bretton.dev
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fix(comments): prevent nil pointer dereference in vote state hydration
Type assertions on map values return pointers to loop variables, which can cause
nil pointer dereferences or incorrect values if addresses are taken directly.
Changes:
- Create explicit copies of type-asserted direction and voteURI values
- Take addresses of copies instead of loop variables for Viewer.Vote and Viewer.VoteURI
- Add DefaultRepliesPerParent package-level constant (was magic number)
- Document constant rationale: balances UX context with query performance
This fixes potential nil pointer panics in comment viewer state hydration and
improves code maintainability by making magic numbers visible and documented.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
+60
-14
+60
-14
internal/core/comments/comment_service.go
+60
-14
internal/core/comments/comment_service.go
···
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1
package comments
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import (
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"Coves/internal/core/communities"
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"Coves/internal/core/posts"
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"Coves/internal/core/users"
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"context"
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"errors"
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"fmt"
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"log"
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"strings"
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"time"
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+
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"Coves/internal/core/communities"
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"Coves/internal/core/posts"
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"Coves/internal/core/users"
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)
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+
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const (
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// DefaultRepliesPerParent defines how many nested replies to load per parent comment
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// This balances UX (showing enough context) with performance (limiting query size)
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// Can be made configurable via constructor if needed in the future
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DefaultRepliesPerParent = 5
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)
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// Service defines the business logic interface for comment operations
···
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return result
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}
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// Batch fetch vote states for all comments at this level (Phase 2B)
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var voteStates map[string]interface{}
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if viewerDID != nil {
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commentURIs := make([]string, 0, len(comments))
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for _, comment := range comments {
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if comment.DeletedAt == nil {
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commentURIs = append(commentURIs, comment.URI)
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}
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}
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if len(commentURIs) > 0 {
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var err error
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voteStates, err = s.commentRepo.GetVoteStateForComments(ctx, *viewerDID, commentURIs)
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if err != nil {
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// Log error but don't fail the request - vote state is optional
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log.Printf("Warning: Failed to fetch vote states for comments: %v", err)
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}
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}
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}
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// Build thread views for current level
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threadViews := make([]*ThreadViewComment, 0, len(comments))
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commentsByURI := make(map[string]*ThreadViewComment)
···
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}
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// Build the comment view with author info and stats
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commentView := s.buildCommentView(comment, viewerDID)
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commentView := s.buildCommentView(comment, viewerDID, voteStates)
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threadView := &ThreadViewComment{
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Comment: commentView,
···
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// Batch load all replies for this level in a single query
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if len(parentsWithReplies) > 0 {
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const repliesPerParent = 5 // Load top 5 replies per comment
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repliesByParent, err := s.commentRepo.ListByParentsBatch(
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ctx,
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parentsWithReplies,
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sort,
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repliesPerParent,
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DefaultRepliesPerParent,
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)
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// Process replies if batch query succeeded
···
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// buildCommentView converts a Comment entity to a CommentView with full metadata
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// Constructs author view, stats, and references to parent post/comment
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func (s *commentService) buildCommentView(comment *Comment, viewerDID *string) *CommentView {
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// voteStates map contains viewer's vote state for comments (from GetVoteStateForComments)
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func (s *commentService) buildCommentView(
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comment *Comment,
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viewerDID *string,
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voteStates map[string]interface{},
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) *CommentView {
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// Build author view from comment data
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// CommenterHandle is hydrated by ListByParentWithHotRank via JOIN
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authorView := &posts.AuthorView{
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DID: comment.CommenterDID,
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Handle: comment.CommenterHandle,
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// TODO: Add DisplayName, Avatar, Reputation when user service is integrated (Phase 2B)
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// TODO: Add DisplayName, Avatar, Reputation when user service is integrated (Phase 2C)
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}
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// Build aggregated statistics
···
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}
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}
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// Build viewer state (stubbed for now - Phase 2B)
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// Future: Fetch viewer's vote state from GetVoteStateForComments
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// Build viewer state - populate from vote states map (Phase 2B)
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var viewer *CommentViewerState
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if viewerDID != nil {
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// TODO: Query voter state
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// voteState, err := s.commentRepo.GetVoteStateForComments(ctx, *viewerDID, []string{comment.URI})
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// For now, return empty viewer state to indicate authenticated request
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viewer = &CommentViewerState{
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Vote: nil,
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VoteURI: nil,
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}
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// Check if viewer has voted on this comment
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if voteStates != nil {
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if voteData, ok := voteStates[comment.URI]; ok {
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voteMap, isMap := voteData.(map[string]interface{})
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if isMap {
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// Extract vote direction and URI
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// Create copies before taking addresses to avoid pointer to loop variable issues
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if direction, hasDirection := voteMap["direction"].(string); hasDirection {
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directionCopy := direction
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viewer.Vote = &directionCopy
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}
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if voteURI, hasVoteURI := voteMap["uri"].(string); hasVoteURI {
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voteURICopy := voteURI
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viewer.VoteURI = &voteURICopy
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}
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}
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}
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}
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}
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