Fix to_hash called on errors raises an error

Author: skryukov

lib/inertia_rails/controller.rb

@@ -157,7 +157,14 @@ def inertia_location(url)
 
     def capture_inertia_errors(options)
       if (inertia_errors = options.dig(:inertia, :errors))
-        session[:inertia_errors] = inertia_errors.to_hash
+        if inertia_errors.respond_to?(:to_hash)
+          session[:inertia_errors] = inertia_errors.to_hash
+        else
+          InertiaRails.deprecator.warn(
+            "Object passed to `inertia: { errors: ... }` must respond to `to_hash`. Pass a hash-like object instead."
+          )
+          session[:inertia_errors] = inertia_errors
+        end
       end
     end
   end

spec/dummy/app/controllers/inertia_test_controller.rb

@@ -47,6 +47,10 @@ def redirect_with_inertia_errors
     redirect_to empty_test_path, inertia: { errors: { uh: 'oh' } }
   end
 
+  def redirect_with_non_hash_inertia_errors
+    redirect_to empty_test_path, inertia: { errors: 'uh oh' }
+  end
+
   def redirect_with_inertia_error_object
     redirect_to empty_test_path, inertia: { errors: MyError.new }
   end

spec/dummy/config/routes.rb

@@ -24,6 +24,7 @@
   get 'redirect_with_inertia_errors' => 'inertia_test#redirect_with_inertia_errors'
   post 'redirect_with_inertia_errors' => 'inertia_test#redirect_with_inertia_errors'
   post 'redirect_with_inertia_error_object' => 'inertia_test#redirect_with_inertia_error_object'
+  post 'redirect_with_non_hash_inertia_errors' => 'inertia_test#redirect_with_non_hash_inertia_errors'
   post 'redirect_back_with_inertia_errors' => 'inertia_test#redirect_back_with_inertia_errors'
   post 'redirect_back_or_to_with_inertia_errors' => 'inertia_test#redirect_back_or_to_with_inertia_errors'
   get 'error_404' => 'inertia_test#error_404'

spec/inertia/error_sharing_spec.rb

@@ -17,6 +17,18 @@
       expect(session[:inertia_errors]).not_to be
     end
 
+    it 'accepts a non-hash error object' do
+      expect { post redirect_with_non_hash_inertia_errors_path, headers: headers }
+        .to output(/Object passed to `inertia: { errors: ... }` must respond to `to_hash`/).to_stderr
+      expect(response.headers['Location']).to eq(empty_test_url)
+      expect(session[:inertia_errors]).to eq('uh oh')
+
+      # Follow the redirect
+      get response.headers['Location'], headers: headers
+      expect(response.body).to include({ errors: 'uh oh' }.to_json)
+      expect(session[:inertia_errors]).not_to be
+    end
+
     it 'keeps errors around when the post has a stale version' do
       post redirect_with_inertia_errors_path, headers: headers
       expect(response.headers['Location']).to eq(empty_test_url)