Add call-able :scope option to Field::HasMany

lib/administrate/field/has_many.rb

@@ -97,12 +97,11 @@ def includes
       end
 
       def candidate_resources
-        if options.key?(:includes)
-          includes = options.fetch(:includes)
-          associated_class.includes(*includes).all
-        else
-          associated_class.all
-        end
+        scope = options[:scope] ? options[:scope].call(self) : associated_class.all
+        scope = scope.includes(*options.fetch(:includes)) if options.key?(:includes)
+
+        order = options.delete(:order)
+        order ? scope.reorder(order) : scope
       end
 
       def display_candidate_resource(resource)

spec/lib/fields/has_many_spec.rb

@@ -299,4 +299,56 @@
       end
     end
   end
+
+  describe "#associated_resource_options" do
+    context "with `order` option" do
+      it "returns the resources in correct order" do
+        order = create(:order)
+        create_list(:customer, 5)
+        options = {order: "name"}
+        association = Administrate::Field::HasMany.with_options(options)
+
+        field = association.new(:customer, [], :show, resource: order)
+
+        correct_order = Customer.order("name").pluck(:id)
+
+        resources = field.associated_resource_options.compact.to_h.values
+        expect(resources).to eq correct_order
+      end
+
+      it "ignores the order passed in `scope`" do
+        order = create(:order)
+        create_list(:customer, 3)
+        options = {
+          order: "name",
+          scope: ->(_field) { Customer.order(name: :desc) }
+        }
+        association = Administrate::Field::HasMany.with_options(options)
+
+        field = association.new(:customer, [], :show, resource: order)
+
+        correct_order = Customer.order("name").pluck(:id)
+
+        resources = field.associated_resource_options.compact.to_h.values
+        expect(resources).to eq correct_order
+      end
+    end
+
+    context "with `scope` option" do
+      it "returns the resources within the passed scope" do
+        # Building instead of creating, to avoid a dependent customer being
+        # created, leading to random failures
+        order = build(:order)
+
+        1.upto(3) { |i| create :customer, name: "customer-#{i}" }
+        scope = ->(_field) { Customer.order(name: :desc).limit(2) }
+
+        association = Administrate::Field::HasMany.with_options(scope: scope)
+        field = association.new(:customer, [], :show, resource: order)
+        resources = field.associated_resource_options.compact.to_h.keys
+
+        expect(resources).to eq ["customer-3", "customer-2"]
+      end
+    end
+  end
 end