FIX: Correctly handle the print param on topics#show. (#16555)

The controller incorrectly sets print to true when passing `print=false`, which causes the rate limit to perform.

app/controllers/topics_controller.rb

@@ -66,7 +66,7 @@ class TopicsController < ApplicationController
     opts = params.slice(:username_filters, :filter, :page, :post_number, :show_deleted, :replies_to_post_number, :filter_upwards_post_id, :filter_top_level_replies)
     username_filters = opts[:username_filters]
 
-    opts[:print] = true if params[:print].present?
+    opts[:print] = true if params[:print] == 'true'
     opts[:username_filters] = username_filters.split(',') if username_filters.is_a?(String)
 
     # Special case: a slug with a number in front should look by slug first before looking

config/routes.rb

@@ -823,7 +823,7 @@ Discourse::Application.routes.draw do
     # Topic routes
     get "t/id_for/:slug" => "topics#id_for_slug"
     get "t/external_id/:external_id" => "topics#show_by_external_id", format: :json, constrains: { external_id: /\A[\w-]+\z/ }
-    get "t/:slug/:topic_id/print" => "topics#show", format: :html, print: true, constraints: { topic_id: /\d+/ }
+    get "t/:slug/:topic_id/print" => "topics#show", format: :html, print: 'true', constraints: { topic_id: /\d+/ }
     get "t/:slug/:topic_id/wordpress" => "topics#wordpress", constraints: { topic_id: /\d+/ }
     get "t/:topic_id/wordpress" => "topics#wordpress", constraints: { topic_id: /\d+/ }
     get "t/:slug/:topic_id/moderator-liked" => "topics#moderator_liked", constraints: { topic_id: /\d+/ }

spec/requests/topics_controller_spec.rb

@@ -2002,6 +2002,13 @@ RSpec.describe TopicsController do
       expect(response.status).to eq(404)
     end
 
+    it "doesn't use print mode when print equals false" do
+      SiteSetting.max_prints_per_hour_per_user = 0
+
+      get "/t/#{topic.slug}/#{topic.id}.json?print=false"
+      expect(response.status).to eq(200)
+    end
+
     context 'a topic with nil slug exists' do
       before do
         nil_slug_topic = Fabricate(:topic)