Update comments triggers to handle removals

Well, this alembic migration was a gigantic pain in the ass. Might be
worth writing a tool to be able to deal with things like this.

tildes/alembic/versions/fab922a8bb04_update_comment_triggers_for_removals.py

@@ -0,0 +1,328 @@
+"""Update comment triggers for removals
+
+Revision ID: fab922a8bb04
+Revises: f1ecbf24c212
+Create Date: 2018-08-09 00:56:40.718440
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = 'fab922a8bb04'
+down_revision = 'f1ecbf24c212'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # comment_notifications
+    op.execute("DROP TRIGGER delete_comment_notifications_update ON comments")
+    op.execute("""
+        CREATE TRIGGER delete_comment_notifications_update
+            AFTER UPDATE ON comments
+            FOR EACH ROW
+            WHEN ((OLD.is_deleted = false AND NEW.is_deleted = true)
+                OR (OLD.is_removed = false AND NEW.is_removed = true))
+            EXECUTE PROCEDURE delete_comment_notifications();
+    """)
+
+    # comments
+    op.execute("""
+        CREATE OR REPLACE FUNCTION set_comment_deleted_time() RETURNS TRIGGER AS $$
+        BEGIN
+            IF (NEW.is_deleted = TRUE) THEN
+                NEW.deleted_time := current_timestamp;
+            ELSE
+                NEW.deleted_time := NULL;
+            END IF;
+
+            RETURN NEW;
+        END;
+        $$ LANGUAGE plpgsql;
+    """)
+    op.execute("DROP TRIGGER delete_comment_set_deleted_time_update ON comments")
+    op.execute("""
+        CREATE TRIGGER delete_comment_set_deleted_time_update
+            BEFORE UPDATE ON comments
+            FOR EACH ROW
+            WHEN (OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
+            EXECUTE PROCEDURE set_comment_deleted_time();
+    """)
+
+    op.execute("""
+        CREATE OR REPLACE FUNCTION set_comment_removed_time() RETURNS TRIGGER AS $$
+        BEGIN
+            IF (NEW.is_removed = TRUE) THEN
+                NEW.removed_time := current_timestamp;
+            ELSE
+                NEW.removed_time := NULL;
+            END IF;
+
+            RETURN NEW;
+        END;
+        $$ LANGUAGE plpgsql;
+    """)
+    op.execute("""
+        CREATE TRIGGER remove_comment_set_removed_time_update
+            BEFORE UPDATE ON comments
+            FOR EACH ROW
+            WHEN (OLD.is_removed IS DISTINCT FROM NEW.is_removed)
+            EXECUTE PROCEDURE set_comment_removed_time();
+    """)
+
+    # topic_visits
+    op.execute("DROP TRIGGER update_topic_visits_num_comments_update ON comments")
+    op.execute("DROP FUNCTION decrement_all_topic_visit_num_comments()")
+    op.execute("""
+        CREATE OR REPLACE FUNCTION update_all_topic_visit_num_comments() RETURNS TRIGGER AS $$
+        DECLARE
+            old_visible BOOLEAN := NOT (OLD.is_deleted OR OLD.is_removed);
+            new_visible BOOLEAN := NOT (NEW.is_deleted OR NEW.is_removed);
+        BEGIN
+            IF (old_visible AND NOT new_visible) THEN
+                UPDATE topic_visits
+                    SET num_comments = num_comments - 1
+                    WHERE topic_id = OLD.topic_id AND
+                        visit_time > OLD.created_time;
+            ELSIF (NOT old_visible AND new_visible) THEN
+                UPDATE topic_visits
+                    SET num_comments = num_comments + 1
+                    WHERE topic_id = OLD.topic_id AND
+                        visit_time > OLD.created_time;
+            END IF;
+
+            RETURN NULL;
+        END;
+        $$ LANGUAGE plpgsql;
+    """)
+    op.execute("""
+        CREATE TRIGGER update_topic_visits_num_comments_update
+            AFTER UPDATE ON comments
+            FOR EACH ROW
+            WHEN ((OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
+                OR (OLD.is_removed IS DISTINCT FROM NEW.is_removed))
+            EXECUTE PROCEDURE update_all_topic_visit_num_comments();
+    """)
+
+    # topics
+    op.execute("""
+        CREATE OR REPLACE FUNCTION update_topics_num_comments() RETURNS TRIGGER AS $$
+        BEGIN
+            IF (TG_OP = 'INSERT') THEN
+                UPDATE topics
+                    SET num_comments = num_comments + 1
+                    WHERE topic_id = NEW.topic_id;
+            ELSIF (TG_OP = 'DELETE'
+                    AND OLD.is_deleted = FALSE
+                    AND OLD.is_removed = FALSE) THEN
+                UPDATE topics
+                    SET num_comments = num_comments - 1
+                    WHERE topic_id = OLD.topic_id;
+            ELSIF (TG_OP = 'UPDATE') THEN
+                DECLARE
+                    old_visible BOOLEAN := NOT (OLD.is_deleted OR OLD.is_removed);
+                    new_visible BOOLEAN := NOT (NEW.is_deleted OR NEW.is_removed);
+                BEGIN
+                    IF (old_visible AND NOT new_visible) THEN
+                        UPDATE topics
+                            SET num_comments = num_comments - 1
+                            WHERE topic_id = NEW.topic_id;
+                    ELSIF (NOT old_visible AND new_visible) THEN
+                        UPDATE topics
+                            SET num_comments = num_comments + 1
+                            WHERE topic_id = NEW.topic_id;
+                    END IF;
+                END;
+            END IF;
+
+            RETURN NULL;
+        END;
+        $$ LANGUAGE plpgsql;
+    """)
+    op.execute("DROP TRIGGER update_topics_num_comments_update ON comments")
+    op.execute("""
+        CREATE TRIGGER update_topics_num_comments_update
+            AFTER UPDATE ON comments
+            FOR EACH ROW
+            WHEN ((OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
+                OR (OLD.is_removed IS DISTINCT FROM NEW.is_removed))
+            EXECUTE PROCEDURE update_topics_num_comments();
+    """)
+
+    op.execute("""
+        CREATE OR REPLACE FUNCTION update_topics_last_activity_time() RETURNS TRIGGER AS $$
+        DECLARE
+            most_recent_comment RECORD;
+        BEGIN
+            IF (TG_OP = 'INSERT') THEN
+                UPDATE topics
+                    SET last_activity_time = NOW()
+                    WHERE topic_id = NEW.topic_id;
+            ELSIF (TG_OP = 'UPDATE') THEN
+                SELECT MAX(created_time) AS max_created_time
+                INTO most_recent_comment
+                FROM comments
+                WHERE topic_id = NEW.topic_id
+                    AND is_deleted = FALSE
+                    AND is_removed = FALSE;
+
+                IF most_recent_comment.max_created_time IS NOT NULL THEN
+                    UPDATE topics
+                        SET last_activity_time = most_recent_comment.max_created_time
+                        WHERE topic_id = NEW.topic_id;
+                ELSE
+                    UPDATE topics
+                        SET last_activity_time = created_time
+                        WHERE topic_id = NEW.topic_id;
+                END IF;
+            END IF;
+
+            RETURN NULL;
+        END;
+        $$ LANGUAGE plpgsql;
+    """)
+    op.execute("DROP TRIGGER update_topics_last_activity_time_update ON comments")
+    op.execute("""
+        CREATE TRIGGER update_topics_last_activity_time_update
+            AFTER UPDATE ON comments
+            FOR EACH ROW
+            WHEN ((OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
+                OR (OLD.is_removed IS DISTINCT FROM NEW.is_removed))
+            EXECUTE PROCEDURE update_topics_last_activity_time();
+    """)
+
+
+def downgrade():
+    # comment_notifications
+    op.execute("DROP TRIGGER delete_comment_notifications_update ON comments")
+    op.execute("""
+        CREATE TRIGGER delete_comment_notifications_update
+            AFTER UPDATE ON comments
+            FOR EACH ROW
+            WHEN (OLD.is_deleted = false AND NEW.is_deleted = true)
+            EXECUTE PROCEDURE delete_comment_notifications();
+    """)
+
+    # comments
+    op.execute("""
+        CREATE OR REPLACE FUNCTION set_comment_deleted_time() RETURNS TRIGGER AS $$
+        BEGIN
+            NEW.deleted_time := current_timestamp;
+
+            RETURN NEW;
+        END;
+        $$ LANGUAGE plpgsql;
+    """)
+    op.execute("DROP TRIGGER delete_comment_set_deleted_time_update ON comments")
+    op.execute("""
+        CREATE TRIGGER delete_comment_set_deleted_time_update
+            BEFORE UPDATE ON comments
+            FOR EACH ROW
+            WHEN (OLD.is_deleted = false AND NEW.is_deleted = true)
+            EXECUTE PROCEDURE set_comment_deleted_time();
+    """)
+
+    op.execute("DROP TRIGGER remove_comment_set_removed_time_update ON comments")
+    op.execute("DROP FUNCTION set_comment_removed_time()")
+
+    # topic_visits
+    op.execute("DROP TRIGGER update_topic_visits_num_comments_update ON comments")
+    op.execute("DROP FUNCTION update_all_topic_visit_num_comments()")
+    op.execute("""
+        CREATE OR REPLACE FUNCTION decrement_all_topic_visit_num_comments() RETURNS TRIGGER AS $$
+        BEGIN
+            UPDATE topic_visits
+                SET num_comments = num_comments - 1
+                WHERE topic_id = OLD.topic_id AND
+                    visit_time > OLD.created_time;
+
+            RETURN NULL;
+        END;
+        $$ LANGUAGE plpgsql;
+    """)
+    op.execute("""
+        CREATE TRIGGER update_topic_visits_num_comments_update
+            AFTER UPDATE ON comments
+            FOR EACH ROW
+            WHEN (OLD.is_deleted = false AND NEW.is_deleted = true)
+            EXECUTE PROCEDURE decrement_all_topic_visit_num_comments();
+    """)
+
+    # topics
+    op.execute("""
+        CREATE OR REPLACE FUNCTION update_topics_num_comments() RETURNS TRIGGER AS $$
+        BEGIN
+            IF (TG_OP = 'INSERT' AND NEW.is_deleted = FALSE) THEN
+                UPDATE topics
+                    SET num_comments = num_comments + 1
+                    WHERE topic_id = NEW.topic_id;
+            ELSIF (TG_OP = 'DELETE' AND OLD.is_deleted = FALSE) THEN
+                UPDATE topics
+                    SET num_comments = num_comments - 1
+                    WHERE topic_id = OLD.topic_id;
+            ELSIF (TG_OP = 'UPDATE') THEN
+                IF (OLD.is_deleted = FALSE AND NEW.is_deleted = TRUE) THEN
+                    UPDATE topics
+                        SET num_comments = num_comments - 1
+                        WHERE topic_id = NEW.topic_id;
+                ELSIF (OLD.is_deleted = TRUE AND NEW.is_deleted = FALSE) THEN
+                    UPDATE topics
+                        SET num_comments = num_comments + 1
+                        WHERE topic_id = NEW.topic_id;
+                END IF;
+            END IF;
+
+            RETURN NULL;
+        END;
+        $$ LANGUAGE plpgsql;
+    """)
+    op.execute("DROP TRIGGER update_topics_num_comments_update ON comments")
+    op.execute("""
+        CREATE TRIGGER update_topics_num_comments_update
+            AFTER UPDATE ON comments
+            FOR EACH ROW
+            WHEN (OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
+            EXECUTE PROCEDURE update_topics_num_comments();
+    """)
+
+    op.execute("""
+        CREATE OR REPLACE FUNCTION update_topics_last_activity_time() RETURNS TRIGGER AS $$
+        DECLARE
+            most_recent_comment RECORD;
+        BEGIN
+            IF (TG_OP = 'INSERT' AND NEW.is_deleted = FALSE) THEN
+                UPDATE topics
+                    SET last_activity_time = NOW()
+                    WHERE topic_id = NEW.topic_id;
+            ELSIF (TG_OP = 'UPDATE') THEN
+                SELECT MAX(created_time) AS max_created_time
+                INTO most_recent_comment
+                FROM comments
+                WHERE topic_id = NEW.topic_id AND
+                    is_deleted = FALSE;
+
+                IF most_recent_comment.max_created_time IS NOT NULL THEN
+                    UPDATE topics
+                        SET last_activity_time = most_recent_comment.max_created_time
+                        WHERE topic_id = NEW.topic_id;
+                ELSE
+                    UPDATE topics
+                        SET last_activity_time = created_time
+                        WHERE topic_id = NEW.topic_id;
+                END IF;
+            END IF;
+
+            RETURN NULL;
+        END;
+        $$ LANGUAGE plpgsql;
+    """)
+    op.execute("DROP TRIGGER update_topics_last_activity_time_update ON comments")
+    op.execute("""
+        CREATE TRIGGER update_topics_last_activity_time_update
+            AFTER UPDATE ON comments
+            FOR EACH ROW
+            WHEN (OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
+            EXECUTE PROCEDURE update_topics_last_activity_time();
+    """)

tildes/sql/init/triggers/comments/comment_notifications.sql

@@ -1,4 +1,4 @@
--- delete any comment notifications related to a comment when it's deleted
+-- delete any notifications related to a comment when it's deleted or removed
 CREATE OR REPLACE FUNCTION delete_comment_notifications() RETURNS TRIGGER AS $$
 BEGIN
     DELETE FROM comment_notifications
@@ -11,5 +11,6 @@ $$ LANGUAGE plpgsql;
 CREATE TRIGGER delete_comment_notifications_update
     AFTER UPDATE ON comments
     FOR EACH ROW
-    WHEN (OLD.is_deleted = false AND NEW.is_deleted = true)
+    WHEN ((OLD.is_deleted = false AND NEW.is_deleted = true)
+        OR (OLD.is_removed = false AND NEW.is_removed = true))
     EXECUTE PROCEDURE delete_comment_notifications();

tildes/sql/init/triggers/comments/comments.sql

@@ -1,7 +1,11 @@
--- set comment.deleted_time when it's deleted
+-- set comment.deleted_time when is_deleted changes
 CREATE OR REPLACE FUNCTION set_comment_deleted_time() RETURNS TRIGGER AS $$
 BEGIN
+    IF (NEW.is_deleted = TRUE) THEN
         NEW.deleted_time := current_timestamp;
+    ELSE
+        NEW.deleted_time := NULL;
+    END IF;
 
     RETURN NEW;
 END;
@@ -10,5 +14,25 @@ $$ LANGUAGE plpgsql;
 CREATE TRIGGER delete_comment_set_deleted_time_update
     BEFORE UPDATE ON comments
     FOR EACH ROW
-    WHEN (OLD.is_deleted = false AND NEW.is_deleted = true)
+    WHEN (OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
     EXECUTE PROCEDURE set_comment_deleted_time();
+
+
+-- set comment.removed_time when is_removed changes
+CREATE OR REPLACE FUNCTION set_comment_removed_time() RETURNS TRIGGER AS $$
+BEGIN
+    IF (NEW.is_removed = TRUE) THEN
+        NEW.removed_time := current_timestamp;
+    ELSE
+        NEW.removed_time := NULL;
+    END IF;
+
+    RETURN NEW;
+END;
+$$ LANGUAGE plpgsql;
+
+CREATE TRIGGER remove_comment_set_removed_time_update
+    BEFORE UPDATE ON comments
+    FOR EACH ROW
+    WHEN (OLD.is_removed IS DISTINCT FROM NEW.is_removed)
+    EXECUTE PROCEDURE set_comment_removed_time();

tildes/sql/init/triggers/comments/topic_visits.sql

@@ -16,13 +16,23 @@ CREATE TRIGGER update_topic_visits_num_comments_insert
     EXECUTE PROCEDURE increment_user_topic_visit_num_comments();
 
 
--- decrement all users' topic visit comment counts when a comment is deleted
-CREATE OR REPLACE FUNCTION decrement_all_topic_visit_num_comments() RETURNS TRIGGER AS $$
+-- adjust all users' topic visit comment counts when a comment is deleted/removed
+CREATE OR REPLACE FUNCTION update_all_topic_visit_num_comments() RETURNS TRIGGER AS $$
+DECLARE
+    old_visible BOOLEAN := NOT (OLD.is_deleted OR OLD.is_removed);
+    new_visible BOOLEAN := NOT (NEW.is_deleted OR NEW.is_removed);
 BEGIN
+    IF (old_visible AND NOT new_visible) THEN
         UPDATE topic_visits
             SET num_comments = num_comments - 1
             WHERE topic_id = OLD.topic_id AND
                 visit_time > OLD.created_time;
+    ELSIF (NOT old_visible AND new_visible) THEN
+        UPDATE topic_visits
+            SET num_comments = num_comments + 1
+            WHERE topic_id = OLD.topic_id AND
+                visit_time > OLD.created_time;
+    END IF;
 
     RETURN NULL;
 END;
@@ -31,5 +41,6 @@ $$ LANGUAGE plpgsql;
 CREATE TRIGGER update_topic_visits_num_comments_update
     AFTER UPDATE ON comments
     FOR EACH ROW
-    WHEN (OLD.is_deleted = false AND NEW.is_deleted = true)
-    EXECUTE PROCEDURE decrement_all_topic_visit_num_comments();
+    WHEN ((OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
+        OR (OLD.is_removed IS DISTINCT FROM NEW.is_removed))
+    EXECUTE PROCEDURE update_all_topic_visit_num_comments();

tildes/sql/init/triggers/comments/topics.sql

@@ -1,23 +1,30 @@
 CREATE OR REPLACE FUNCTION update_topics_num_comments() RETURNS TRIGGER AS $$
 BEGIN
-    IF (TG_OP = 'INSERT' AND NEW.is_deleted = FALSE) THEN
+    IF (TG_OP = 'INSERT') THEN
         UPDATE topics
             SET num_comments = num_comments + 1
             WHERE topic_id = NEW.topic_id;
-    ELSIF (TG_OP = 'DELETE' AND OLD.is_deleted = FALSE) THEN
+    ELSIF (TG_OP = 'DELETE'
+            AND OLD.is_deleted = FALSE
+            AND OLD.is_removed = FALSE) THEN
         UPDATE topics
             SET num_comments = num_comments - 1
             WHERE topic_id = OLD.topic_id;
     ELSIF (TG_OP = 'UPDATE') THEN
-        IF (OLD.is_deleted = FALSE AND NEW.is_deleted = TRUE) THEN
+        DECLARE
+            old_visible BOOLEAN := NOT (OLD.is_deleted OR OLD.is_removed);
+            new_visible BOOLEAN := NOT (NEW.is_deleted OR NEW.is_removed);
+        BEGIN
+            IF (old_visible AND NOT new_visible) THEN
                 UPDATE topics
                     SET num_comments = num_comments - 1
                     WHERE topic_id = NEW.topic_id;
-        ELSIF (OLD.is_deleted = TRUE AND NEW.is_deleted = FALSE) THEN
+            ELSIF (NOT old_visible AND new_visible) THEN
                 UPDATE topics
                     SET num_comments = num_comments + 1
                     WHERE topic_id = NEW.topic_id;
             END IF;
+        END;
     END IF;
 
     RETURN NULL;
@@ -32,20 +39,21 @@ CREATE TRIGGER update_topics_num_comments_insert_delete
     EXECUTE PROCEDURE update_topics_num_comments();
 
 
--- update trigger only needs to execute if is_deleted was changed
+-- update trigger only needs to execute if is_deleted or is_removed was changed
 CREATE TRIGGER update_topics_num_comments_update
     AFTER UPDATE ON comments
     FOR EACH ROW
-    WHEN (OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
+    WHEN ((OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
+        OR (OLD.is_removed IS DISTINCT FROM NEW.is_removed))
     EXECUTE PROCEDURE update_topics_num_comments();
 
 
--- update a topic's last activity time when a comment is posted or deleted
+-- update a topic's last activity time when a comment is posted, deleted, or removed
 CREATE OR REPLACE FUNCTION update_topics_last_activity_time() RETURNS TRIGGER AS $$
 DECLARE
     most_recent_comment RECORD;
 BEGIN
-    IF (TG_OP = 'INSERT' AND NEW.is_deleted = FALSE) THEN
+    IF (TG_OP = 'INSERT') THEN
         UPDATE topics
             SET last_activity_time = NOW()
             WHERE topic_id = NEW.topic_id;
@@ -53,8 +61,9 @@ BEGIN
         SELECT MAX(created_time) AS max_created_time
         INTO most_recent_comment
         FROM comments
-        WHERE topic_id = NEW.topic_id AND
-            is_deleted = FALSE;
+        WHERE topic_id = NEW.topic_id
+            AND is_deleted = FALSE
+            AND is_removed = FALSE;
 
         IF most_recent_comment.max_created_time IS NOT NULL THEN
             UPDATE topics
@@ -79,5 +88,6 @@ CREATE TRIGGER update_topics_last_activity_time_insert
 CREATE TRIGGER update_topics_last_activity_time_update
     AFTER UPDATE ON comments
     FOR EACH ROW
-    WHEN (OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
+    WHEN ((OLD.is_deleted IS DISTINCT FROM NEW.is_deleted)
+        OR (OLD.is_removed IS DISTINCT FROM NEW.is_removed))
     EXECUTE PROCEDURE update_topics_last_activity_time();

tildes/tildes/models/comment/comment.py

@@ -39,21 +39,23 @@ class Comment(DatabaseModel):
         - num_votes will be incremented and decremented by insertions and
           deletions in comment_votes.
       Outgoing:
-        - Inserting, deleting, or updating is_deleted will increment or
-          decrement num_comments on the relevant topic.
+        - Inserting or deleting rows, or updating is_deleted/is_removed to
+          change visibility will increment or decrement num_comments
+          accordingly on the relevant topic.
         - Inserting a row will increment num_comments on any topic_visit rows
           for the comment's author and the relevant topic.
-        - Inserting or updating is_deleted will update last_activity_time on
-          the relevant topic.
-        - Setting is_deleted to true will delete any rows in
+        - Inserting a new comment or updating is_deleted or is_removed will
+          update last_activity_time on the relevant topic.
+        - Setting is_deleted or is_removed to true will delete any rows in
           comment_notifications related to the comment.
-        - Setting is_deleted to true will decrement num_comments on all
+        - Changing is_deleted or is_removed will adjust num_comments on all
           topic_visit rows for the relevant topic, where the visit_time was
           after the time the comment was originally posted.
         - Inserting a row or updating markdown will send a rabbitmq message
           for "comment.created" or "comment.edited" respectively.
       Internal:
-        - deleted_time will be set when is_deleted is set to true
+        - deleted_time will be set or unset when is_deleted is changed
+        - removed_time will be set or unset when is_removed is changed
     """
 
     schema_class = CommentSchema