From 0b61e7afeb192366b713ea7acc7093f10e8d6352 Mon Sep 17 00:00:00 2001
From: Sergio Martin <smartin@flexiant.com>
Date: Tue, 17 Nov 2015 17:51:18 +0100
Subject: [PATCH] Excludes state initialization when attribute is not included
 in the query

---
 lib/state_machines/integrations/mongoid.rb |  2 +-
 test/machine_with_limited_fields_test.rb   | 26 ++++++++++++++++++++++
 2 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 test/machine_with_limited_fields_test.rb

diff --git a/lib/state_machines/integrations/mongoid.rb b/lib/state_machines/integrations/mongoid.rb
index 07b3236..e72e783 100644
--- a/lib/state_machines/integrations/mongoid.rb
+++ b/lib/state_machines/integrations/mongoid.rb
@@ -334,7 +334,7 @@ def apply_pre_processed_defaults
               defaults = {}
               self.class.state_machines.initialize_states(self, :static => :force, :dynamic => false, :to => defaults)
               defaults.each do |attr, value|
-                send(:"\#{attr}=", value) unless attributes.include?(attr)
+                send(:"\#{attr}=", value) unless has_attribute?(attr) || attribute_missing?(attr)
               end
               super
             end
diff --git a/test/machine_with_limited_fields_test.rb b/test/machine_with_limited_fields_test.rb
new file mode 100644
index 0000000..2dc6db9
--- /dev/null
+++ b/test/machine_with_limited_fields_test.rb
@@ -0,0 +1,26 @@
+require_relative 'test_helper'
+
+class MachineWithLimitedFieldsTest < BaseTestCase
+  def setup
+    @model = new_model
+    @machine = StateMachines::Machine.new(@model, :initial => :parked)
+    @machine.state :idling
+
+    @record = @model.create
+  end
+
+  def test_should_not_set_value_when_exclude_field_in_query
+    record = @model.where(id: @record.id).only(:_id).first
+    assert_equal ["_id"], record.attributes.keys
+  end
+
+  def test_should_set_value_when_include_field_in_query
+    record = @model.where(id: @record.id).only(:_id, :state).first
+    assert_equal "parked", record.state
+  end
+
+  def test_should_fail_if_access_when_exclude_field_in_query
+    record = @model.where(id: @record.id).only(:_id).first
+    assert_raises(ActiveModel::MissingAttributeError) { record.state }
+  end
+end