Small changes to refactor the solution

jabrena · jabrena · commit 5677f80c0303 · 2025-06-20T18:22:23.000+02:00
diff --git a/examples/spring-boot-demo/implementation/src/main/java/com/example/demo/controller/FilmController.java b/examples/spring-boot-demo/implementation/src/main/java/com/example/demo/controller/FilmController.java
@@ -7,6 +7,7 @@
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.http.ResponseEntity;
 import org.springframework.http.HttpStatus;
+import org.springframework.http.ProblemDetail;
 import com.example.demo.service.FilmService;
 import com.example.demo.dto.FilmResponse;
 
@@ -18,7 +19,11 @@
 import io.swagger.v3.oas.annotations.media.Content;
 import io.swagger.v3.oas.annotations.media.Schema;
 
+import jakarta.servlet.http.HttpServletRequest;
+import java.net.URI;
+import java.time.Instant;
 import java.util.Map;
+import java.util.Objects;
 import java.util.HashMap;
 import java.util.List;
 
@@ -65,8 +70,8 @@ public FilmController(FilmService filmService) {
      * Retrieves films from the Sakila database, optionally filtered by starting letter.
      * 
      * @param startsWith Optional parameter to filter films by starting letter (single character A-Z)
-     * @return JSON response containing films array, count, and filter information
-     * @throws IllegalArgumentException if startsWith parameter is invalid (not a single letter)
+     * @param request HttpServletRequest for building error responses
+     * @return JSON response containing films array, count, and filter information or error response
      */
     @Operation(
         summary = "Query films by starting letter",
@@ -78,8 +83,6 @@ public FilmController(FilmService filmService) {
             
             **Expected Results**:
             - Letter "A": 46 films
-            - Letter "B": 54 films  
-            - Letter "C": 58 films
             """,
         operationId = "getFilmsByStartingLetter"
     )
@@ -110,18 +113,22 @@ public FilmController(FilmService filmService) {
         )
     })
     @GetMapping("/films")
-    public ResponseEntity<FilmResponse> getFilms(
+    public ResponseEntity<?> getFilms(
             @Parameter(
                 name = "startsWith",
                 description = "Filter films by starting letter (case-insensitive, single character A-Z)",
                 example = "A",
                 schema = @Schema(type = "string", pattern = "^[A-Za-z]$")
             )
-            @RequestParam(required = false) String startsWith) {
+            @RequestParam(required = false) String startsWith,
+            HttpServletRequest request) {
         
         // Task 4.4: Implement parameter validation logic (single letter, not empty)
-        if (startsWith != null) {
-            validateStartsWithParameter(startsWith);
+        if (Objects.nonNull(startsWith)) {
+            ValidationResult validationResult = validateStartsWithParameter(startsWith);
+            if (!validationResult.valid()) {
+                return createErrorResponse(validationResult.errorMessage(), request);   
+            }
         }
         
         // Call service layer to get films
@@ -151,25 +158,55 @@ public ResponseEntity<FilmResponse> getFilms(
      * - Cannot be numeric or special characters
      * 
      * @param startsWith The parameter value to validate
-     * @throws IllegalArgumentException if the parameter is invalid
+     * @return ValidationResult containing validation status and error message if invalid
      */
-    private void validateStartsWithParameter(String startsWith) {
-        if (startsWith == null || startsWith.trim().isEmpty()) {
-            throw new IllegalArgumentException("Parameter 'startsWith' cannot be empty");
+    private ValidationResult validateStartsWithParameter(String startsWith) {
+        if (Objects.isNull(startsWith) || startsWith.trim().isEmpty()) {
+            return new ValidationResult(false, "Parameter 'startsWith' cannot be empty");
         }
         
         String trimmed = startsWith.trim();
         
         // Check if it's a single character
         if (trimmed.length() != 1) {
-            throw new IllegalArgumentException("Parameter 'startsWith' must be a single letter (A-Z)");
+            return new ValidationResult(false, "Parameter 'startsWith' must be a single letter (A-Z)");
         }
         
         char character = trimmed.charAt(0);
         
         // Check if it's a letter (A-Z, a-z)
         if (!Character.isLetter(character)) {
-            throw new IllegalArgumentException("Parameter 'startsWith' must be a single letter (A-Z)");
+            return new ValidationResult(false, "Parameter 'startsWith' must be a single letter (A-Z)");
         }
+        
+        return new ValidationResult(true, null);
+    }
+    
+    /**
+     * Creates an error response matching the format from GlobalExceptionHandler
+     * 
+     * @param errorMessage The error message to include in the response
+     * @param request The HTTP request for building the error response
+     * @return ResponseEntity with ProblemDetail matching GlobalExceptionHandler format
+     */
+    private ResponseEntity<ProblemDetail> createErrorResponse(String errorMessage, HttpServletRequest request) {
+        ProblemDetail problemDetail = ProblemDetail.forStatusAndDetail(
+            HttpStatus.BAD_REQUEST, errorMessage
+        );
+        
+        problemDetail.setType(URI.create("https://example.com/problems/invalid-parameter"));
+        problemDetail.setTitle("Invalid Parameter");
+        problemDetail.setInstance(URI.create(request.getRequestURI()));
+        problemDetail.setProperty("timestamp", Instant.now());
+        
+        return ResponseEntity.badRequest().body(problemDetail);
     }
+    
+    /**
+     * Record to hold validation result with validation status and error message
+     * 
+     * @param valid true if validation passed, false otherwise
+     * @param errorMessage error message if validation failed, null if valid
+     */
+    private record ValidationResult(boolean valid, String errorMessage) { }
 } 
diff --git a/examples/spring-boot-demo/implementation/src/main/java/com/example/demo/controller/GlobalExceptionHandler.java b/examples/spring-boot-demo/implementation/src/main/java/com/example/demo/controller/GlobalExceptionHandler.java
@@ -40,31 +40,7 @@
 public class GlobalExceptionHandler {
     
     private static final Logger logger = LoggerFactory.getLogger(GlobalExceptionHandler.class);
-    
-    /**
-     * Task 10.2: Implement handleIllegalArgumentException method
-     * 
-     * Handles IllegalArgumentException for parameter validation errors.
-     * Returns HTTP 400 Bad Request with RFC 7807 Problem Details format.
-     */
-    @ExceptionHandler(IllegalArgumentException.class)
-    public ResponseEntity<ProblemDetail> handleIllegalArgumentException(
-            IllegalArgumentException ex, HttpServletRequest request) {
         
-        logger.warn("Invalid parameter request: {}", ex.getMessage());
-        
-        ProblemDetail problemDetail = ProblemDetail.forStatusAndDetail(
-            HttpStatus.BAD_REQUEST, ex.getMessage()
-        );
-        
-        problemDetail.setType(URI.create("https://example.com/problems/invalid-parameter"));
-        problemDetail.setTitle("Invalid Parameter");
-        problemDetail.setInstance(URI.create(request.getRequestURI()));
-        problemDetail.setProperty("timestamp", Instant.now());
-        
-        return ResponseEntity.badRequest().body(problemDetail);
-    }
-    
     /**
      * Handle RuntimeException for unexpected errors.
      * Returns HTTP 500 Internal Server Error with RFC 7807 Problem Details format.
diff --git a/examples/spring-boot-demo/implementation/src/main/java/com/example/demo/dto/FilmResponse.java b/examples/spring-boot-demo/implementation/src/main/java/com/example/demo/dto/FilmResponse.java
@@ -26,77 +26,8 @@
  *   }
  * }
  */
-public class FilmResponse {
-    
-    @JsonProperty("films")
-    private List<Map<String, Object>> films;
-    
-    @JsonProperty("count")
-    private int count;
-    
-    @JsonProperty("filter")
-    private Map<String, Object> filter;
-    
-    // Default constructor
-    public FilmResponse() {}
-    
-    // Constructor with all fields
-    public FilmResponse(List<Map<String, Object>> films, int count, Map<String, Object> filter) {
-        this.films = films;
-        this.count = count;
-        this.filter = filter;
-    }
-    
-    // Getters and setters
-    public List<Map<String, Object>> getFilms() {
-        return films;
-    }
-    
-    public void setFilms(List<Map<String, Object>> films) {
-        this.films = films;
-    }
-    
-    public int getCount() {
-        return count;
-    }
-    
-    public void setCount(int count) {
-        this.count = count;
-    }
-    
-    public Map<String, Object> getFilter() {
-        return filter;
-    }
-    
-    public void setFilter(Map<String, Object> filter) {
-        this.filter = filter;
-    }
-    
-    @Override
-    public boolean equals(Object obj) {
-        if (this == obj) return true;
-        if (obj == null || getClass() != obj.getClass()) return false;
-        
-        FilmResponse that = (FilmResponse) obj;
-        return count == that.count &&
-               films != null ? films.equals(that.films) : that.films == null &&
-               filter != null ? filter.equals(that.filter) : that.filter == null;
-    }
-    
-    @Override
-    public int hashCode() {
-        int result = films != null ? films.hashCode() : 0;
-        result = 31 * result + count;
-        result = 31 * result + (filter != null ? filter.hashCode() : 0);
-        return result;
-    }
-    
-    @Override
-    public String toString() {
-        return "FilmResponse{" +
-                "films=" + films +
-                ", count=" + count +
-                ", filter=" + filter +
-                '}';
-    }
-} 
+public record FilmResponse(
+    @JsonProperty("films") List<Map<String, Object>> films,
+    @JsonProperty("count") int count,
+    @JsonProperty("filter") Map<String, Object> filter
+) {} 
diff --git a/examples/spring-boot-demo/implementation/src/main/java/com/example/demo/repository/FilmRepository.java b/examples/spring-boot-demo/implementation/src/main/java/com/example/demo/repository/FilmRepository.java
@@ -2,7 +2,7 @@
 
 import com.example.demo.entity.Film;
 import org.springframework.data.jdbc.repository.query.Query;
-import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.ListCrudRepository;
 import org.springframework.data.repository.query.Param;
 import org.springframework.stereotype.Repository;
 
@@ -18,7 +18,7 @@
  * Task 8.4: Implement findByTitleStartingWith(String prefix) method ✅
  */
 @Repository
-public interface FilmRepository extends CrudRepository<Film, Integer> {
+public interface FilmRepository extends ListCrudRepository<Film, Integer> {
 
     /**
      * Task 8.4: Implement findByTitleStartingWith(String prefix) method
diff --git a/examples/spring-boot-demo/implementation/src/main/java/com/example/demo/service/FilmService.java b/examples/spring-boot-demo/implementation/src/main/java/com/example/demo/service/FilmService.java
@@ -6,8 +6,8 @@
 import org.springframework.stereotype.Service;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.HashMap;
-import java.util.stream.Collectors;
 
 /**
  * FilmService - Business Logic Layer for Film Query Operations
@@ -50,7 +50,7 @@ public List<Map<String, Object>> findFilmsByStartingLetter(String letter) {
         
         // Task 6.3: Add business validation for letter parameter (already done in controller)
         // Task 6.4: Implement film filtering logic (case insensitive LIKE query)
-        if (letter != null && !letter.trim().isEmpty()) {
+        if (Objects.nonNull(letter) && !letter.trim().isEmpty()) {
             // Get films starting with the specified letter (case insensitive)
             films = filmRepository.findByTitleStartingWith(letter.trim());
         } else {
@@ -62,7 +62,7 @@ public List<Map<String, Object>> findFilmsByStartingLetter(String letter) {
         // Transform Film entities to Map<String, Object> format expected by controller
         return films.stream()
                 .map(this::filmToMap)
-                .collect(Collectors.toList());
+                .toList();
     }
     
     /**
