Use default value for field is array and value is nil

Fix: #80

lib/active_record/typed_store/field.rb

@@ -11,12 +11,12 @@ def initialize(name, type, options={})
 
       @accessor = options.fetch(:accessor, true)
       @name = name
+      @array = options.fetch(:array, false)
       if options.key?(:default)
         @default = extract_default(options[:default])
       end
       @null = options.fetch(:null, true)
       @blank = options.fetch(:blank, true)
-      @array = options.fetch(:array, false)
     end
 
     def has_default?
@@ -27,6 +27,8 @@ def cast(value)
       casted_value = type_cast(value)
       if !blank
         casted_value = default if casted_value.blank?
+      elsif array && has_default?
+        casted_value = default if value.nil?
       elsif !null
         casted_value = default if casted_value.nil?
       end

spec/active_record/typed_store_spec.rb

@@ -524,7 +524,7 @@
   describe 'model.typed_stores' do
     it "can access keys" do
       stores = model.class.typed_stores
-      expect(stores[:settings].keys).to eq [:no_default, :name, :email, :cell_phone, :public, :enabled, :age, :max_length, :rate, :price, :published_on, :remind_on, :published_at_time, :remind_at_time, :published_at, :remind_at, :total_price, :shipping_cost, :grades, :tags, :nickname, :author, :source, :signup, :country]
+      expect(stores[:settings].keys).to eq [:no_default, :name, :email, :cell_phone, :public, :enabled, :age, :max_length, :rate, :price, :published_on, :remind_on, :published_at_time, :remind_at_time, :published_at, :remind_at, :total_price, :shipping_cost, :grades, :tags, :subjects, :nickname, :author, :source, :signup, :country]
     end
 
     it "can access keys even when accessors are not defined" do
@@ -889,9 +889,15 @@
       expect(model.reload.grades).to be == [[1, 2], [3, 4, 5]]
     end
 
+    it 'defaults to [] if provided default is not an array' do
+      model.update(subjects: nil)
+      expect(model.reload.subjects).to be == []
+    end
+
+    # Not sure about pg_native and if this test should be outside of this block.
     it 'retreive default if assigned null' do
       model.update(tags: nil)
-      expect(model.reload.tags).to be == []
+      expect(model.reload.tags).to be == ['article']
     end
   end
 end

spec/support/models.rb

@@ -43,7 +43,8 @@ def define_columns(t, array: false)
 
   if t.is_a?(ActiveRecord::TypedStore::DSL)
     t.integer :grades, array: true
-    t.string :tags, array: true, null: false, default: [].to_yaml
+    t.string :tags, array: true, null: false, default: ['article']
+    t.string :subjects, array: true, null: false, default: ['mathematics'].to_yaml
 
     t.string :nickname, blank: false, default: 'Please enter your nickname'
   end