Refactor Talk indexing into a Talk::Index record.

app/models/active_record/sqlite/index.rb

@@ -0,0 +1,22 @@
+module ActiveRecord::SQLite::Index
+  extend ActiveSupport::Concern
+
+  included do
+    self.ignored_columns = [table_name.to_sym, :rank] # Rails parses our virtual table with these extra non-attributes.
+
+    attribute :rowid, :integer
+    alias_attribute :id, :rowid
+    self.primary_key = :rowid
+
+    # Active Record doesn't pick up the `rowid` primary key column.
+    # So we have have explicitly declare this scope to have `rowid` populated in the result set.
+    default_scope { select("#{table_name}.rowid, #{table_name}.*") }
+  end
+
+  private
+
+  def attributes_for_create(attribute_names)
+    # Prevent `super` filtering out the primary key because it isn't in `self.class.column_names`.
+    [self.class.primary_key, *super]
+  end
+end

app/models/talk/index.rb

@@ -0,0 +1,27 @@
+class Talk::Index < ApplicationRecord
+  self.table_name = :talks_search_index
+
+  include ActiveRecord::SQLite::Index # Depends on `table_name` being assigned.
+  class_attribute :index_columns, default: {title: 0, summary: 1, speaker_names: 2}
+
+  belongs_to :talk, foreign_key: :rowid
+
+  def self.search(query)
+    query = query&.gsub(/[^[:word:]]/, " ") || "" # remove non-word characters
+    query = query.split.map { |word| "#{word}*" }.join(" ") # wildcard search
+    where("#{table_name} match ?", query)
+  end
+
+  def self.snippets(**)
+    index_columns.each_key.reduce(all) { |relation, column| relation.snippet(column, **) }
+  end
+
+  def self.snippet(column, tag: "mark", omission: "…", limit: 32)
+    offset = index_columns.fetch(column)
+    select("snippet(#{table_name}, #{offset}, '<#{tag}>', '</#{tag}>', '#{omission}', #{limit}) AS #{column}_snippet")
+  end
+
+  def reindex
+    update! id: talk.id, title: talk.title, summary: talk.summary, speaker_names: talk.speaker_names
+  end
+end

app/models/talk/searchable.rb

@@ -4,62 +4,36 @@ module Talk::Searchable
   DATE_WEIGHT = 0.000000001
 
   included do
-    scope :ft_search, ->(query) do
-      query = query&.gsub(/[^[:word:]]/, " ") || "" # remove non-word characters
-      query = query.split.map { |word| "#{word}*" }.join(" ") # wildcard search
-      joins("join talks_search_index idx on talks.id = idx.rowid")
-        .where("talks_search_index match ?", query)
-    end
+    has_one :index, foreign_key: :rowid, inverse_of: :talk, dependent: :destroy
+
+    scope :ft_search, ->(query) { select("talks.*").joins(:index).merge(Talk::Index.search(query)) }
 
     scope :with_snippets, ->(**options) do
-      select("talks.*")
-        .select_snippet("title", 0, **options)
-        .select_snippet("summary", 1, **options)
-        .select_snippet("speaker_names", 2, **options)
+      select("talks.*").merge(Talk::Index.snippets(**options))
     end
 
     scope :ranked, -> do
       select("talks.*,
           bm25(talks_search_index, 10.0, 1.0, 5.0) +
           (strftime('%s', 'now') - strftime('%s', talks.date)) * #{DATE_WEIGHT} AS combined_score")
-        .order(Arel.sql("combined_score ASC"))
+        .order(combined_score: :asc)
     end
 
-    after_create_commit :create_in_index
-    after_update_commit :update_in_index
-    after_destroy_commit :remove_from_index
+    after_save_commit :reindex
   end
 
   class_methods do
-    def rebuild_search_index
-      connection.execute("DELETE FROM talks_search_index")
-      Talk.find_each(&:create_in_index)
-    end
-
-    def select_snippet(column, offset, tag: "mark", omission: "…", limit: 32)
-      select("snippet(talks_search_index, #{offset}, '<#{tag}>', '</#{tag}>', '#{omission}', #{limit}) AS #{column}_snippet")
+    def reindex_all
+      includes(:index).find_each(&:reindex)
     end
   end
 
   def title_with_snippet
     try(:title_snippet) || title
   end
 
-  def create_in_index
-    execute_sql_with_binds "insert into talks_search_index(rowid, title, summary, speaker_names) values (?, ?, ?, ?)", id, title, summary, speaker_names
-  end
-
-  def update_in_index
-    execute_sql_with_binds "update talks_search_index set title = ?, summary = ?, speaker_names = ? where rowid = ?", title, summary, speaker_names, id
-  end
-
-  def remove_from_index
-    execute_sql_with_binds "delete from talks_search_index where rowid = ?", id
-  end
-
-  private
-
-  def execute_sql_with_binds(*statement)
-    self.class.connection.execute self.class.sanitize_sql(statement)
+  def index
+    super || build_index
   end
+  delegate :reindex, to: :index
 end

config/initializers/inflections.rb

@@ -13,4 +13,5 @@
 # These inflection rules are supported but not enabled by default:
 ActiveSupport::Inflector.inflections(:en) do |inflect|
   inflect.acronym "GitHub"
+  inflect.acronym "SQLite"
 end

db/migrate/20241019135118_create_talk_fts.rb

@@ -5,7 +5,7 @@ def up
       "tokenize = porter"
     ]
 
-    Talk.rebuild_search_index
+    Talk.reindex_all
   end
 
   def down

test/models/talk_test.rb

@@ -204,6 +204,24 @@ class TalkTest < ActiveSupport::TestCase
     assert_equal [@talk], Talk.ft_search("Hotwire Cookbook")
     assert_equal [@talk], Talk.ft_search("Hotwire Cookbook: Common Uses, Essential Patterns")
     assert_equal [@talk], Talk.ft_search('Hotwire"') # with an escaped quote
+
+    @talk.index.destroy!
+    @talk.reload.reindex # Need to reload or we get a FrozenError from trying to update attributes on the destroyed index record.
+    assert_equal [@talk], Talk.ft_search("Hotwire Cookbook")
+  end
+
+  test "full text search creating and deleting a talk" do
+    talk = Talk.create!(title: "Full text seach with Sqlite", summary: "On using sqlite full text search with an ActiveRecord backed virtual table")
+    talk.speakers.create!(name: "Kasper Timm Hansen")
+
+    assert_equal [talk], Talk.ft_search("sqlite full text search") # title
+    assert_equal [talk], Talk.ft_search("ActiveRecord backed virtual table") # summary
+    assert_equal [talk], Talk.ft_search("Kasper Timm Hansen") # speaker
+
+    talk.destroy
+    assert_empty Talk.ft_search("sqlite full text search")
+    assert_empty Talk.ft_search("ActiveRecord backed virtual table")
+    assert_empty Talk.ft_search("Kasper Timm Hansen")
   end
 
   test "full text search on title with snippets" do

test/test_helper.rb

@@ -22,7 +22,7 @@ class ActiveSupport::TestCase
     #   true
     # end
 
-    Talk.rebuild_search_index
+    Talk.reindex_all
     Speaker.rebuild_search_index
   end
   # Run tests in parallel with specified workers