Adding Sequel adapter to Trestle Admin

adding-sequel-adapter.diff

Index: lib/trestle/adapters.rb
     autoload :ActiveRecordAdapter
     autoload :DraperAdapter
+    autoload :SequelAdapter
 
     class Adapter
       attr_reader :admin

Index: lib/trestle/attribute.rb
     end
 
     def primary_key?
-      name.to_s == admin.model.primary_key
+      name.to_s == admin.model.primary_key.to_s
     end
 
     def inheritance_column?
-      name.to_s == admin.model.inheritance_column
+      name.to_s == admin.model.try(:inheritance_column)
     end
 
     def counter_cache?
Index: lib/trestle/configuration.rb
     option :persistent_params, [:sort, :order, :scope]
 
-    option :default_adapter, Adapters::Adapter.compose(Adapters::ActiveRecordAdapter, Adapters::DraperAdapter)
+    option :default_adapter, Adapters::Adapter.compose(Adapters::ActiveRecordAdapter, Adapters::DraperAdapter, Adapters::SequelAdapter)
 
     option :root_breadcrumbs, -> { [Trestle::Breadcrumb.new(I18n.t("admin.breadcrumbs.home", default: "Home"), Trestle.config.path)] }
 
Index: lib/trestle/form/field.rb
       end
 
       def errors
-        errors = builder.object.errors[name]
-        errors += builder.object.errors[name.to_s.sub(/_id$/, '')] if name.to_s =~ /_id$/
+        errors = builder.object.errors[name].to_a
+        errors += builder.object.errors[name.to_s.sub(/_id$/, '')].to_a if name.to_s =~ /_id$/
         errors
       end
 
Index: lib/trestle/adapters/sequel_adapter.rb
+Sequel::Model.plugin :active_model
+
+module Trestle
+  module Adapters
+    module SequelAdapter
+      def collection(params={})
+        admin.model.dataset
+      end
+
+      def find_instance(params)
+        admin.model[params[:id]]
+      end
+
+      def build_instance(params={})
+        admin.model.new(params)
+      end
+
+      def update_instance(instance, params)
+        instance.set(params)
+      end
+
+      def save_instance(instance)
+        instance.save
+      end
+
+      def delete_instance(instance)
+        instance.destroy
+      end
+
+      def to_param(instance)
+        instance
+      end
+
+      def unscope(scope)
+        scope.unfiltered
+      end
+
+      def merge_scopes(scope, other)
+        scope.where(id: other.select(:id))
+      end
+
+      def sort(collection, field, order)
+        collection.order(Sequel.send(order, field))
+      end
+
+      def paginate(collection, params)
+        collection = Kaminari.paginate_array(collection.to_a) unless collection.respond_to?(:page)
+        collection.page(params[:page])
+      end
+
+      def count(collection)
+        collection.count
+      end
+
+      def default_attributes
+        reflections = admin.model.association_reflections
+        admin.model.db_schema.map do |column_name, column_attrs|
+          if reflection = reflections[column_name]
+            Attribute::Association.new(admin, column_name, reflection.class.safe_constantize)
+          else
+            Attribute.new(admin, column_name, column_attrs[:type])
+          end
+        end
+      end
+    end
+  end
+end