From 487001195db1d5c45152bf8e5b188d6aae3f4c61 Mon Sep 17 00:00:00 2001
From: Alexander <alexraddan@gmail.com>
Date: Mon, 19 Aug 2024 13:34:29 +0300
Subject: [PATCH] refactor: extract common entity retrieval logic to a private
 helper method

---
 .../petclinic/service/ClinicServiceImpl.java  | 69 ++++---------------
 1 file changed, 15 insertions(+), 54 deletions(-)

diff --git a/src/main/java/org/springframework/samples/petclinic/service/ClinicServiceImpl.java b/src/main/java/org/springframework/samples/petclinic/service/ClinicServiceImpl.java
index 27e59ff26..baf81184e 100644
--- a/src/main/java/org/springframework/samples/petclinic/service/ClinicServiceImpl.java
+++ b/src/main/java/org/springframework/samples/petclinic/service/ClinicServiceImpl.java
@@ -24,10 +24,10 @@
 import org.springframework.stereotype.Service;
 import org.springframework.transaction.annotation.Transactional;
 
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
 import java.util.Set;
+import java.util.function.Supplier;
 
 /**
  * Mostly used as a facade for all Petclinic controllers
@@ -77,14 +77,7 @@ public void deletePet(Pet pet) throws DataAccessException {
     @Override
     @Transactional(readOnly = true)
     public Visit findVisitById(int visitId) throws DataAccessException {
-        Visit visit = null;
-        try {
-            visit = visitRepository.findById(visitId);
-        } catch (ObjectRetrievalFailureException | EmptyResultDataAccessException e) {
-            // just ignore not found exceptions for Jdbc/Jpa realization
-            return null;
-        }
-        return visit;
+        return findEntityById(() -> visitRepository.findById(visitId));
     }
 
     @Override
@@ -102,14 +95,7 @@ public void deleteVisit(Visit visit) throws DataAccessException {
     @Override
     @Transactional(readOnly = true)
     public Vet findVetById(int id) throws DataAccessException {
-        Vet vet = null;
-        try {
-            vet = vetRepository.findById(id);
-        } catch (ObjectRetrievalFailureException | EmptyResultDataAccessException e) {
-            // just ignore not found exceptions for Jdbc/Jpa realization
-            return null;
-        }
-        return vet;
+        return findEntityById(() -> vetRepository.findById(id));
     }
 
     @Override
@@ -145,14 +131,7 @@ public void deleteOwner(Owner owner) throws DataAccessException {
     @Override
     @Transactional(readOnly = true)
     public PetType findPetTypeById(int petTypeId) {
-        PetType petType = null;
-        try {
-            petType = petTypeRepository.findById(petTypeId);
-        } catch (ObjectRetrievalFailureException | EmptyResultDataAccessException e) {
-            // just ignore not found exceptions for Jdbc/Jpa realization
-            return null;
-        }
-        return petType;
+        return findEntityById(() -> petTypeRepository.findById(petTypeId));
     }
 
     @Override
@@ -176,14 +155,7 @@ public void deletePetType(PetType petType) throws DataAccessException {
     @Override
     @Transactional(readOnly = true)
     public Specialty findSpecialtyById(int specialtyId) {
-        Specialty specialty = null;
-        try {
-            specialty = specialtyRepository.findById(specialtyId);
-        } catch (ObjectRetrievalFailureException | EmptyResultDataAccessException e) {
-            // just ignore not found exceptions for Jdbc/Jpa realization
-            return null;
-        }
-        return specialty;
+        return findEntityById(() -> specialtyRepository.findById(specialtyId));
     }
 
     @Override
@@ -213,27 +185,13 @@ public Collection<PetType> findPetTypes() throws DataAccessException {
     @Override
     @Transactional(readOnly = true)
     public Owner findOwnerById(int id) throws DataAccessException {
-        Owner owner = null;
-        try {
-            owner = ownerRepository.findById(id);
-        } catch (ObjectRetrievalFailureException | EmptyResultDataAccessException e) {
-            // just ignore not found exceptions for Jdbc/Jpa realization
-            return null;
-        }
-        return owner;
+        return findEntityById(() -> ownerRepository.findById(id));
     }
 
     @Override
     @Transactional(readOnly = true)
     public Pet findPetById(int id) throws DataAccessException {
-        Pet pet = null;
-        try {
-            pet = petRepository.findById(id);
-        } catch (ObjectRetrievalFailureException | EmptyResultDataAccessException e) {
-            // just ignore not found exceptions for Jdbc/Jpa realization
-            return null;
-        }
-        return pet;
+        return findEntityById(() -> petRepository.findById(id));
     }
 
     @Override
@@ -277,13 +235,16 @@ public Collection<Visit> findVisitsByPetId(int petId) {
     @Override
     @Transactional(readOnly = true)
     public List<Specialty> findSpecialtiesByNameIn(Set<String> names) {
-        List<Specialty> specialties = new ArrayList<>();
+        return findEntityById(() -> specialtyRepository.findSpecialtiesByNameIn(names));
+    }
+
+    private <T> T findEntityById(Supplier<T> supplier) {
         try {
-            specialties = specialtyRepository.findSpecialtiesByNameIn(names);
+            return supplier.get();
         } catch (ObjectRetrievalFailureException | EmptyResultDataAccessException e) {
-            // just ignore not found exceptions for Jdbc/Jpa realization
-            return specialties;
+            // Just ignore not found exceptions for Jdbc/Jpa realization
+            return null;
         }
-        return specialties;
     }
+
 }