refacto error handling & add locale validation mechanism

TODO.md

@@ -0,0 +1,37 @@
+# TODO List API rest-api-assignment b2boost
+Date : 23-24 nov 2021
+
+- [x] 1. The endpoint will return custom error JSON messages in the payload,  additionally to the standard HTTP response codes similar to this one:
+
+   ```
+  {
+    "code": 404,
+    "message": "Partner with id 1 not found!"
+  }
+   ```
+
+- [x] 2. The application will be cleanly layered, by separating control and  business logic. For instance, the controller of the endpoint will not  contain any business logic, and will limit itself to
+
+  - marshalling data from the http layer to the service layer
+  - reporting error conditions in the response
+  - marshalling results back to the http layer, including custom errors
+
+- [x] 3. The service layer will be transactional and encapsulate all validation and database interactions
+
+- [x] 4. The data layer will be implemented by using a data repository service
+
+- [x] 5. The application can run with an embedded in-memory database
+
+- [ ] 6. The application will have a health check endpoint
+
+- [ ] 7. The application will have suitable functional tests, checking real http functionality
+
+- [x] 8. No authentication/security necessary
+
+- [ ] This document will contain the specification of the REST endpoint, with data definition and error payload specification.
+
+You should document how to
+
+- [ ] Run the test suite
+- [ ] Run application
+- [ ] Optionally, a commentary on how you would deploy it (not necessary to implement this)

src/main/java/com/example/apispringgradleb2boost/controller/PartnerController.java

@@ -7,14 +7,12 @@ import com.example.apispringgradleb2boost.service.PartnerService;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.repository.query.Param;
 import org.springframework.http.HttpStatus;
-import org.springframework.http.MediaType;
 import org.springframework.web.bind.annotation.*;
 
 import com.google.gson.Gson;
 
 import javax.servlet.http.HttpServletResponse;
 import java.io.IOException;
-import java.io.PrintWriter;
 import java.util.Optional;
 
 @RestController
@@ -44,14 +42,14 @@ public class PartnerController {
      * @return A Partner object
      */
     @GetMapping("/partner/{id}")
-    public Partner getPartnerById(@PathVariable("id") final Long Id, HttpServletResponse response) throws IOException {
+    public Partner getPartnerById(@PathVariable("id") final Long Id, HttpServletResponse response) throws CustomError {
 
         Optional<Partner> partner = partnerService.getPartnerById(Id);
         if (partner.isPresent()) {
             return partner.get();
         } else {
             // Error handling when !partner.isPresent()
-            handlePartnerResourceIsNotPresentReturnNotFound(Id, response);
+            handlePartnerResourceIsNotPresentReturnNotFound(Id);
             return null;
         }
     }
@@ -77,32 +75,13 @@ public class PartnerController {
      */
     @PutMapping("/partner/{id}")
     public Partner updatePartner(@PathVariable("id") final Long Id, @RequestBody Partner partner,
-                                 HttpServletResponse response) throws IOException {
+                                 HttpServletResponse response) throws CustomError {
 
         Optional<Partner> p = partnerService.getPartnerById(Id);
         if (p.isPresent()) {
-            Partner currentPartner = p.get();
-
-            String name = partner.getName();
-            if (name != null) {
-                currentPartner.setName(name);
-            }
-            String reference = partner.getReference();
-            if (reference != null) {
-                currentPartner.setReference(reference);
-            }
-            String locale = partner.getLocale();
-            if (locale != null) {
-                currentPartner.setLocale(locale);
-            }
-            String expirationTime = partner.getExpirationTime();
-            if (expirationTime != null) {
-                currentPartner.setExpirationTime(expirationTime);
-            }
-            partnerService.savePartner(currentPartner);
-            return currentPartner;
+            return partnerService.updatePartner(partner, p);
         } else {
-            handlePartnerResourceIsNotPresentReturnNotFound(Id, response);
+            handlePartnerResourceIsNotPresentReturnNotFound(Id);
             return null;
         }
     }
@@ -114,35 +93,28 @@ public class PartnerController {
      * @param Id - The id of the partner to delete
      */
     @DeleteMapping("/partner/{id}")
-    public void deletePartner(@PathVariable("id") final Long Id, HttpServletResponse response) throws IOException {
+    public void deletePartner(@PathVariable("id") final Long Id, HttpServletResponse response) throws CustomError {
         Optional<Partner> partner = partnerService.getPartnerById(Id);
         if (partner.isPresent()) {
             partnerService.deletePartner(Id);
         } else {
-            handlePartnerResourceIsNotPresentReturnNotFound(Id, response);
+            handlePartnerResourceIsNotPresentReturnNotFound(Id);
         }
 
     }
 
     /**
-     * Partner not found handling - Extraction of duplicated code for
+     * Partner not found handling - Extraction of duplicated code when !partner.isPresent()
      *
      * @param Id
-     * @param response
-     * @throws IOException
+     * @throws CustomError
      */
-    private void handlePartnerResourceIsNotPresentReturnNotFound(@PathVariable("id") Long Id, HttpServletResponse response) throws IOException {
+    private void handlePartnerResourceIsNotPresentReturnNotFound(final Long Id) throws CustomError {
         // Error handling when !partner.isPresent()
-        response.setStatus(HttpStatus.NOT_FOUND.value());
-        response.setContentType(String.valueOf(MediaType.APPLICATION_JSON));
-        response.setCharacterEncoding("UTF-8");
-
-        PrintWriter out = response.getWriter();
-        out.print(new Gson().toJson(
+        throw new CustomError(HttpStatus.NOT_FOUND.value(), new Gson().toJson(
                 new CustomError(HttpStatus.NOT_FOUND.value(),
                         String.format("Partner with id %d not found!", Id))
         ));
-        out.flush();
     }
 
 }

src/main/java/com/example/apispringgradleb2boost/exceptionhandling/CustomError.java

@@ -1,16 +1,39 @@
 package com.example.apispringgradleb2boost.exceptionhandling;
 
+import com.google.gson.Gson;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
 import lombok.Data;
+import lombok.EqualsAndHashCode;
 
 @Data
-public class CustomError {
+@EqualsAndHashCode(callSuper = true)
+public class CustomError extends RuntimeException {
 
-    private int code;
-    private String message;
+    private final int code;
+    private final String message;
 
-    public CustomError(int code, String message) {
+    public CustomError(int code, final String message) {
         this.code = code;
         this.message = message;
     }
 
+    /**
+     * Overriding getMessage from RuntimeException to avoid printing stackTrace and suppressedExceptions as for ex :
+     * {
+     *     "code": 404,
+     *     "message": "No handler found for GET /partnersdf",
+     *     "stackTrace": [],
+     *     "suppressedExceptions": []
+     * }
+     * @return overrideMessage
+     * */
+    @Override
+    public String getMessage() {
+        Gson gson = new Gson();
+        JsonObject body = gson.fromJson(message, JsonObject.class);
+        JsonElement extractedCode = body.get("code");
+        JsonElement extractedMessage = body.get("message");
+        return "{\"code\":" + extractedCode + ", \"message\": " + extractedMessage + "}";
+    }
 }

src/main/java/com/example/apispringgradleb2boost/exceptionhandling/GeneralExceptionHandler.java

@@ -1,7 +1,9 @@
 package com.example.apispringgradleb2boost.exceptionhandling;
 
+import com.google.gson.Gson;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
 import org.springframework.web.bind.MethodArgumentNotValidException;
 import org.springframework.web.bind.annotation.ControllerAdvice;
@@ -15,8 +17,22 @@ public class GeneralExceptionHandler extends ResponseEntityExceptionHandler {
 
     @ExceptionHandler({Exception.class})
     public ResponseEntity<Object> handleAll(Exception ex, WebRequest request) {
-        CustomError customError = new CustomError(HttpStatus.INTERNAL_SERVER_ERROR.value(), ex.getLocalizedMessage());
-        return new ResponseEntity<Object>(customError, new HttpHeaders(), customError.getCode());
+
+        HttpHeaders headers = new HttpHeaders();
+        headers.setContentType(MediaType.APPLICATION_JSON);
+        CustomError customError = new CustomError(HttpStatus.INTERNAL_SERVER_ERROR.value(), new Gson().toJson(
+                new CustomError(HttpStatus.INTERNAL_SERVER_ERROR.value(),
+                        ex.getLocalizedMessage())
+        ));
+        return new ResponseEntity<Object>(customError.getMessage(), headers, customError.getCode());
+    }
+
+    @ExceptionHandler({CustomError.class})
+    public ResponseEntity<Object> handleException(CustomError customError) {
+        // log exception
+        HttpHeaders headers = new HttpHeaders();
+        headers.setContentType(MediaType.APPLICATION_JSON);
+        return new ResponseEntity<Object>(customError.getMessage(), headers, customError.getCode());
     }
 
     @Override
@@ -25,15 +41,23 @@ public class GeneralExceptionHandler extends ResponseEntityExceptionHandler {
                                                                   HttpStatus status,
                                                                   WebRequest request) {
 
-        CustomError customError = new CustomError(HttpStatus.BAD_REQUEST.value(), ex.getLocalizedMessage());
-        return handleExceptionInternal(ex, customError, headers, HttpStatus.valueOf(customError.getCode()), request);
+        headers.setContentType(MediaType.APPLICATION_JSON);
+        CustomError customError = new CustomError(HttpStatus.BAD_REQUEST.value(), new Gson().toJson(
+                new CustomError(HttpStatus.BAD_REQUEST.value(),
+                        ex.getLocalizedMessage())
+        ));
+        return handleExceptionInternal(ex, customError.getMessage(), headers, HttpStatus.valueOf(customError.getCode()), request);
     }
 
     @Override
     protected ResponseEntity<Object> handleNoHandlerFoundException(
             NoHandlerFoundException ex, HttpHeaders headers, HttpStatus status, WebRequest request) {
 
-        CustomError customError = new CustomError(HttpStatus.NOT_FOUND.value(), ex.getLocalizedMessage());
-        return new ResponseEntity<Object>(customError, new HttpHeaders(), customError.getCode());
+        headers.setContentType(MediaType.APPLICATION_JSON);
+        CustomError customError = new CustomError(HttpStatus.NOT_FOUND.value(), new Gson().toJson(
+                new CustomError(HttpStatus.NOT_FOUND.value(),
+                        ex.getLocalizedMessage())
+        ));
+        return new ResponseEntity<Object>(customError.getMessage(), headers, customError.getCode());
     }
 }

src/main/java/com/example/apispringgradleb2boost/model/Partner.java

@@ -3,6 +3,8 @@ package com.example.apispringgradleb2boost.model;
 import lombok.Data;
 
 import javax.persistence.*;
+import java.util.Locale;
+
 
 @Data
 @Entity
@@ -15,11 +17,13 @@ public class Partner {
     @Column(name = "company_name")
     private String name;
 
-    @Column(name = "ref", unique=true)
+    @Column(name = "ref", unique = true)
     private String reference;
 
-    private String locale;
+    private Locale locale;
 
     @Column(name = "expires")
     private String expirationTime;
+
+
 }

src/main/java/com/example/apispringgradleb2boost/service/PartnerService.java

@@ -1,15 +1,21 @@
 package com.example.apispringgradleb2boost.service;
 
+import com.example.apispringgradleb2boost.exceptionhandling.CustomError;
 import com.example.apispringgradleb2boost.model.Partner;
 import com.example.apispringgradleb2boost.repository.PartnerRepository;
+import com.google.gson.Gson;
 import lombok.Data;
+
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.data.domain.PageRequest;
 import org.springframework.data.domain.Pageable;
+import org.springframework.http.HttpStatus;
 import org.springframework.stereotype.Service;
 import org.springframework.validation.annotation.Validated;
 
 import javax.validation.constraints.Min;
+import java.util.Arrays;
+import java.util.Locale;
 import java.util.Optional;
 
 @Data
@@ -34,10 +40,54 @@ public class PartnerService {
     }
 
     public Partner savePartner(Partner partner) {
+        if (localeIsValid(partner.getLocale())) {
             return partnerRepository.save(partner);
+        } else {
+            return null;
+        }
+    }
+
+    public Partner updatePartner(Partner partner, Optional<Partner> p) {
+        Partner currentPartner = p.get();
+
+        String name = partner.getName();
+        if (name != null) {
+            currentPartner.setName(name);
+        }
+        String reference = partner.getReference();
+        if (reference != null) {
+            currentPartner.setReference(reference);
+        }
+        Locale locale = partner.getLocale();
+        if (localeIsValid(locale)) {
+            currentPartner.setLocale(locale);
+        }
+        String expirationTime = partner.getExpirationTime();
+        if (expirationTime != null) {
+            currentPartner.setExpirationTime(expirationTime);
+        }
+        savePartner(currentPartner);
+        return currentPartner;
     }
 
     public void deletePartner(@Min(0) final Long Id) {
         partnerRepository.deleteById(Id);
     }
+
+    /**
+     * Check whether the locale object is valid locale if not throw custom error
+     *
+     * @param locale
+     * @return Boolean
+     */
+    public Boolean localeIsValid(Locale locale) {
+        if (Arrays.asList(Locale.getAvailableLocales()).contains(locale)) {
+            return true;
+        } else {
+            throw new CustomError(HttpStatus.BAD_REQUEST.value(), new Gson().toJson(
+                    new CustomError(HttpStatus.BAD_REQUEST.value(),
+                            String.format("Locale %s is an invalid Locale!", locale.toString()))
+            ));
+        }
+    }
 }