Add comment subject ID and omit zero-value reaction counters

src/CrowdParlay.Social.Api/v1/Controllers/CommentsController.cs

@@ -60,7 +60,7 @@ public async Task<Page<CommentResponse>> GetReplies(
     [ProducesResponseType<ProblemDetails>(Status403Forbidden)]
     [ProducesResponseType<ProblemDetails>(Status404NotFound)]
     [ProducesResponseType<ProblemDetails>(Status500InternalServerError)]
-    public async Task<ActionResult<CommentResponse>> Reply([FromRoute] string commentId, [FromBody] ReplyRequest request)
+    public async Task<ActionResult<CommentResponse>> Reply([FromRoute] string commentId, [FromBody] CommentRequest request)
     {
         var response = await commentsService.ReplyToCommentAsync(commentId, User.GetRequiredUserId(), request.Content);
         return CreatedAtAction(nameof(GetById), new { commentId = response.Id }, response);

src/CrowdParlay.Social.Api/v1/Controllers/DiscussionsController.cs

@@ -49,7 +49,7 @@ public async Task<Page<DiscussionResponse>> Search(
         await discussionsService.SearchAsync(authorId, User.GetUserId(), offset, count);
 
     /// <summary>
-    /// Retrieves top-level comments for a specified discussion with pagination.
+    /// Retrieves comments for a specified discussion with configurable tree traversal and pagination.
     /// </summary>
     /// <param name="discussionId">The unique identifier of the discussion.</param>
     /// <param name="flatten">When true, returns all nested replies in a flat structure; otherwise returns direct children only.</param>
@@ -70,6 +70,7 @@ public async Task<Page<CommentResponse>> GetComments(
     /// <summary>
     /// Creates a new top-level comment in a discussion. Requires authenticated user and triggers real-time notifications.
     /// </summary>
+    /// <param name="discussionId">The unique identifier of the discussion being commented.</param>
     /// <param name="request">The comment content and target discussion identifier.</param>
     /// <returns>The newly created top-level comment details.</returns>
     [HttpPost("{discussionId}/comments"), Authorize]
@@ -78,12 +79,13 @@ public async Task<Page<CommentResponse>> GetComments(
     [ProducesResponseType<ValidationProblemDetails>(Status400BadRequest)]
     [ProducesResponseType<ProblemDetails>(Status403Forbidden)]
     [ProducesResponseType<ProblemDetails>(Status500InternalServerError)]
-    public async Task<ActionResult<CommentResponse>> Reply([FromBody] CommentRequest request)
+    public async Task<ActionResult<CommentResponse>> Comment([FromRoute] string discussionId, [FromBody] CommentRequest request)
     {
-        var response = await commentsService.ReplyToDiscussionAsync(request.DiscussionId, User.GetRequiredUserId(), request.Content);
+        var response = await commentsService.ReplyToDiscussionAsync(discussionId, User.GetRequiredUserId(), request.Content);
 
+        // TODO: handle exceptions and move to a better place
         _ = commentHub.Clients
-            .Group(CommentsHub.GroupNames.NewCommentInDiscussion(request.DiscussionId))
+            .Group(CommentsHub.GroupNames.NewCommentInDiscussion(discussionId))
             .SendCoreAsync(CommentsHub.Events.NewComment.ToString(), [response]);
 
         return CreatedAtAction(nameof(CommentsController.GetById), "Comments", new { commentId = response.Id }, response);

src/CrowdParlay.Social.Application/DTOs/CommentRequest.cs

@@ -1,3 +1,3 @@
 namespace CrowdParlay.Social.Application.DTOs;
 
-public record CommentRequest(string DiscussionId, string Content);
+public record CommentRequest(string Content);

src/CrowdParlay.Social.Application/DTOs/CommentResponse.cs

@@ -3,6 +3,7 @@ namespace CrowdParlay.Social.Application.DTOs;
 public class CommentResponse
 {
     public required string Id { get; set; }
+    public required string SubjectId { get; set; }
     public required string Content { get; set; }
     public required AuthorResponse? Author { get; set; }
     public required DateTimeOffset CreatedAt { get; set; }

src/CrowdParlay.Social.Application/Services/CommentsService.cs

@@ -106,6 +106,7 @@ private async Task<IEnumerable<CommentResponse>> EnrichAsync(IReadOnlyList<Comme
         return comments.Select(comment => new CommentResponse
         {
             Id = comment.Id,
+            SubjectId = comment.SubjectId,
             Content = comment.Content,
             Author = authorsById[comment.AuthorId].Adapt<AuthorResponse>(),
             CreatedAt = comment.CreatedAt,

src/CrowdParlay.Social.Application/Services/SubjectsService.cs

@@ -19,9 +19,10 @@ public async Task SetReactionsAsync(string subjectId, Guid authorId, ISet<string
             throw new ForbiddenException("Such reaction set is not allowed.");
 
         await subjectsRepository.SetReactionsAsync(subjectId, authorId, newReactions);
-
-        var reactionsToAdd = newReactions.Except(oldReactions).ToArray();
-        var reactionsToRemove = oldReactions.Except(newReactions).ToArray();
-        await subjectsRepository.UpdateReactionCountersAsync(subjectId, reactionsToAdd, reactionsToRemove);
+
+        var addedReactionsDiff = newReactions.Except(oldReactions).Select(reaction => new KeyValuePair<string, int>(reaction, 1));
+        var removedReactionsDiff = oldReactions.Except(newReactions).Select(reaction => new KeyValuePair<string, int>(reaction, -1));
+        var reactionsDiff = addedReactionsDiff.Concat(removedReactionsDiff).ToDictionary();
+        await subjectsRepository.UpdateReactionCountersAsync(subjectId, reactionsDiff);
     }
 }

src/CrowdParlay.Social.Domain/Abstractions/ISubjectsRepository.cs

@@ -4,7 +4,7 @@ public interface ISubjectsRepository
 {
     public Task<ISet<string>> GetReactionsAsync(string subjectId, Guid authorId);
     public Task SetReactionsAsync(string subjectId, Guid authorId, ISet<string> reactions);
-    public Task UpdateReactionCountersAsync(string subjectId, IEnumerable<string> reactionsToAdd, IEnumerable<string> reactionsToRemove);
+    public Task UpdateReactionCountersAsync(string subjectId, IDictionary<string, int> reactionsDiff);
     public Task IncludeCommentInMetadataAsync(string discussionId, Guid authorId);
     public Task ExcludeCommentFromMetadataAsync(string discussionId);
 

src/CrowdParlay.Social.Domain/Entities/Comment.cs

@@ -2,7 +2,6 @@
 
 namespace CrowdParlay.Social.Domain.Entities;
 
-
 [DebuggerDisplay("{Id} by {AuthorId} in reply to {SubjectId}")]
 public class Comment
 {
@@ -13,6 +12,12 @@ public class Comment
     public required DateTimeOffset CreatedAt { get; set; }
     public required int CommentCount { get; set; }
     public required IList<Guid> LastCommentsAuthorIds { get; set; }
-    public required IDictionary<string, int> ReactionCounters { get; set; }
     public required IList<string> ViewerReactions { get; set; }
+
+    private IDictionary<string, int> _reactionCounters = null!;
+    public required IDictionary<string, int> ReactionCounters
+    {
+        get => _reactionCounters;
+        set => _reactionCounters = value.Where(kv => kv.Value > 0).ToDictionary();
+    }
 }

src/CrowdParlay.Social.Domain/Entities/Discussion.cs

@@ -2,7 +2,6 @@
 
 namespace CrowdParlay.Social.Domain.Entities;
 
-
 [DebuggerDisplay("{Id} by {AuthorId}")]
 public class Discussion
 {
@@ -13,6 +12,12 @@ public class Discussion
     public required DateTimeOffset CreatedAt { get; set; }
     public required int CommentCount { get; set; }
     public required IList<Guid> LastCommentsAuthorIds { get; set; }
-    public required IDictionary<string, int> ReactionCounters { get; set; }
     public required IList<string> ViewerReactions { get; set; }
+
+    private IDictionary<string, int> _reactionCounters = null!;
+    public required IDictionary<string, int> ReactionCounters
+    {
+        get => _reactionCounters;
+        set => _reactionCounters = value.Where(kv => kv.Value > 0).ToDictionary();
+    }
 }

src/CrowdParlay.Social.Infrastructure.Persistence/Services/CommentsRepository.cs

@@ -160,8 +160,8 @@ public async Task<ISet<string>> GetReactionsAsync(string commentId, Guid authorI
     public async Task SetReactionsAsync(string commentId, Guid authorId, ISet<string> reactions) =>
         await _subjectsRepository.SetReactionsAsync(commentId, authorId, reactions);
 
-    public async Task UpdateReactionCountersAsync(string commentId, IEnumerable<string> reactionsToAdd, IEnumerable<string> reactionsToRemove) =>
-        await _subjectsRepository.UpdateReactionCountersAsync(commentId, reactionsToAdd, reactionsToRemove);
+    public async Task UpdateReactionCountersAsync(string commentId, IDictionary<string, int> reactionsDiff) =>
+        await _subjectsRepository.UpdateReactionCountersAsync(commentId, reactionsDiff);
 
     private static Expression<Func<CommentDocument, Comment>> CreateCommentProjectionExpression(Guid? viewerId) => comment => new Comment
     {

src/CrowdParlay.Social.Infrastructure.Persistence/Services/DiscussionsRepository.cs

@@ -105,8 +105,8 @@ public async Task<ISet<string>> GetReactionsAsync(string discussionId, Guid auth
     public async Task SetReactionsAsync(string discussionId, Guid authorId, ISet<string> reactions) =>
         await _subjectsRepository.SetReactionsAsync(discussionId, authorId, reactions);
 
-    public async Task UpdateReactionCountersAsync(string subjectId, IEnumerable<string> reactionsToAdd, IEnumerable<string> reactionsToRemove) =>
-        await _subjectsRepository.UpdateReactionCountersAsync(subjectId, reactionsToAdd, reactionsToRemove);
+    public async Task UpdateReactionCountersAsync(string subjectId, IDictionary<string, int> reactionsDiff) =>
+        await _subjectsRepository.UpdateReactionCountersAsync(subjectId, reactionsDiff);
 
     public async Task IncludeCommentInMetadataAsync(string discussionId, Guid authorId) =>
         await _subjectsRepository.IncludeCommentInMetadataAsync(discussionId, authorId);

src/CrowdParlay.Social.Infrastructure.Persistence/Services/GenericSubjectsRepository.cs

@@ -16,8 +16,8 @@ public async Task<ISet<string>> GetReactionsAsync(string subjectId, Guid authorI
         var pipeline = _subjects
             .Find(session, subject => subject.Id == ObjectId.Parse(subjectId))
             .Project(subject => subject.ReactionsByAuthorId.ContainsKey(authorId.ToString())
-                    ? subject.ReactionsByAuthorId[authorId.ToString()]
-                    : new string[] { });
+                ? subject.ReactionsByAuthorId[authorId.ToString()]
+                : new string[] { });
 
         var reactions = await pipeline.FirstOrDefaultAsync() ?? throw new NotFoundException();
         return reactions.ToHashSet();
@@ -38,16 +38,13 @@ public async Task SetReactionsAsync(string subjectId, Guid authorId, ISet<string
             throw new NotFoundException();
     }
 
-    public async Task UpdateReactionCountersAsync(string subjectId, IEnumerable<string> reactionsToAdd, IEnumerable<string> reactionsToRemove)
+    public async Task UpdateReactionCountersAsync(string subjectId, IDictionary<string, int> reactionsDiff)
     {
-        var increments = reactionsToAdd.Select(reaction =>
-            Builders<TDocument>.Update.Inc(subject => subject.ReactionCounters[reaction], 1));
-
-        var decrements = reactionsToRemove.Select(reaction =>
-            Builders<TDocument>.Update.Inc(subject => subject.ReactionCounters[reaction], -1));
+        var updates = reactionsDiff.Select(kv =>
+            Builders<TDocument>.Update.Inc(subject => subject.ReactionCounters[kv.Key], kv.Value));
 
         var filter = Builders<TDocument>.Filter.Eq(subject => subject.Id, ObjectId.Parse(subjectId));
-        var update = Builders<TDocument>.Update.Combine(increments.Union(decrements));
+        var update = Builders<TDocument>.Update.Combine(updates);
         var result = await _subjects.UpdateOneAsync(session, filter, update);
 
         if (result.MatchedCount == 0)
@@ -76,7 +73,7 @@ await _subjects
 
         await _subjects.UpdateOneAsync(session, filter, update);
     }
-    
+
     public async Task ExcludeCommentFromMetadataAsync(string subjectId)
     {
         var filter = Builders<TDocument>.Filter.Eq(subject => subject.Id, ObjectId.Parse(subjectId));

tests/CrowdParlay.Social.IntegrationTests/Tests/ReactionsTests.cs

@@ -2,7 +2,7 @@
 
 namespace CrowdParlay.Social.IntegrationTests.Tests;
 
 public class ReactionsTests(WebApplicationContext context) : IAssemblyFixture<WebApplicationContext>
 {
     private readonly IServiceProvider _services = context.Services;
 
@@ -66,9 +66,7 @@
         discussion.ViewerReactions.Should().BeEquivalentTo(woozyFace, redHeart);
         discussion.ReactionCounters.Should().BeEquivalentTo(new Dictionary<string, int>
         {
-            { eggplant, 0 },
             { woozyFace, 1 },
-            { nailPolish, 0 },
             { redHeart, 1 }
         });
     }

tests/CrowdParlay.Social.IntegrationTests/Tests/SignalRTests.cs

@@ -6,7 +6,7 @@
 
 namespace CrowdParlay.Social.IntegrationTests.Tests;
 
 public class SignalRTests(WebApplicationContext context) : IAssemblyFixture<WebApplicationContext>
 {
     private readonly IServiceProvider _services = context.Services;
     private readonly HttpClient _client = context.Server.CreateClient();
@@ -24,6 +24,7 @@
         var expectedComment = new CommentResponse
         {
             Id = ObjectId.GenerateNewId().ToString(),
+            SubjectId = discussionId,
             Content = "Sample comment.",
             Author = new AuthorResponse
             {