DEV: Move solved custom fields into a table (#342)

Related: 
- https://github.com/discourse/discourse-solved/pull/309
- https://github.com/discourse/discourse-solved/pull/341

Requires:
- https://github.com/discourse/discourse/pull/31954

This commit converts all use of post and topic custom fields into a dedicated table:
- migration for copying custom field into table
- swap app usage of custom fields to table

This commit does not attempt to fix issues or optimise, and does not delete old data from custom fields _yet_.

.discourse-compatibility

@@ -1,3 +1,4 @@
+< 3.5.0.beta2-dev: e82c6ae1ca38ccebb34669148f8de93a3028906e
 < 3.5.0.beta1-dev: 5450a5ef4e2ae35185320fc6af9678621026e148
 < 3.4.0.beta4-dev: 3f724bf3114cc7877fa757bc8035f13a7390c739
 < 3.4.0.beta2-dev: 1bbdfd8f5681171dc3f0e9ea93cd56997dc7938a

app/models/discourse_solved/solved_topic.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module DiscourseSolved
+  class SolvedTopic < ActiveRecord::Base
+    self.table_name = "discourse_solved_solved_topics"
+
+    belongs_to :topic, class_name: "Topic"
+    belongs_to :answer_post, class_name: "Post", foreign_key: "answer_post_id"
+    belongs_to :accepter, class_name: "User", foreign_key: "accepter_user_id"
+    belongs_to :topic_timer
+
+    validates :topic_id, presence: true
+    validates :answer_post_id, presence: true
+    validates :accepter_user_id, presence: true
+  end
+end
+
+# == Schema Information
+#
+# Table name: discourse_solved_solved_topics
+#
+#  id               :bigint           not null, primary key
+#  topic_id         :integer          not null
+#  answer_post_id   :integer          not null
+#  accepter_user_id :integer          not null
+#  topic_timer_id   :integer
+#  created_at       :datetime         not null
+#  updated_at       :datetime         not null
+#
+# Indexes
+#
+#  index_discourse_solved_solved_topics_on_answer_post_id  (answer_post_id) UNIQUE
+#  index_discourse_solved_solved_topics_on_topic_id        (topic_id) UNIQUE
+#

app/serializers/concerns/discourse_solved/topic_answer_mixin.rb

@@ -7,7 +7,7 @@ module DiscourseSolved
     end
 
     def has_accepted_answer
-      object.custom_fields[::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD].present?
+      object&.solved.present?
     end
 
     def include_has_accepted_answer?

db/fixtures/001_badges.rb

@@ -3,14 +3,13 @@
 first_solution_query = <<~SQL
   SELECT post_id, user_id, created_at AS granted_at
   FROM (
-           SELECT p.id AS post_id, p.user_id, pcf.created_at,
+           SELECT p.id AS post_id, p.user_id, dsst.created_at,
-                  ROW_NUMBER() OVER (PARTITION BY p.user_id ORDER BY pcf.created_at) AS row_number
+              ROW_NUMBER() OVER (PARTITION BY p.user_id ORDER BY dsst.created_at) AS row_number
-           FROM post_custom_fields pcf
+           FROM discourse_solved_solved_topics dsst
-                JOIN badge_posts p ON pcf.post_id = p.id
+              JOIN badge_posts p ON dsst.answer_post_id = p.id
-                JOIN topics t ON p.topic_id = t.id
+              JOIN topics t ON p.topic_id = t.id
-           WHERE pcf.name = 'is_accepted_answer'
+           WHERE p.user_id <> t.user_id -- ignore topics solved by OP
-             AND p.user_id <> t.user_id -- ignore topics solved by OP
+              AND (:backfill OR p.id IN (:post_ids))
-             AND (:backfill OR p.id IN (:post_ids))
        ) x
   WHERE row_number = 1
 SQL
@@ -32,12 +31,11 @@ end
 
 def solved_query_with_count(min_count)
   <<~SQL
-    SELECT p.user_id, MAX(pcf.created_at) AS granted_at
+    SELECT p.user_id, MAX(dsst.created_at) AS granted_at
-    FROM post_custom_fields pcf
+    FROM discourse_solved_solved_topics dsst
-         JOIN badge_posts p ON pcf.post_id = p.id
+         JOIN badge_posts p ON dsst.answer_post_id = p.id
          JOIN topics t ON p.topic_id = t.id
-    WHERE pcf.name = 'is_accepted_answer'
+    WHERE p.user_id <> t.user_id -- ignore topics solved by OP
-      AND p.user_id <> t.user_id -- ignore topics solved by OP
       AND (:backfill OR p.id IN (:post_ids))
     GROUP BY p.user_id
     HAVING COUNT(*) >= #{min_count}

db/migrate/20250318024824_create_discourse_solved_solved_topics.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+#
+class CreateDiscourseSolvedSolvedTopics < ActiveRecord::Migration[7.2]
+  def change
+    create_table :discourse_solved_solved_topics do |t|
+      t.integer :topic_id, null: false
+      t.integer :answer_post_id, null: false
+      t.integer :accepter_user_id, null: false
+      t.integer :topic_timer_id
+      t.timestamps
+    end
+  end
+end

db/migrate/20250318024953_copy_solved_topic_custom_field_to_discourse_solved_solved_topics.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+#
+class CopySolvedTopicCustomFieldToDiscourseSolvedSolvedTopics < ActiveRecord::Migration[7.2]
+  disable_ddl_transaction!
+
+  BATCH_SIZE = 5000
+
+  def up
+    last_id = 0
+    loop do
+      rows = DB.query(<<~SQL, last_id: last_id, batch_size: BATCH_SIZE)
+        INSERT INTO discourse_solved_solved_topics (
+          topic_id,
+          answer_post_id,
+          topic_timer_id,
+          accepter_user_id,
+          created_at,
+          updated_at
+        )
+        SELECT DISTINCT ON (tc.topic_id)
+          tc.topic_id,
+          CAST(tc.value AS INTEGER),
+          CAST(tc2.value AS INTEGER),
+          COALESCE(ua.acting_user_id, -1),
+          tc.created_at,
+          tc.updated_at
+        FROM topic_custom_fields tc
+        LEFT JOIN topic_custom_fields tc2
+          ON tc2.topic_id = tc.topic_id
+          AND tc2.name = 'solved_auto_close_topic_timer_id'
+        LEFT JOIN user_actions ua
+          ON ua.target_topic_id = tc.topic_id
+          AND ua.action_type = 15
+        WHERE tc.name = 'accepted_answer_post_id'
+          AND tc.id > :last_id
+        ORDER BY tc.topic_id, ua.created_at DESC
+        LIMIT :batch_size
+      SQL
+
+      break if rows.length == 0
+      last_id += BATCH_SIZE
+    end
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration
+  end
+end

db/migrate/20250318025147_add_index_for_discourse_solved_topics.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+#
+class AddIndexForDiscourseSolvedTopics < ActiveRecord::Migration[7.2]
+  disable_ddl_transaction!
+
+  def change
+    remove_index :discourse_solved_solved_topics,
+                 :topic_id,
+                 algorithm: :concurrently,
+                 unique: true,
+                 if_exists: true
+    remove_index :discourse_solved_solved_topics,
+                 :answer_post_id,
+                 algorithm: :concurrently,
+                 unique: true,
+                 if_exists: true
+
+    add_index :discourse_solved_solved_topics, :topic_id, unique: true, algorithm: :concurrently
+    add_index :discourse_solved_solved_topics,
+              :answer_post_id,
+              unique: true,
+              algorithm: :concurrently
+  end
+end

lib/discourse_assign/entry_point.rb

@@ -2,15 +2,13 @@
 
 module DiscourseAssign
   class EntryPoint
+    # TODO: These four plugin api usages should ideally be in the assign plugin, not the solved plugin.
+    # They have been moved here from plugin.rb as part of the custom fields migration.
+
     def self.inject(plugin)
       plugin.register_modifier(:assigns_reminder_assigned_topics_query) do |query|
         next query if !SiteSetting.ignore_solved_topics_in_assigned_reminder
-        query.where.not(
+        query.where.not(id: DiscourseSolved::SolvedTopic.select(:topic_id))
-          id:
-            TopicCustomField.where(
-              name: ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD,
-            ).pluck(:topic_id),
-        )
       end
 
       plugin.register_modifier(:assigned_count_for_user_query) do |query, user|

lib/discourse_dev/discourse_solved.rb

@@ -11,24 +11,24 @@ module DiscourseDev
 
           solved_category =
             DiscourseDev::Record.random(
-              Category.where(
+              ::Category.where(
                 read_restricted: false,
                 id: records.pluck(:id),
                 parent_category_id: nil,
               ),
             )
-          CategoryCustomField.create!(
+          ::CategoryCustomField.create!(
             category_id: solved_category.id,
             name: ::DiscourseSolved::ENABLE_ACCEPTED_ANSWERS_CUSTOM_FIELD,
             value: "true",
           )
           puts "discourse-solved enabled on category '#{solved_category.name}' (#{solved_category.id})."
         elsif type == :topic
-          topics = Topic.where(id: records.pluck(:id))
+          topics = ::Topic.where(id: records.pluck(:id))
 
           unless SiteSetting.allow_solved_on_all_topics
             solved_category_id =
-              CategoryCustomField
+              ::CategoryCustomField
                 .where(name: ::DiscourseSolved::ENABLE_ACCEPTED_ANSWERS_CUSTOM_FIELD, value: "true")
                 .first
                 .category_id

lib/discourse_solved/before_head_close.rb

@@ -40,10 +40,7 @@ class DiscourseSolved::BeforeHeadClose
       },
     }
 
-    if accepted_answer =
+    if accepted_answer = topic.solved&.answer_post
-         Post.find_by(
-           id: topic.custom_fields[::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD],
-         )
       question_json["answerCount"] = 1
       question_json[:acceptedAnswer] = {
         "@type" => "Answer",

lib/discourse_solved/register_filters.rb

@@ -4,24 +4,16 @@ module DiscourseSolved
   class RegisterFilters
     def self.register(plugin)
       solved_callback = ->(scope) do
-        sql = <<~SQL
+        scope.joins(
-      topics.id IN (
+          "INNER JOIN discourse_solved_solved_topics ON discourse_solved_solved_topics.topic_id = topics.id",
-        SELECT topic_id
+        ).where("topics.archetype <> ?", Archetype.private_message)
-          FROM topic_custom_fields
-         WHERE name = '#{::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD}'
-           AND value IS NOT NULL
-      )
-    SQL
-
-        scope.where(sql).where("topics.archetype <> ?", Archetype.private_message)
       end
+
       unsolved_callback = ->(scope) do
-        scope = scope.where <<~SQL
+        scope = scope.where(<<~SQL)
           topics.id NOT IN (
             SELECT topic_id
-              FROM topic_custom_fields
+            FROM discourse_solved_solved_topics
-             WHERE name = '#{::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD}'
-               AND value IS NOT NULL
           )
         SQL
 
@@ -29,21 +21,21 @@ module DiscourseSolved
           tag_ids = Tag.where(name: SiteSetting.enable_solved_tags.split("|")).pluck(:id)
 
           scope = scope.where <<~SQL, tag_ids
-        topics.id IN (
+            topics.id IN (
-          SELECT t.id
+              SELECT t.id
-            FROM topics t
+                FROM topics t
-            JOIN category_custom_fields cc
+                JOIN category_custom_fields cc
-              ON t.category_id = cc.category_id
+                  ON t.category_id = cc.category_id
-             AND cc.name = '#{::DiscourseSolved::ENABLE_ACCEPTED_ANSWERS_CUSTOM_FIELD}'
+                 AND cc.name = '#{::DiscourseSolved::ENABLE_ACCEPTED_ANSWERS_CUSTOM_FIELD}'
-             AND cc.value = 'true'
+                 AND cc.value = 'true'
-        )
+            )
-        OR
+            OR
-        topics.id IN (
+            topics.id IN (
-          SELECT topic_id
+              SELECT topic_id
-            FROM topic_tags
+                FROM topic_tags
-           WHERE tag_id IN (?)
+               WHERE tag_id IN (?)
-        )
+            )
-      SQL
+          SQL
         end
 
         scope.where("topics.archetype <> ?", Archetype.private_message)

lib/discourse_solved/topic_extension.rb

@@ -0,0 +1,7 @@
+# frozen_string_literal: true
+
+module DiscourseSolved::TopicExtension
+  extend ActiveSupport::Concern
+
+  prepended { has_one :solved, class_name: "DiscourseSolved::SolvedTopic", dependent: :destroy }
+end

lib/discourse_solved/topic_view_serializer_extension.rb

@@ -43,12 +43,6 @@ module DiscourseSolved::TopicViewSerializerExtension
   end
 
   def accepted_answer_post_id
-    id = object.topic.custom_fields[::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD]
+    object.topic.solved&.answer_post_id
-    # a bit messy but race conditions can give us an array here, avoid
-    begin
-      id && id.to_i
-    rescue StandardError
-      nil
-    end
   end
 end

lib/discourse_solved/user_summary_extension.rb

@@ -4,6 +4,6 @@ module DiscourseSolved::UserSummaryExtension
   extend ActiveSupport::Concern
 
   def solved_count
-    UserAction.where(user: @user).where(action_type: UserAction::SOLVED).count
+    DiscourseSolved::SolvedTopic.where(accepter: @user).count
   end
 end

plugin.rb

@@ -18,10 +18,7 @@ register_asset "stylesheets/mobile/solutions.scss", :mobile
 
 module ::DiscourseSolved
   PLUGIN_NAME = "discourse-solved"
-  AUTO_CLOSE_TOPIC_TIMER_CUSTOM_FIELD = "solved_auto_close_topic_timer_id"
-  ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD = "accepted_answer_post_id"
   ENABLE_ACCEPTED_ANSWERS_CUSTOM_FIELD = "enable_accepted_answers"
-  IS_ACCEPTED_ANSWER_CUSTOM_FIELD = "is_accepted_answer"
 end
 
 require_relative "lib/discourse_solved/engine.rb"
@@ -34,27 +31,25 @@ after_initialize do
       topic ||= post.topic
 
       DistributedMutex.synchronize("discourse_solved_toggle_answer_#{topic.id}") do
-        accepted_id = topic.custom_fields[ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD].to_i
+        solved = topic.solved
 
-        if accepted_id > 0
+        if previous_accepted_post_id = solved&.answer_post_id
-          if p2 = Post.find_by(id: accepted_id)
+          UserAction.where(
-            p2.custom_fields.delete(IS_ACCEPTED_ANSWER_CUSTOM_FIELD)
+            action_type: UserAction::SOLVED,
-            p2.save!
+            target_post_id: previous_accepted_post_id,
-
+          ).destroy_all
-            UserAction.where(action_type: UserAction::SOLVED, target_post_id: p2.id).destroy_all
+        else
-          end
+          UserAction.log_action!(
+            action_type: UserAction::SOLVED,
+            user_id: post.user_id,
+            acting_user_id: acting_user.id,
+            target_post_id: post.id,
+            target_topic_id: post.topic_id,
+          )
         end
 
-        post.custom_fields[IS_ACCEPTED_ANSWER_CUSTOM_FIELD] = "true"
+        solved ||=
-        topic.custom_fields[ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD] = post.id
+          DiscourseSolved::SolvedTopic.new(topic:, answer_post: post, accepter: acting_user)
-
-        UserAction.log_action!(
-          action_type: UserAction::SOLVED,
-          user_id: post.user_id,
-          acting_user_id: acting_user.id,
-          target_post_id: post.id,
-          target_topic_id: post.topic_id,
-        )
 
         notification_data = {
           message: "solved.accepted_notification",
@@ -99,14 +94,12 @@ after_initialize do
               based_on_last_post: true,
               duration_minutes: auto_close_hours * 60,
             )
-
+          solved.topic_timer = topic_timer
-          topic.custom_fields[AUTO_CLOSE_TOPIC_TIMER_CUSTOM_FIELD] = topic_timer.id
 
           MessageBus.publish("/topic/#{topic.id}", reload_topic: true)
         end
 
-        topic.save!
+        solved.save!
-        post.save!
 
         if WebHook.active_web_hooks(:accepted_solution).exists?
           payload = WebHook.generate_payload(:post, post)
@@ -120,41 +113,28 @@ after_initialize do
     def self.unaccept_answer!(post, topic: nil)
       topic ||= post.topic
       topic ||= Topic.unscoped.find_by(id: post.topic_id)
-
       return if topic.nil?
+      return if topic.solved.nil?
 
       DistributedMutex.synchronize("discourse_solved_toggle_answer_#{topic.id}") do
-        post.custom_fields.delete(IS_ACCEPTED_ANSWER_CUSTOM_FIELD)
+        solved = topic.solved
-        topic.custom_fields.delete(ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD)
 
-        if timer_id = topic.custom_fields[AUTO_CLOSE_TOPIC_TIMER_CUSTOM_FIELD]
+        ActiveRecord::Base.transaction do
-          topic_timer = TopicTimer.find_by(id: timer_id)
+          UserAction.where(action_type: UserAction::SOLVED, target_post_id: post.id).destroy_all
-          topic_timer.destroy! if topic_timer
-          topic.custom_fields.delete(AUTO_CLOSE_TOPIC_TIMER_CUSTOM_FIELD)
-        end
-
-        topic.save!
-        post.save!
-
-        # TODO remove_action! does not allow for this type of interface
-        UserAction.where(action_type: UserAction::SOLVED, target_post_id: post.id).destroy_all
-
-        # yank notification
-        notification =
           Notification.find_by(
             notification_type: Notification.types[:custom],
             user_id: post.user_id,
             topic_id: post.topic_id,
             post_number: post.post_number,
-          )
+          )&.destroy!
-
+          solved.topic_timer.destroy! if solved.topic_timer
-        notification.destroy! if notification
+          solved.destroy!
+        end
 
         if WebHook.active_web_hooks(:unaccepted_solution).exists?
           payload = WebHook.generate_payload(:post, post)
           WebHook.enqueue_solved_hooks(:unaccepted_solution, post, payload)
         end
-
         DiscourseEvent.trigger(:unaccepted_solution, post)
       end
     end
@@ -168,6 +148,7 @@ after_initialize do
     ::Guardian.prepend(DiscourseSolved::GuardianExtensions)
     ::WebHook.prepend(DiscourseSolved::WebHookExtension)
     ::TopicViewSerializer.prepend(DiscourseSolved::TopicViewSerializerExtension)
+    ::Topic.prepend(DiscourseSolved::TopicExtension)
     ::Category.prepend(DiscourseSolved::CategoryExtension)
     ::PostSerializer.prepend(DiscourseSolved::PostSerializerExtension)
     ::UserSummary.prepend(DiscourseSolved::UserSummaryExtension)
@@ -183,49 +164,10 @@ after_initialize do
     ].each { |klass| klass.include(DiscourseSolved::TopicAnswerMixin) }
   end
 
-  # we got to do a one time upgrade
+  register_category_list_topics_preloader_associations(:solved) if SiteSetting.solved_enabled
-  if !::DiscourseSolved.skip_db?
+  register_topic_preloader_associations(:solved) if SiteSetting.solved_enabled
-    unless Discourse.redis.get("solved_already_upgraded")
+  Search.custom_topic_eager_load { [:solved] } if SiteSetting.solved_enabled
-      unless UserAction.where(action_type: UserAction::SOLVED).exists?
-        Rails.logger.info("Upgrading storage for solved")
-        sql = <<~SQL
-          INSERT INTO user_actions(action_type,
-                                   user_id,
-                                   target_topic_id,
-                                   target_post_id,
-                                   acting_user_id,
-                                   created_at,
-                                   updated_at)
-          SELECT :solved,
-                 p.user_id,
-                 p.topic_id,
-                 p.id,
-                 t.user_id,
-                 pc.created_at,
-                 pc.updated_at
-          FROM
-            post_custom_fields pc
-          JOIN
-            posts p ON p.id = pc.post_id
-          JOIN
-            topics t ON t.id = p.topic_id
-          WHERE
-            pc.name = 'is_accepted_answer' AND
-            pc.value = 'true' AND
-            p.user_id IS NOT NULL
-        SQL
-
-        DB.exec(sql, solved: UserAction::SOLVED)
-      end
-      Discourse.redis.set("solved_already_upgraded", "true")
-    end
-  end
-
-  topic_view_post_custom_fields_allowlister { [::DiscourseSolved::IS_ACCEPTED_ANSWER_CUSTOM_FIELD] }
-  TopicList.preloaded_custom_fields << ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD
   Site.preloaded_category_custom_fields << ::DiscourseSolved::ENABLE_ACCEPTED_ANSWERS_CUSTOM_FIELD
-  Search.preloaded_topic_custom_fields << ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD
-  CategoryList.preloaded_topic_custom_fields << ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD
 
   add_api_key_scope(
     :solved,
@@ -244,10 +186,10 @@ after_initialize do
     report.data = []
 
     accepted_solutions =
-      TopicCustomField
+      DiscourseSolved::SolvedTopic.joins(:topic).where(
-        .joins(:topic)
+        "topics.archetype <> ?",
-        .where("topics.archetype <> ?", Archetype.private_message)
+        Archetype.private_message,
-        .where(name: ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD)
+      )
 
     category_id, include_subcategories = report.add_category_filter
     if category_id
@@ -263,17 +205,17 @@ after_initialize do
     end
 
     accepted_solutions
-      .where("topic_custom_fields.created_at >= ?", report.start_date)
+      .where("discourse_solved_solved_topics.created_at >= ?", report.start_date)
-      .where("topic_custom_fields.created_at <= ?", report.end_date)
+      .where("discourse_solved_solved_topics.created_at <= ?", report.end_date)
-      .group("DATE(topic_custom_fields.created_at)")
+      .group("DATE(discourse_solved_solved_topics.created_at)")
-      .order("DATE(topic_custom_fields.created_at)")
+      .order("DATE(discourse_solved_solved_topics.created_at)")
       .count
       .each { |date, count| report.data << { x: date, y: count } }
     report.total = accepted_solutions.count
     report.prev30Days =
       accepted_solutions
-        .where("topic_custom_fields.created_at >= ?", report.start_date - 30.days)
+        .where("discourse_solved_solved_topics.created_at >= ?", report.start_date - 30.days)
-        .where("topic_custom_fields.created_at <= ?", report.start_date)
+        .where("discourse_solved_solved_topics.created_at <= ?", report.start_date)
         .count
   end
 
@@ -282,10 +224,8 @@ after_initialize do
       condition = <<~SQL
         EXISTS (
           SELECT 1
-            FROM topic_custom_fields
+            FROM discourse_solved_solved_topics
-           WHERE topic_id = topics.id
+           WHERE discourse_solved_solved_topics.topic_id = topics.id
-             AND name = '#{::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD}'
-             AND value IS NOT NULL
         )
       SQL
 
@@ -315,18 +255,10 @@ after_initialize do
   add_to_serializer(:post, :can_unaccept_answer) do
     scope.can_accept_answer?(topic, object) && accepted_answer
   end
-  add_to_serializer(:post, :accepted_answer) do
+  add_to_serializer(:post, :accepted_answer) { topic&.solved&.answer_post_id == object.id }
-    post_custom_fields[::DiscourseSolved::IS_ACCEPTED_ANSWER_CUSTOM_FIELD] == "true"
+  add_to_serializer(:post, :topic_accepted_answer) { topic&.solved&.present? }
-  end
-  add_to_serializer(:post, :topic_accepted_answer) do
-    topic&.custom_fields&.[](::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD).present?
-  end
 
-  on(:post_destroyed) do |post|
+  on(:post_destroyed) { |post| ::DiscourseSolved.unaccept_answer!(post) }
-    if post.custom_fields[::DiscourseSolved::IS_ACCEPTED_ANSWER_CUSTOM_FIELD] == "true"
-      ::DiscourseSolved.unaccept_answer!(post)
-    end
-  end
 
   on(:filter_auto_bump_topics) do |_category, filters|
     filters.push(
@@ -334,10 +266,8 @@ after_initialize do
         sql = <<~SQL
           NOT EXISTS (
             SELECT 1
-              FROM topic_custom_fields
+              FROM discourse_solved_solved_topics
-             WHERE topic_id = topics.id
+             WHERE discourse_solved_solved_topics.topic_id = topics.id
-               AND name = '#{::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD}'
-               AND value IS NOT NULL
           )
         SQL
 
@@ -390,7 +320,7 @@ after_initialize do
   add_to_class(:composer_messages_finder, :check_topic_is_solved) do
     return if !SiteSetting.solved_enabled || SiteSetting.disable_solved_education_message
     return if !replying? || @topic.blank? || @topic.private_message?
-    return if @topic.custom_fields[::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD].blank?
+    return if @topic.solved.nil?
 
     {
       id: "solved_topic",
@@ -402,15 +332,17 @@ after_initialize do
     }
   end
 
-  register_topic_list_preload_user_ids do |topics, user_ids, topic_list|
+  register_topic_list_preload_user_ids do |topics, user_ids|
-    answer_post_ids =
+    # [{ topic_id => answer_user_id }, ... ]
-      TopicCustomField
+    topics_with_answer_poster =
-        .select("value::INTEGER")
+      DiscourseSolved::SolvedTopic
-        .where(name: ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD)
+        .joins(:answer_post)
         .where(topic_id: topics.map(&:id))
-    answer_user_ids = Post.where(id: answer_post_ids).pluck(:topic_id, :user_id).to_h
+        .pluck(:topic_id, "posts.user_id")
-    topics.each { |topic| topic.accepted_answer_user_id = answer_user_ids[topic.id] }
+        .to_h
-    user_ids.concat(answer_user_ids.values)
+
+    topics.each { |topic| topic.accepted_answer_user_id = topics_with_answer_poster[topic.id] }
+    user_ids.concat(topics_with_answer_poster.values)
   end
 
   DiscourseSolved::RegisterFilters.register(self)

spec/fabricators/solved_topic_fabricator.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+Fabricator(:solved_topic, from: DiscourseSolved::SolvedTopic) do
+  topic
+  answer_post { Fabricate(:post) }
+  accepter { Fabricate(:user) }
+end

spec/integration/solved_spec.rb

@@ -30,31 +30,21 @@ RSpec.describe "Managing Posts solved status" do
     fab!(:solvable_tag) { Fabricate(:tag) }
 
     fab!(:solved_in_category) do
-      Fabricate(
+      topic = Fabricate(:topic, category: solvable_category)
-        :custom_topic,
+      Fabricate(:solved_topic, topic:, answer_post: Fabricate(:post, topic:))
-        category: solvable_category,
+      topic
-        custom_topic_name: ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD,
-        value: "42",
-      )
     end
 
     fab!(:solved_in_tag) do
-      Fabricate(
+      topic = Fabricate(:topic, tags: [solvable_tag])
-        :custom_topic,
+      Fabricate(:solved_topic, topic:, answer_post: Fabricate(:post, topic:))
-        tags: [solvable_tag],
+      topic
-        custom_topic_name: ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD,
-        value: "42",
-      )
     end
 
     fab!(:solved_pm) do
-      Fabricate(
+      topic = Fabricate(:topic, archetype: Archetype.private_message, category_id: nil)
-        :custom_topic,
+      Fabricate(:solved_topic, topic:, answer_post: Fabricate(:post, topic:))
-        category_id: nil,
+      topic
-        archetype: Archetype.private_message,
-        custom_topic_name: ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD,
-        value: "42",
-      )
     end
 
     fab!(:unsolved_in_category) { Fabricate(:topic, category: solvable_category) }
@@ -136,39 +126,15 @@ RSpec.describe "Managing Posts solved status" do
         category
       end
       fab!(:tag)
-      fab!(:topic_unsolved) do
+      fab!(:topic_unsolved) { Fabricate(:topic, user:, category: category_enabled) }
-        Fabricate(
-          :custom_topic,
-          user: user,
-          category: category_enabled,
-          custom_topic_name: ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD,
-        )
-      end
       fab!(:topic_unsolved_2) { Fabricate(:topic, user: user, tags: [tag]) }
       fab!(:topic_solved) do
-        Fabricate(
+        topic = Fabricate(:topic, category: category_enabled)
-          :custom_topic,
+        Fabricate(:solved_topic, topic:, answer_post: Fabricate(:post, topic:))
-          user: user,
+        topic
-          category: category_enabled,
-          custom_topic_name: ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD,
-        )
-      end
-      fab!(:topic_disabled_1) do
-        Fabricate(
-          :custom_topic,
-          user: user,
-          category: category_disabled,
-          custom_topic_name: ::DiscourseSolved::ACCEPTED_ANSWER_POST_ID_CUSTOM_FIELD,
-        )
-      end
-      fab!(:topic_disabled_2) do
-        Fabricate(
-          :custom_topic,
-          user: user,
-          category: category_disabled,
-          custom_topic_name: "another_custom_field",
-        )
       end
+      fab!(:topic_disabled_1) { Fabricate(:topic, category: category_disabled) }
+      fab!(:topic_disabled_2) { Fabricate(:topic, category: category_disabled) }
       fab!(:post_unsolved) { Fabricate(:post, topic: topic_unsolved) }
       fab!(:post_unsolved_2) { Fabricate(:post, topic: topic_unsolved_2) }
       fab!(:post_solved) do
@@ -258,18 +224,14 @@ RSpec.describe "Managing Posts solved status" do
       post "/solution/accept.json", params: { id: p1.id }
 
       expect(response.status).to eq(200)
-      expect(p1.reload.custom_fields["is_accepted_answer"]).to eq("true")
+      expect(topic.solved.answer_post_id).to eq(p1.id)
 
       topic.reload
 
       expect(topic.public_topic_timer.status_type).to eq(TopicTimer.types[:silent_close])
 
-      expect(topic.custom_fields["solved_auto_close_topic_timer_id"].to_i).to eq(
+      expect(topic.solved.topic_timer).to eq(topic.public_topic_timer)
-        topic.public_topic_timer.id,
-      )
-
       expect(topic.public_topic_timer.execute_at).to eq_time(Time.zone.now + 2.hours)
-
       expect(topic.public_topic_timer.based_on_last_post).to eq(true)
     end
 
@@ -284,18 +246,14 @@ RSpec.describe "Managing Posts solved status" do
       post "/solution/accept.json", params: { id: post_2.id }
 
       expect(response.status).to eq(200)
-      expect(post_2.reload.custom_fields["is_accepted_answer"]).to eq("true")
+      expect(topic_2.solved.answer_post_id).to eq(post_2.id)
 
       topic_2.reload
 
       expect(topic_2.public_topic_timer.status_type).to eq(TopicTimer.types[:silent_close])
 
-      expect(topic_2.custom_fields["solved_auto_close_topic_timer_id"].to_i).to eq(
+      expect(topic_2.solved.topic_timer).to eq(topic_2.public_topic_timer)
-        topic_2.public_topic_timer.id,
-      )
-
       expect(topic_2.public_topic_timer.execute_at).to eq_time(Time.zone.now + 4.hours)
-
       expect(topic_2.public_topic_timer.based_on_last_post).to eq(true)
     end
 
@@ -332,7 +290,7 @@ RSpec.describe "Managing Posts solved status" do
       p1.reload
       topic.reload
 
-      expect(p1.custom_fields["is_accepted_answer"]).to eq("true")
+      expect(topic.solved.answer_post_id).to eq(p1.id)
       expect(topic.public_topic_timer).to eq(nil)
       expect(topic.closed).to eq(true)
     end
@@ -348,7 +306,7 @@ RSpec.describe "Managing Posts solved status" do
       expect(response.status).to eq(200)
 
       p1.reload
-      expect(p1.custom_fields["is_accepted_answer"]).to eq("true")
+      expect(topic.solved.answer_post_id).to eq(p1.id)
     end
 
     it "removes the solution when the post is deleted" do
@@ -357,15 +315,12 @@ RSpec.describe "Managing Posts solved status" do
       post "/solution/accept.json", params: { id: reply.id }
       expect(response.status).to eq(200)
 
-      reply.reload
+      expect(topic.solved.answer_post_id).to eq(reply.id)
-      expect(reply.custom_fields["is_accepted_answer"]).to eq("true")
-      expect(reply.topic.custom_fields["accepted_answer_post_id"].to_i).to eq(reply.id)
 
       PostDestroyer.new(Discourse.system_user, reply).destroy
+      reply.topic.reload
 
-      reply.reload
+      expect(topic.solved).to be(nil)
-      expect(reply.custom_fields["is_accepted_answer"]).to eq(nil)
-      expect(reply.topic.custom_fields["accepted_answer_post_id"]).to eq(nil)
     end
 
     it "does not allow you to accept a whisper" do
@@ -395,6 +350,7 @@ RSpec.describe "Managing Posts solved status" do
       before do
         SiteSetting.solved_topics_auto_close_hours = 2
         DiscourseSolved.accept_answer!(p1, user)
+        topic.reload
       end
 
       it "should unmark the post as solved" do
@@ -405,12 +361,13 @@ RSpec.describe "Managing Posts solved status" do
         expect(response.status).to eq(200)
         p1.reload
 
-        expect(p1.custom_fields["is_accepted_answer"]).to eq(nil)
+        expect(topic.solved).to be(nil)
-        expect(p1.topic.custom_fields["accepted_answer_post_id"]).to eq(nil)
       end
     end
 
     it "triggers a webhook" do
+      DiscourseSolved.accept_answer!(p1, user)
+
       Fabricate(:solved_web_hook)
       post "/solution/unaccept.json", params: { id: p1.id }
 
@@ -466,8 +423,9 @@ RSpec.describe "Managing Posts solved status" do
 
         expect(p1.topic.assignment.status).to eq("New")
         DiscourseSolved.accept_answer!(p1, user)
+        topic.reload
 
-        expect(p1.reload.custom_fields["is_accepted_answer"]).to eq("true")
+        expect(topic.solved.answer_post_id).to eq(p1.id)
         expect(p1.topic.assignment.reload.status).to eq("Done")
       end
 
@@ -482,7 +440,6 @@ RSpec.describe "Managing Posts solved status" do
 
         DiscourseSolved.unaccept_answer!(p1)
 
-        expect(p1.reload.custom_fields["is_accepted_answer"]).to eq(nil)
         expect(p1.reload.topic.assignment.reload.status).to eq("New")
       end
 

spec/requests/topics_controller_spec.rb

@@ -45,10 +45,7 @@ RSpec.describe TopicsController do
 
       expect(response.body).to include(schema_json(0))
 
-      p2.custom_fields["is_accepted_answer"] = true
+      Fabricate(:solved_topic, topic: topic, answer_post: p2)
-      p2.save_custom_fields
-      topic.custom_fields["accepted_answer_post_id"] = p2.id
-      topic.save_custom_fields
 
       get "/t/#{topic.slug}/#{topic.id}"
 
@@ -68,10 +65,7 @@ RSpec.describe TopicsController do
 
     it "should include user name in output with the corresponding site setting" do
       SiteSetting.display_name_on_posts = true
-      p2.custom_fields["is_accepted_answer"] = true
+      Fabricate(:solved_topic, topic: topic, answer_post: p2)
-      p2.save_custom_fields
-      topic.custom_fields["accepted_answer_post_id"] = p2.id
-      topic.save_custom_fields
 
       get "/t/#{topic.slug}/#{topic.id}.json"
 
@@ -87,10 +81,7 @@ RSpec.describe TopicsController do
 
     it "should not include user name when site setting is disabled" do
       SiteSetting.display_name_on_posts = false
-      p2.custom_fields["is_accepted_answer"] = true
+      Fabricate(:solved_topic, topic: topic, answer_post: p2)
-      p2.save_custom_fields
-      topic.custom_fields["accepted_answer_post_id"] = p2.id
-      topic.save_custom_fields
 
       get "/t/#{topic.slug}/#{topic.id}.json"
 
@@ -106,10 +97,7 @@ RSpec.describe TopicsController do
 
     it "includes the correct schema information" do
       DiscourseTagging.add_or_create_tags_by_name(topic, [tag.name])
-      p2.custom_fields["is_accepted_answer"] = true
+      Fabricate(:solved_topic, topic: topic, answer_post: p2)
-      p2.save_custom_fields
-      topic.custom_fields["accepted_answer_post_id"] = p2.id
-      topic.save_custom_fields
 
       get "/t/#{topic.slug}/#{topic.id}"
 
@@ -120,10 +108,7 @@ RSpec.describe TopicsController do
       another_tag = Fabricate(:tag)
 
       DiscourseTagging.add_or_create_tags_by_name(topic, [another_tag.name])
-      p2.custom_fields["is_accepted_answer"] = true
+      Fabricate(:solved_topic, topic: topic, answer_post: p2)
-      p2.save_custom_fields
-      topic.custom_fields["accepted_answer_post_id"] = p2.id
-      topic.save_custom_fields
 
       get "/t/#{topic.slug}/#{topic.id}"
 

spec/serializers/topic_answer_mixin_spec.rb

@@ -7,10 +7,7 @@ describe DiscourseSolved::TopicAnswerMixin do
   let(:post) { Fabricate(:post, topic: topic) }
   let(:guardian) { Guardian.new }
 
-  before do
+  before { Fabricate(:solved_topic, topic: topic, answer_post: post) }
-    topic.custom_fields["accepted_answer_post_id"] = post.id
-    topic.save_custom_fields
-  end
 
   it "should have true for `has_accepted_answer` field in each serializer" do
     [

spec/serializers/user_card_serializer_spec.rb

@@ -12,6 +12,7 @@ describe UserCardSerializer do
 
     post1 = Fabricate(:post, user: user)
     DiscourseSolved.accept_answer!(post1, Discourse.system_user)
+    post1.topic.reload
     expect(serializer.as_json[:accepted_answers]).to eq(1)
 
     post2 = Fabricate(:post, user: user)