Adding an error message during 'administrate' initialize when there are no models in db.

lib/generators/administrate/install/install_generator.rb

@@ -1,3 +1,9 @@
+if defined?(Zeitwerk)
+  Zeitwerk::Loader.eager_load_all
+else
+  Rails.application.eager_load!
+end
+
 require "rails/generators/base"
 require "administrate/generator_helpers"
 require "administrate/namespace"
@@ -31,6 +37,12 @@ def run_dashboard_generators
         end
       end
 
+      def model_check
+        if valid_dashboard_models.none?
+          puts "WARNING: Add models before installing Administrate."
+        end
+      end
+
       private
 
       def namespace
@@ -44,6 +56,30 @@ def singular_dashboard_resources
       def dashboard_resources
         Administrate::Namespace.new(namespace).resources
       end
+
+      def valid_dashboard_models
+        database_models - invalid_dashboard_models
+      end
+
+      def database_models
+        ActiveRecord::Base.descendants.reject(&:abstract_class?)
+      end
+
+      def invalid_dashboard_models
+        (models_without_tables + namespaced_models + unnamed_constants).uniq
+      end
+
+      def models_without_tables
+        database_models.reject(&:table_exists?)
+      end
+
+      def namespaced_models
+        database_models.select { |model| model.to_s.include?("::") }
+      end
+
+      def unnamed_constants
+        ActiveRecord::Base.descendants.reject { |d| d.name == d.to_s }
+      end
     end
   end
 end