Load more comments for a post

Signed-off-by: Vartan Benohanian <vartanbeno@gmail.com>

comment.go

@@ -71,7 +71,7 @@ func (s *CommentService) LoadMoreReplies(ctx context.Context, comment *Comment)
 		return nil, errors.New("comment: cannot be nil")
 	}
 
-	if !comment.hasMore() {
+	if !comment.HasMore() {
 		return nil, nil
 	}
 
@@ -108,23 +108,17 @@ func (s *CommentService) LoadMoreReplies(ctx context.Context, comment *Comment)
 	}
 
 	comments := root.JSON.Data.Things.Comments
+	mores := root.JSON.Data.Things.More
+
 	for _, c := range comments {
-		addCommentToReplies(comment, c)
+		comment.addCommentToReplies(c)
 	}
 
+	if len(mores) > 0 {
+		comment.Replies.More = mores[0]
+	} else {
 		comment.Replies.More = nil
+	}
+
 	return resp, nil
 }
-
-// addCommentToReplies traverses the comment tree to find the one
-// that the 2nd comment is replying to. It then adds it to its replies.
-func addCommentToReplies(parent *Comment, comment *Comment) {
-	if parent.FullID == comment.ParentID {
-		parent.Replies.Comments = append(parent.Replies.Comments, comment)
-		return
-	}
-
-	for _, reply := range parent.Replies.Comments {
-		addCommentToReplies(reply, comment)
-	}
-}

post.go

@@ -439,26 +439,23 @@ func (s *PostService) LoadMoreComments(ctx context.Context, pc *PostAndComments)
 		return nil, errors.New("pc: cannot be nil")
 	}
 
-	if !pc.hasMore() {
+	if !pc.HasMore() {
 		return nil, nil
 	}
 
 	postID := pc.Post.FullID
-	commentIDs := pc.moreComments.Children
+	commentIDs := pc.MoreComments.Children
 
-	type query struct {
-		PostID  string   `url:"link_id"`
-		IDs     []string `url:"children,comma"`
-		APIType string   `url:"api_type"`
-	}
+	form := url.Values{}
+	form.Set("api_type", "json")
+	form.Set("link_id", postID)
+	form.Set("children", strings.Join(commentIDs, ","))
 
 	path := "api/morechildren"
-	path, err := addOptions(path, query{postID, commentIDs, "json"})
-	if err != nil {
-		return nil, err
-	}
 
-	req, err := s.client.NewRequest(http.MethodGet, path, nil)
+	// This was originally a GET, but with POST you can send a bigger payload
+	// since it's in the body and not the URI.
+	req, err := s.client.NewRequestWithForm(http.MethodPost, path, form)
 	if err != nil {
 		return nil, err
 	}
@@ -477,24 +474,26 @@ func (s *PostService) LoadMoreComments(ctx context.Context, pc *PostAndComments)
 
 	comments := root.JSON.Data.Things.Comments
 	for _, c := range comments {
-		addCommentToTree(pc, c)
+		pc.addCommentToTree(c)
+	}
+
+	noMore := true
+
+	mores := root.JSON.Data.Things.More
+	for _, m := range mores {
+		if strings.HasPrefix(m.ParentID, kindPost+"_") {
+			noMore = false
+		}
+		pc.addMoreToTree(m)
+	}
+
+	if noMore {
+		pc.MoreComments = nil
 	}
 
-	pc.moreComments = nil
 	return resp, nil
 }
 
-func addCommentToTree(pc *PostAndComments, comment *Comment) {
-	if pc.Post.FullID == comment.ParentID {
-		pc.Comments = append(pc.Comments, comment)
-		return
-	}
-
-	for _, reply := range pc.Comments {
-		addCommentToReplies(reply, comment)
-	}
-}
-
 func (s *PostService) random(ctx context.Context, subreddits ...string) (*PostAndComments, *Response, error) {
 	path := "random"
 	if len(subreddits) > 0 {

things.go

@@ -176,16 +176,41 @@ type Comment struct {
 	Replies Replies `json:"replies"`
 }
 
-func (c *Comment) hasMore() bool {
+// HasMore determines whether the comment has more replies to load in its reply tree.
+func (c *Comment) HasMore() bool {
 	return c.Replies.More != nil && len(c.Replies.More.Children) > 0
 }
 
+// addCommentToReplies traverses the comment tree to find the one
+// that the 2nd comment is replying to. It then adds it to its replies.
+func (c *Comment) addCommentToReplies(comment *Comment) {
+	if c.FullID == comment.ParentID {
+		c.Replies.Comments = append(c.Replies.Comments, comment)
+		return
+	}
+
+	for _, reply := range c.Replies.Comments {
+		reply.addCommentToReplies(comment)
+	}
+}
+
+func (c *Comment) addMoreToReplies(more *More) {
+	if c.FullID == more.ParentID {
+		c.Replies.More = more
+		return
+	}
+
+	for _, reply := range c.Replies.Comments {
+		reply.addMoreToReplies(more)
+	}
+}
+
 // Replies holds replies to a comment.
 // It contains both comments and "more" comments, which are entrypoints to other
 // comments that were left out.
 type Replies struct {
 	Comments []*Comment `json:"comments,omitempty"`
-	More     *More      `json:"more,omitempty"`
+	More     *More      `json:"-"`
 }
 
 // UnmarshalJSON implements the json.Unmarshaler interface.
@@ -208,6 +233,14 @@ func (r *Replies) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
+// MarshalJSON implements the json.Marshaler interface.
+func (r *Replies) MarshalJSON() ([]byte, error) {
+	if r == nil || len(r.Comments) == 0 {
+		return []byte(`null`), nil
+	}
+	return json.Marshal(r.Comments)
+}
+
 // todo: should we implement json.Marshaler?
 
 // More holds information
@@ -381,7 +414,7 @@ type ModActions struct {
 type PostAndComments struct {
 	Post         *Post      `json:"post"`
 	Comments     []*Comment `json:"comments"`
-	moreComments *More
+	MoreComments *More      `json:"-"`
 }
 
 // UnmarshalJSON implements the json.Unmarshaler interface.
@@ -402,11 +435,33 @@ func (pc *PostAndComments) UnmarshalJSON(data []byte) error {
 
 	pc.Post = post
 	pc.Comments = comments
-	pc.moreComments = moreComments
+	pc.MoreComments = moreComments
 
 	return nil
 }
 
-func (pc *PostAndComments) hasMore() bool {
-	return pc.moreComments != nil && len(pc.moreComments.Children) > 0
+// HasMore determines whether the post has more replies to load in its reply tree.
+func (pc *PostAndComments) HasMore() bool {
+	return pc.MoreComments != nil && len(pc.MoreComments.Children) > 0
+}
+
+func (pc *PostAndComments) addCommentToTree(comment *Comment) {
+	if pc.Post.FullID == comment.ParentID {
+		pc.Comments = append(pc.Comments, comment)
+		return
+	}
+
+	for _, reply := range pc.Comments {
+		reply.addCommentToReplies(comment)
+	}
+}
+
+func (pc *PostAndComments) addMoreToTree(more *More) {
+	if pc.Post.FullID == more.ParentID {
+		pc.MoreComments = more
+	}
+
+	for _, reply := range pc.Comments {
+		reply.addMoreToReplies(more)
+	}
 }