Merge pull request #209 from Andy9822/add-helper-for-inertia-rendering

Add `inertia_rendering?` method and set instance variable in renderer

Author: bknoles

lib/inertia_rails/helper.rb

@@ -11,4 +11,8 @@ def inertia_headers
     )
     inertia_ssr_head
   end
+
+  def inertia_rendering?
+    controller.instance_variable_get("@_inertia_rendering")
+  end
 end

lib/inertia_rails/renderer.rb

@@ -34,6 +34,7 @@ def initialize(component, controller, request, response, render_method, props: n
       @deep_merge = deep_merge.nil? ? configuration.deep_merge_shared_data : deep_merge
       @encrypt_history = encrypt_history.nil? ? configuration.encrypt_history : encrypt_history
       @clear_history = clear_history || controller.session[:inertia_clear_history] || false
+      @controller.instance_variable_set('@_inertia_rendering', true)
     end
 
     def render

spec/inertia/helper_spec.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+RSpec.describe InertiaRails::Helper do
+  let(:controller) { ApplicationController.new }
+
+  let(:test_helper) do
+    Class.new do
+      include InertiaRails::Helper
+      attr_accessor :controller
+    end.new
+  end
+
+  before do
+    test_helper.controller = controller
+  end
+
+  describe '#inertia_rendering?' do
+    context 'when not rendering through Inertia' do
+      it 'returns nil' do
+        expect(test_helper.inertia_rendering?).to be_nil
+      end
+    end
+
+    context 'when rendering through Inertia' do
+      before do
+        controller.instance_variable_set('@_inertia_rendering', true)
+      end
+
+      it 'returns true' do
+        expect(test_helper.inertia_rendering?).to be true
+      end
+    end
+  end
+end