add rails_best_practices/always_add_db_index snippet

Author: flyerhzm

lib/rails_best_practices/always_add_db_index.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+Synvert::Rewriter.new 'rails_best_practices', 'always_add_db_index' do
+  description <<~EOS
+  EOS
+
+  call_helper 'rails/parse'
+  rails_tables = load_data :rails_tables
+  rails_models = load_data :rails_models
+
+  configure(parser: Synvert::PRISM_PARSER)
+
+  helper_method :foreign_key_column do |association|
+    association[:foreign_key]&.to_s || association[:name].foreign_key
+  end
+
+  helper_method :foreign_type_column do |association|
+    association[:foreign_type]&.to_s || (association[:name].demodulize + '_type').underscore
+  end
+
+  within_files 'db/schema.rb' do
+    rails_tables.each do |table_name, table_info|
+      belongs_to_associations = rails_models[:associations].select do |association|
+        # find all belongs_to associations
+        association[:class_name].tableize == table_name || association[:type] == 'belongs_to'
+      end
+      polymorphic_belongs_to_associations = belongs_to_associations.select do |association|
+        next false unless association[:polymorphic]
+
+        # find all belongs_to associations without db index
+        table_info[:columns].find { |column| column[:name] == foreign_key_column(association) } &&
+        table_info[:columns].find { |column| column[:name] == foreign_type_column(association) } &&
+        !table_info[:indices].find { |index| index[:columns].first == foreign_type_column(association) && index[:columns].second == foreign_key_column(association) }
+      end
+      general_belongs_to_associations = belongs_to_associations.select do |association|
+        !association[:polymorphic] &&
+        # find all belongs_to associations without db index
+        table_info[:columns].find { |column| column[:name] == foreign_key_column(association) } &&
+        !table_info[:indices].find { |index| index[:columns].first == foreign_key_column(association) }
+      end
+
+      polymorphic_belongs_to_associations.each do |association|
+        find_node ".call_node[receiver=nil][name=create_table][arguments!=nil][arguments.arguments.first='#{table_name}']
+                   .call_node[receiver=t][arguments!=nil][arguments.arguments.first='#{association[:name].foreign_key}']" do
+          warn "always add db index #{table_name} => [\"#{foreign_type_column(association)}\", \"#{foreign_key_column(association)}\"]"
+        end
+      end
+
+      general_belongs_to_associations.each do |association|
+        find_node ".call_node[receiver=nil][name=create_table][arguments!=nil][arguments.arguments.first='#{table_name}']
+                   .call_node[receiver=t][arguments!=nil][arguments.arguments.first='#{foreign_key_column(association)}']" do
+          warn "always add db index #{table_name} => [\"#{foreign_key_column(association)}\"]"
+        end
+      end
+    end
+  end
+end

spec/rails_best_practices/always_add_db_index_spec.rb

@@ -0,0 +1,133 @@
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe 'Rails always add db index' do
+  before { load_helpers(%w[helpers/parse_rails]) }
+
+  context 'index exists' do
+    let(:rewriter_name) { 'rails_best_practices/always_add_db_index' }
+    let(:file_paths) { %w[db/schema.rb app/models/comment.rb] }
+    let(:test_contents) { [<<~EOF.strip, <<~EOF.strip] }
+      ActiveRecord::Schema[7.1].define(version: 2024_04_22_081242) do
+        enable_extension "plpgsql"
+
+        create_table "comments", force: :cascade do |t|
+          t.string "content", null: false
+          t.bigint "post_id", null: false
+          t.integer "user_id", null: false
+          t.index ["post_id"], name: "index_comments_on_post_id"
+          t.index ["user_id"], name: "index_comments_on_user_id"
+        end
+      end
+    EOF
+      class Comment < ApplicationRecord
+        belongs_to :post
+        belongs_to :user
+      end
+    EOF
+    let(:warnings) { [] }
+
+    include_examples 'warnable'
+  end
+
+  context 'index is missing' do
+    let(:rewriter_name) { 'rails_best_practices/always_add_db_index' }
+    let(:file_paths) { %w[db/schema.rb app/models/comment.rb] }
+    let(:test_contents) { [<<~EOF.strip, <<~EOF.strip] }
+      ActiveRecord::Schema[7.1].define(version: 2024_04_22_081242) do
+        enable_extension "plpgsql"
+
+        create_table "comments", force: :cascade do |t|
+          t.string "content", null: false
+          t.bigint "post_id", null: false
+          t.integer "user_id", null: false
+        end
+      end
+    EOF
+      class Comment < ApplicationRecord
+        belongs_to :post
+        belongs_to :user
+      end
+    EOF
+    let(:warnings) { [
+      '/db/schema.rb#6: always add db index comments => ["post_id"]',
+      '/db/schema.rb#7: always add db index comments => ["user_id"]'
+    ] }
+
+    include_examples 'warnable'
+  end
+
+  context 'polymorphic index exists' do
+    let(:rewriter_name) { 'rails_best_practices/always_add_db_index' }
+    let(:file_paths) { %w[db/schema.rb app/models/picture.rb] }
+    let(:test_contents) { [<<~EOF.strip, <<~EOF.strip] }
+      ActiveRecord::Schema[7.1].define(version: 2024_04_22_081242) do
+        enable_extension "plpgsql"
+
+        create_table "pictures", force: :cascade do |t|
+          t.string "name", null: false
+          t.bigint "imageable_id", null: false
+          t.string "imageable_type", null: false
+          t.index ["imageable_type", "imageable_id"], name: "index_pictures_on_imageable_type_and_imageable_id"
+        end
+      end
+    EOF
+      class Picture < ApplicationRecord
+        belongs_to :imageable, polymorphic: true
+      end
+    EOF
+    let(:warnings) { [] }
+
+    include_examples 'warnable'
+  end
+
+  context 'polymorphic index is missing' do
+    let(:rewriter_name) { 'rails_best_practices/always_add_db_index' }
+    let(:file_paths) { %w[db/schema.rb app/models/picture.rb] }
+    let(:test_contents) { [<<~EOF.strip, <<~EOF.strip] }
+      ActiveRecord::Schema[7.1].define(version: 2024_04_22_081242) do
+        enable_extension "plpgsql"
+
+        create_table "pictures", force: :cascade do |t|
+          t.string "name", null: false
+          t.bigint "imageable_id", null: false
+          t.string "imageable_type", null: false
+        end
+      end
+    EOF
+      class Picture < ApplicationRecord
+        belongs_to :imageable, polymorphic: true
+      end
+    EOF
+    let(:warnings) { [
+      '/db/schema.rb#6: always add db index pictures => ["imageable_type", "imageable_id"]',
+    ] }
+
+    include_examples 'warnable'
+  end
+
+  context 'foreign_key option index is missing' do
+    let(:rewriter_name) { 'rails_best_practices/always_add_db_index' }
+    let(:file_paths) { %w[db/schema.rb app/models/comment.rb] }
+    let(:test_contents) { [<<~EOF.strip, <<~EOF.strip] }
+      ActiveRecord::Schema[7.1].define(version: 2024_04_22_081242) do
+        enable_extension "plpgsql"
+
+        create_table "comments", force: :cascade do |t|
+          t.string "content", null: false
+          t.integer "user_id", null: false
+        end
+      end
+    EOF
+      class Comment < ApplicationRecord
+        belongs_to :commentor, foreign_key: :user_id
+      end
+    EOF
+    let(:warnings) { [
+      '/db/schema.rb#6: always add db index comments => ["user_id"]'
+    ] }
+
+    include_examples 'warnable'
+  end
+end

spec/support/warnable.rb

@@ -0,0 +1,17 @@
+# frozen_string_literal: true
+
+shared_examples 'warnable' do
+  # it needs to define rewriter_name, fake_file_path (optional), test_content, warnings
+  let!(:rewriter) { load_snippet(rewriter_name) }
+
+  describe 'with fakefs', fakefs: true do
+    it 'converts' do
+      file_paths.each_with_index do |file_path, index|
+        FileUtils.mkdir_p(File.dirname(file_path))
+        File.write(file_path, test_contents[index])
+      end
+      rewriter.process
+      expect(rewriter.warnings.map(&:message)).to eq(warnings)
+    end
+  end
+end