Update the route to return 404 if an model does not exist.

src/main/java/space/kklochko/spring_rest_example/controllers/DepartmentController.java

@@ -2,6 +2,7 @@ package space.kklochko.spring_rest_example.controllers;
 
 import jakarta.persistence.EntityManager;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.*;
 import space.kklochko.spring_rest_example.db.repositories.DepartmentRepository;
@@ -37,8 +38,13 @@ public class DepartmentController {
 
     @GetMapping("/{id}")
     @ResponseBody
-    public Department get(@PathVariable UUID id) {
-        return departmentRepository.read(id);
+    public ResponseEntity<?> get(@PathVariable UUID id) {
+        Department department = departmentRepository.read(id);
+
+        if(department == null)
+            return new ResponseEntity<>("Department not found", HttpStatus.NOT_FOUND);
+
+        return new ResponseEntity<>(department, HttpStatus.OK);
     }
 
     @GetMapping

src/main/java/space/kklochko/spring_rest_example/controllers/IndicatorController.java

@@ -3,6 +3,7 @@ package space.kklochko.spring_rest_example.controllers;
 import jakarta.persistence.Entity;
 import jakarta.persistence.EntityManager;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.*;
 import space.kklochko.spring_rest_example.db.repositories.IndicatorRepository;
@@ -40,8 +41,13 @@ public class IndicatorController {
 
     @GetMapping("/{id}")
     @ResponseBody
-    public Indicator get(@PathVariable UUID id) {
-        return indicatorRepository.read(id);
+    public ResponseEntity<?> get(@PathVariable UUID id) {
+        Indicator indicator = indicatorRepository.read(id);
+
+        if(indicator == null)
+            return new ResponseEntity<>("Indicator not found", HttpStatus.NOT_FOUND);
+
+        return new ResponseEntity<>(indicator, HttpStatus.OK);
     }
 
     @GetMapping

src/main/java/space/kklochko/spring_rest_example/controllers/PatientController.java

@@ -2,6 +2,7 @@ package space.kklochko.spring_rest_example.controllers;
 
 import jakarta.persistence.EntityManager;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.annotation.*;
 import space.kklochko.spring_rest_example.db.repositories.PatientRepository;
@@ -37,8 +38,13 @@ public class PatientController {
 
     @GetMapping("/{id}")
     @ResponseBody
-    public Patient get(@PathVariable UUID id) {
-        return patientRepository.read(id);
+    public ResponseEntity<?> get(@PathVariable UUID id) {
+        Patient patient = patientRepository.read(id);
+
+        if(patient == null)
+            return new ResponseEntity<>("Patient not found", HttpStatus.NOT_FOUND);
+
+        return new ResponseEntity<>(patient, HttpStatus.OK);
     }
 
     @GetMapping