Fix(Java): update logic around voyage api key

mflix/server/java-spring/.env.example

@@ -2,9 +2,11 @@
 # Replace with your MongoDB Atlas connection string or local MongoDB URI
 MONGODB_URI=mongodb+srv://<username>:<password>@<cluster>.mongodb.net/sample_mflix?retryWrites=true&w=majority
 
-# Voyage AI Configuration
+# Optional: Voyage AI Configuration
 # API key for Voyage AI embedding model (required for Vector Search)
-VOYAGE_API_KEY=your_voyage_api_key
+# Get your API key from https://www.voyageai.com/
+# Uncomment the following line to enable vector search
+# VOYAGE_API_KEY=your-api-key
 
 # Server Configuration
 # Port on which the Spring Boot application will run

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

@@ -819,9 +819,10 @@ public List<VectorSearchResult> vectorSearchMovies(String query, Integer limit)
         }
 
         // Check if Voyage API key is configured
-        if (voyageApiKey == null || voyageApiKey.trim().isEmpty()) {
+        if (voyageApiKey == null || voyageApiKey.trim().isEmpty() ||
+            voyageApiKey.equals("your_voyage_api_key")) {
             throw new ValidationException(
-                "Vector search unavailable: VOYAGE_API_KEY not configured. Please add your API key to the application.properties file"
+                "Vector search unavailable: VOYAGE_API_KEY not configured. Please add your Voyage AI API key to the .env file"
             );
         }
 
@@ -978,6 +979,10 @@ private List<Double> generateVoyageEmbedding(String text, String apiKey) throws
 
         // Check for successful response
         if (response.statusCode() != 200) {
+            // Handle authentication errors specifically
+            if (response.statusCode() == 401) {
+                throw new IOException("Invalid Voyage AI API key. Please check your VOYAGE_API_KEY in the .env file");
+            }
             throw new IOException("Voyage AI API returned status code " + response.statusCode() + ": " + response.body());
         }
 

mflix/server/java-spring/src/test/java/com/mongodb/samplemflix/service/MovieServiceTest.java

@@ -745,6 +745,16 @@ void testVectorSearchMovies_MissingApiKey() {
         assertThrows(ValidationException.class, () -> movieService.vectorSearchMovies("test query", 10));
     }
 
+    @Test
+    @DisplayName("Should throw ValidationException when API key is placeholder value in vector search")
+    void testVectorSearchMovies_PlaceholderApiKey() {
+        // Arrange
+        ReflectionTestUtils.setField(movieService, "voyageApiKey", "your_voyage_api_key");
+
+        // Act & Assert
+        assertThrows(ValidationException.class, () -> movieService.vectorSearchMovies("test query", 10));
+    }
+
     @Test
     @DisplayName("Should enforce limit constraints in vector search")
     void testVectorSearchMovies_LimitConstraints() {