add meilisearch

this thing is way too fast!  only downside is that indexing takes a bit
longer, and the search indexes are big (16Gi for 2.7 million records)

i have no idea how to properly integrate it in the UI, but it seems
promising :^)

Gemfile

@@ -119,3 +119,4 @@ gem "mail", "~> 2.7.1"
 
 gem "prometheus-client", "~> 4.2"
 
+gem "meilisearch-rails", "~> 0.10.1"

Gemfile.lock

@@ -249,6 +249,10 @@ GEM
     mail (2.7.1)
       mini_mime (>= 0.1.1)
     marcel (1.0.2)
+    meilisearch (0.25.1)
+      httparty (>= 0.17.1, < 0.22.0)
+    meilisearch-rails (0.10.1)
+      meilisearch (~> 0.25.0)
     method_source (1.0.0)
     mime-types (3.5.1)
       mime-types-data (~> 3.2015)
@@ -535,6 +539,7 @@ DEPENDENCIES
   letter_opener
   lograge
   mail (~> 2.7.1)
+  meilisearch-rails (~> 0.10.1)
   mini_magick
   net-imap
   net-pop

Procfile.dev

@@ -2,3 +2,4 @@ web: unset PORT && bin/rails server
 worker: bundle exec sidekiq
 css: yarn build:css --watch
 js: yarn build --watch
+search: meilisearch --no-analytics --env development --db-path tmp/meilisearch/db --dump-dir tmp/meilisearch/dump --master-key justfordev42069e621

app/controllers/search_controller.rb

@@ -1,9 +1,35 @@
 class SearchController < ApplicationController
   def index
     @results = []
-    query = params[:q]
-    return if query.blank?
+    @query = params[:q]
+    return if @query.blank?
 
-    @results = []
+    @results = if params[:multi_search] == "1"
+                 multi_search_experiment
+               else
+                 [*Answer.search(@query), *Question.search(@query)]
+               end
+  end
+
+  private
+
+  def multi_search_experiment
+    MeiliSearch::Rails.client.multi_search(
+      [Answer, Question].map do |klass|
+        {
+          q:                  @query,
+          index_uid:          klass.name.to_s,
+          show_ranking_score: true,
+        }
+      end
+    )["results"].flat_map do |h|
+      model = h["indexUid"].constantize # bad practice!
+      results = model.find(h["hits"].pluck("id")).map { |r| [r.id.to_s, r] }.to_h
+      h["hits"].map { |hit| [hit["_rankingScore"], results[hit["id"]]] }
+    end
+      .sort_by(&:first)
+      .reverse
+      .tap { |results| Rails.logger.debug(results) }
+      .map(&:last)
   end
 end

app/models/answer.rb

@@ -1,6 +1,12 @@
 class Answer < ApplicationRecord
   extend Answer::TimelineMethods
 
+  include MeiliSearch::Rails
+
+  meilisearch do
+    attribute :content
+  end
+
   belongs_to :user, counter_cache: :answered_count
   belongs_to :question, counter_cache: :answer_count
   has_many :comments, dependent: :destroy

app/models/question.rb

@@ -1,6 +1,12 @@
 class Question < ApplicationRecord
   include Question::AnswerMethods
 
+  include MeiliSearch::Rails
+
+  meilisearch do
+    attribute :content
+  end
+
   belongs_to :user, optional: true
   has_many :answers, dependent: :destroy
   has_many :inboxes, dependent: :destroy

app/views/search/index.haml

@@ -3,18 +3,19 @@
     .col-sm-10.col-md-10.col-lg-9.mx-auto
       .card
         .card-body
-          = bootstrap_form_tag layout: :inline, method: :get do |f|
-            = f.text_field :q, skip_label: true, append: f.primary("Search")
+          = bootstrap_form_with url: search_path, layout: :inline, method: :get do |f|
+            = f.text_field :q, skip_label: true, append: f.primary("Search"), value: params[:q]
+            = f.check_box :multi_search, label: "Multisearch"
   - unless @results.blank?
     .container-lg.container--main
       .row
         .col-sm-10.col-md-10.col-lg-9.mx-auto
           - @results.each do |result|
-            - case result.searchable
+            - case result
               - when Answer
-                = render "answerbox", a: result.searchable, display_all: false, subscribed_answer_ids: []
+                = render "answerbox", a: result, display_all: false, subscribed_answer_ids: []
               - when Question
-                = render "shared/question", q: result.searchable, type: nil
+                = render "shared/question", q: result, type: nil
 
 = render 'shared/links'
 

config/initializers/meilisearch.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+return unless ENV["SEARCH_ENABLED"] == "true"
+
+MeiliSearch::Rails.configuration = {
+  meilisearch_url: ENV.fetch("MEILISEARCH_HOST", "http://localhost:7700"),
+  meilisearch_api_key: ENV.fetch("MEILISEARCH_API_KEY", "justfordev42069e621")
+}