Add GET /api/movies/genres endpoint to Java Spring and Python FastAPI backends

- Java: Added getDistinctGenres() to MovieService interface and MovieServiceImpl
- Java: Added /genres endpoint to MovieControllerImpl using mongoTemplate.findDistinct()
- Python: Added /genres endpoint to movies.py router using collection.distinct()
- Both implementations filter null/empty values and sort alphabetically
- Returns success response with count of distinct genres

Author: cbullinger

mflix/server/java-spring/src/main/java/com/mongodb/samplemflix/controller/MovieControllerImpl.java

@@ -109,7 +109,26 @@ public ResponseEntity<SuccessResponse<List<Movie>>> getAllMovies(
 
         return ResponseEntity.ok(response);
     }
-    
+
+    @Operation(
+        summary = "Get all distinct genres",
+        description = "Retrieve a list of all unique genre values from the movies collection. " +
+                     "Demonstrates the distinct() operation. Returns genres sorted alphabetically."
+    )
+    @GetMapping("/genres")
+    public ResponseEntity<SuccessResponse<List<String>>> getDistinctGenres() {
+        List<String> genres = movieService.getDistinctGenres();
+
+        SuccessResponse<List<String>> response = SuccessResponse.<List<String>>builder()
+                .success(true)
+                .message("Found " + genres.size() + " distinct genres")
+                .data(genres)
+                .timestamp(Instant.now().toString())
+                .build();
+
+        return ResponseEntity.ok(response);
+    }
+
     @Operation(
         summary = "Get a single movie by ID",
         description = "Retrieve a single movie by its MongoDB ObjectId."

mflix/server/java-spring/src/main/java/com/mongodb/samplemflix/service/MovieService.java

@@ -21,6 +21,14 @@ public interface MovieService {
 
     List<Movie> getAllMovies(MovieSearchQuery query);
 
+    /**
+     * Gets all distinct genre values from the movies collection.
+     * Demonstrates the distinct() operation.
+     *
+     * @return List of unique genre strings, sorted alphabetically
+     */
+    List<String> getDistinctGenres();
+
     Movie getMovieById(String id);
 
     Movie createMovie(CreateMovieRequest request);

mflix/server/java-spring/src/main/java/com/mongodb/samplemflix/service/MovieServiceImpl.java

@@ -85,7 +85,25 @@ public List<Movie> getAllMovies(MovieSearchQuery query) {
 
         return mongoTemplate.find(mongoQuery, Movie.class);
     }
-    
+
+    @Override
+    public List<String> getDistinctGenres() {
+        // Use MongoTemplate's findDistinct to get all unique values from the genres array field
+        // MongoDB automatically flattens array fields when using distinct()
+        List<String> genres = mongoTemplate.findDistinct(
+                new Query(),
+                Movie.Fields.GENRES,
+                Movie.class,
+                String.class
+        );
+
+        // Filter out null/empty values and sort alphabetically
+        return genres.stream()
+                .filter(genre -> genre != null && !genre.isEmpty())
+                .sorted(String::compareTo)
+                .collect(Collectors.toList());
+    }
+
     @Override
     public Movie getMovieById(String id) {
         if (!ObjectId.isValid(id)) {

mflix/server/python-fastapi/src/routers/movies.py

@@ -32,6 +32,10 @@
     Search movies using MongoDB Vector Search to enable semantic search capabilities over
     the plot field.
 
+- GET /api/movies/genres :
+    Retrieve all distinct genre values from the movies collection.
+    Demonstrates the distinct() operation.
+
 - GET /api/movies/{id} :
     Retrieve a single movie by its ID.
 
@@ -427,6 +431,41 @@ async def vector_search_movies(
             detail=f"Error performing vector search: {str(e)}"
         )
 
+"""
+    GET /api/movies/genres
+
+    Retrieve all distinct genre values from the movies collection.
+    Demonstrates the distinct() operation.
+
+    Returns:
+        SuccessResponse[List[str]]: A response object containing the list of unique genres, sorted alphabetically.
+"""
+
+@router.get("/genres",
+            response_model=SuccessResponse[List[str]],
+            status_code=200,
+            summary="Retrieve all distinct genres from the movies collection.")
+async def get_distinct_genres():
+    movies_collection = get_collection("movies")
+
+    try:
+        # Use distinct() to get all unique values from the genres array field
+        # MongoDB automatically flattens array fields when using distinct()
+        genres = await movies_collection.distinct("genres")
+    except Exception as e:
+        raise HTTPException(
+            status_code=500,
+            detail=f"Database error occurred: {str(e)}"
+        )
+
+    # Filter out null/empty values and sort alphabetically
+    valid_genres = sorted([
+        genre for genre in genres
+        if isinstance(genre, str) and len(genre) > 0
+    ])
+
+    return create_success_response(valid_genres, f"Found {len(valid_genres)} distinct genres")
+
 """
     GET /api/movies/{id}
     Retrieve a single movie by its ID.