Replace java.util.Date with Instant and LocalDate for MongoDB datetime fields

Author: ozgliderpilot

mflix/server/java-spring/src/main/java/com/mongodb/samplemflix/config/MongoConfig.java

@@ -9,6 +9,7 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.data.mongodb.config.AbstractMongoClientConfiguration;
+import org.springframework.data.mongodb.core.convert.MongoCustomConversions;
 import org.springframework.data.mongodb.repository.config.EnableMongoRepositories;
 import org.springframework.lang.NonNull;
 
@@ -119,4 +120,9 @@ public MongoDatabase mongoDatabase() {
 
         return client.getDatabase(databaseName);
     }
+
+    @Bean
+    public MongoCustomConversions customConversions() {
+        return MongoCustomConversions.create(MongoCustomConversions.MongoConverterConfigurationAdapter::useNativeDriverJavaTimeCodecs);
+    }
 }

mflix/server/java-spring/src/main/java/com/mongodb/samplemflix/model/Movie.java

@@ -1,7 +1,8 @@
 package com.mongodb.samplemflix.model;
 
 import com.fasterxml.jackson.annotation.JsonProperty;
-import java.util.Date;
+import java.time.Instant;
+import java.time.LocalDate;
 import java.util.List;
 import lombok.AccessLevel;
 import lombok.AllArgsConstructor;
@@ -111,9 +112,14 @@ private Fields() {
     private String fullplot;
 
     /**
-     * Release date.
+     * Release date as a calendar date (no time-of-day or time zone).
+     *
+     * <p>A movie release date is a "date only" concept (e.g. "1999-03-31"), not a specific
+     * moment in time. We use {@link LocalDate} because it represents exactly that: a date
+     * without time-of-day or time zone information. Spring Data MongoDB maps this via the
+     * Jsr310 {@code LocalDateCodec}.
      */
-    private Date released;
+    private LocalDate released;
 
     /**
      * Runtime in minutes.
@@ -270,9 +276,12 @@ public static class Tomatoes {
         private String production;
 
         /**
-         * Last updated date.
+         * Timestamp of the last update to Tomatoes ratings.
+         *
+         * <p>Stored as BSON DateTime in MongoDB. Uses {@link Instant} for an immutable,
+         * UTC-only representation of this point-in-time event.
          */
-        private Date lastUpdated;
+        private Instant lastUpdated;
 
         /**
          * Nested class for viewer ratings.

mflix/server/java-spring/src/main/java/com/mongodb/samplemflix/model/dto/MovieWithCommentsResult.java

@@ -1,7 +1,7 @@
 package com.mongodb.samplemflix.model.dto;
 
 import com.fasterxml.jackson.annotation.JsonInclude;
-import java.util.Date;
+import java.time.Instant;
 import java.util.List;
 import lombok.Builder;
 
@@ -61,9 +61,12 @@ public record MovieWithCommentsResult (
     Integer totalComments,
 
     /**
-     * Date of the most recent comment.
+     * Timestamp of the most recent comment as a UTC instant.
+     *
+     * <p>Uses {@link Instant} for an immutable, unambiguous UTC representation.
+     * BSON DateTime values are converted via {@code Date.toInstant()}.
      */
-    Date mostRecentCommentDate) {
+    Instant mostRecentCommentDate) {
 
     /**
      * Nested record for comment information.
@@ -91,8 +94,11 @@ public record CommentInfo (
         String text,
 
         /**
-         * Comment date.
+         * Comment timestamp as a UTC instant.
+         *
+         * <p>Stored as BSON DateTime in MongoDB. Uses {@link Instant} for immutability
+         * and unambiguous UTC semantics.
          */
-        Date date) {}
+        Instant date) {}
 }
 

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

@@ -574,7 +574,7 @@ private MovieWithCommentsResult mapToMovieWithCommentsResult(Document doc) {
                             .name(commentDoc.getString("name"))
                             .email(commentDoc.getString("email"))
                             .text(commentDoc.getString("text"))
-                            .date(commentDoc.getDate("date"))
+                            .date(commentDoc.get("date") != null ? commentDoc.getDate("date").toInstant() : null)
                             .build())
                     .collect(Collectors.toList());
         }
@@ -598,7 +598,7 @@ private MovieWithCommentsResult mapToMovieWithCommentsResult(Document doc) {
                 .imdbRating(imdbRating)
                 .recentComments(recentComments)
                 .totalComments(doc.getInteger("totalComments"))
-                .mostRecentCommentDate(doc.getDate("mostRecentCommentDate"))
+                .mostRecentCommentDate(doc.getDate("mostRecentCommentDate") != null ? doc.getDate("mostRecentCommentDate").toInstant() : null)
                 .build();
     }
 

mflix/server/java-spring/src/test/java/com/mongodb/samplemflix/controller/MovieControllerTest.java

@@ -22,8 +22,8 @@
 import com.mongodb.samplemflix.model.dto.UpdateMovieRequest;
 import com.mongodb.samplemflix.model.dto.VectorSearchResult;
 import com.mongodb.samplemflix.service.MovieService;
+import java.time.Instant;
 import java.util.Arrays;
-import java.util.Date;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -343,7 +343,7 @@ void testGetMoviesWithMostComments_Success() throws Exception {
                 .name("John Doe")
                 .email("john@example.com")
                 .text("Great movie!")
-                .date(new Date())
+                .date(Instant.now())
                 .build();
 
         MovieWithCommentsResult result = MovieWithCommentsResult.builder()
@@ -356,7 +356,7 @@ void testGetMoviesWithMostComments_Success() throws Exception {
                 .imdbRating(8.5)
                 .recentComments(Arrays.asList(comment))
                 .totalComments(5)
-                .mostRecentCommentDate(new Date())
+                .mostRecentCommentDate(Instant.now())
                 .build();
 
         when(movieService.getMoviesWithMostRecentComments(anyInt(), isNull())).thenReturn(Arrays.asList(result));