Long userId, Long roleId);
+}

bookstore/src/main/java/com/fjordtek/bookstore/model/auth/UserRoleRepositoryImpl.java

@@ -0,0 +1,48 @@
+//Pekka Helenius <fincer89@hotmail.com>, Fjordtek 2020
+
+package com.fjordtek.bookstore.model.auth;
+
+import javax.persistence.EntityManager;
+import javax.persistence.PersistenceContext;
+import javax.persistence.TypedQuery;
+
+import org.springframework.transaction.annotation.Transactional;
+
+/**
+ *
+ * This class implements methods defined in UserRoleRepositoryCustom interface.
+ *
+ * @author Pekka Helenius
+ */
+
+@Transactional
+public class UserRoleRepositoryImpl implements UserRoleRepositoryCustom {
+
+	@PersistenceContext
+	EntityManager entityManager;
+
+	/*
+	 * Find unique USER_ROLE entry by user & role IDs
+	 */
+
+	@Override
+	public UserRole findByCompositeId(Long userId, Long roleId) {
+
+		TypedQuery<UserRole> query = entityManager.createQuery(
+				"SELECT i FROM UserRole i" +
+				" WHERE user_id = :user_id" +
+				" AND role_id   = :role_id",
+				UserRole.class
+				);
+
+		query.setParameter("user_id", userId);
+		query.setParameter("role_id", roleId);
+
+		try {
+			return query.getResultList().get(0);
+		} catch (IndexOutOfBoundsException ignored) {
+			return null;
+		}
+	}
+
+}