Add a way to reach specific training modules and slides via ID numbers

app/controllers/training_controller.rb

@@ -59,6 +59,15 @@ def reload
     render plain: e.message
   end
 
+  def find_slide
+    training_slide = TrainingSlide.find(params[:slide_id])
+    training_module = training_slide.find_module_by_slug
+    raise ActionController::RoutingError, 'module not found' unless training_module
+    # Use a specific training library for the module, or a default library if it is not found
+    training_library = training_module.find_or_default_library
+    redirect_to "/training/#{training_library.slug}/#{training_module.slug}/#{training_slide.slug}"
+  end
+
   private
 
   def add_training_root_breadcrumb

app/controllers/training_modules_controller.rb

@@ -11,4 +11,11 @@ def index
   def show
     @training_module = TrainingModule.find_by(slug: params[:module_id])
   end
+
+  def find
+    training_module = TrainingModule.find(params[:module_id])
+    # Use a specific training library for the module, or a default library if it is not found
+    training_library = training_module.find_or_default_library
+    redirect_to "/training/#{training_library.slug}/#{training_module.slug}"
+  end
 end

app/models/training_library.rb

@@ -97,4 +97,10 @@ def translated_categories
   def translated(key)
     translations.dig(I18n.locale.to_s, key)
   end
+
+  def training_module_slugs
+    categories.map do |cat|
+      cat['modules'].map { |mod| mod['slug'] }
+    end.flatten
+  end
 end

app/models/training_module.rb

@@ -153,5 +153,17 @@ def sandbox_location
     settings['sandbox_location']
   end
 
+  # Returns the first library that has a category including the module slug.
+  # It returns nil if no such library is found.
+  def find_library_by_slug
+    TrainingLibrary.all.detect { |tl| tl.training_module_slugs.include? slug }
+  end
+
+  # Returns a specific training library for the module,
+  # or a default library if it is not found.
+  def find_or_default_library
+    find_library_by_slug || TrainingLibrary.first
+  end
+
   class ModuleNotFound < StandardError; end
 end

app/models/training_slide.rb

@@ -65,4 +65,10 @@ def self.inflate(all_content, slug, wiki_page = nil)
     puts "There's a problem with file '#{slug}'"
     raise e
   end
+
+  # Returns the first module including the slide slug.
+  # It returns nil if no such module is found.
+  def find_module_by_slug
+    TrainingModule.all.detect { |tm| tm.slide_slugs.include? slug }
+  end
 end

config/routes.rb

@@ -328,6 +328,11 @@
   get 'training_modules' => 'training_modules#index'
   get 'training_module' => 'training_modules#show'
 
+  # To find training modules by id
+  get 'find_training_module/:module_id' => 'training_modules#find'
+
+  # To find individual slides by id
+  get 'find_training_slide/:slide_id' => 'training#find_slide'
 
   # Misc
   # get 'courses' => 'courses#index'

spec/controllers/training_controller_spec.rb

@@ -140,4 +140,73 @@
       end
     end
   end
+
+  describe '#find' do
+    subject { get "/find_training_module/#{module_id}" }
+
+    context 'module_id is found' do
+      let(:module_id) { 12 }
+
+      it 'redirects to a training module page' do
+        subject
+        expect(response).to redirect_to('/training/students/peer-review')
+      end
+    end
+
+    context 'module_id is found but it is in no library' do
+      let(:module_id) { 2 }
+
+      it 'uses a default library to build the route' do
+        subject
+        expect(response).to redirect_to('/training/instructors/editing-basics')
+      end
+    end
+
+    context 'module_id is not found' do
+      let(:module_id) { 128456 }
+
+      it 'raises a module not found error' do
+        expect { subject }.to raise_error ActiveRecord::RecordNotFound
+      end
+    end
+  end
+
+  describe '#find_slide' do
+    subject { get "/find_training_slide/#{slide_id}" }
+
+    context 'slide_id is found' do
+      let(:slide_id) { 103 }
+
+      it 'redirects to a training slide page' do
+        subject
+        expect(response).to redirect_to('/training/students/wikipedia-essentials/five-pillars')
+      end
+    end
+
+    context 'slide_id is found but it is in no module' do
+      let(:slide) { create(:training_slide) }
+      let(:slide_id) { slide.id }
+
+      it 'raises a routing error' do
+        expect { subject }.to raise_error ActionController::RoutingError, 'module not found'
+      end
+    end
+
+    context 'slide_id is found but its module is in no library' do
+      let(:slide_id) { 201 }
+
+      it 'uses a default library to build the route' do
+        subject
+        expect(response).to redirect_to('/training/instructors/editing-basics/welcome-students')
+      end
+    end
+
+    context 'slide_id is not found' do
+      let(:slide_id) { 128456 }
+
+      it 'raises a module not found error' do
+        expect { subject }.to raise_error ActiveRecord::RecordNotFound
+      end
+    end
+  end
 end

spec/factories/training_slides.rb

@@ -19,5 +19,8 @@
 
 FactoryBot.define do
   factory :training_slide do
+    id { 456875 }
+    title { 'How to create a slide' }
+    slug { 'how-to-create-a-slide' }
   end
 end