ruby - Rails not including timestamps even though I specifically ask for them -

i having problem ror. need fields created_at , updated_at in in tables further use. rails doesn't seem add them though ask rails to. these models:

picture.rb class picture < activerecord::base     belongs_to :category     has_many :comments, dependent: :destroy     mount_uploader :photo, photouploader     validates_presence_of :photo end      category.rb     class category < activerecord::base     has_many :pictures, dependent: :destroy     validates :name, presence: true, uniqueness: { case_sensitive: false } end      comment.rb class comment < activerecord::base   belongs_to :user   belongs_to :picture    validates :text, presence: true end 

these migrations:

class createcategories < activerecord::migration   def change     create_table :categories |t|       t.string :name       t.timestamps     end   end end  class createpictures < activerecord::migration   def change     create_table :pictures |t|       t.string :description       t.references :category, index: true       t.timestamps     end     add_foreign_key :pictures, :categories   end end  class addphototopictures < activerecord::migration   def change     add_column :pictures, :photo, :string   end end   class createcomments < activerecord::migration   def change     create_table :comments |t|       t.string :text       t.references :user, index: true       t.references :picture, index: true        t.timestamps     end     add_foreign_key :comments, :users     add_foreign_key :comments, :pictures   end end  class addtimestampstopicture < activerecord::migration   def change_table     change_table :pictures |t|     t.timestamps     end end   

as can see trying add 2 columns. when try seeing created_at field "undefined method created_at'" . checking in rails c see if fields there no, fields not exist. using pg gem . using carrierwave gem upload pictures. why rails not include these 2 columns ? here link project itself.
coorasse suggested took @ schema.

create_table "pictures", force: :cascade |t|     t.string   "description"     t.integer  "category_id"     t.string   "photo_file_name"     t.string   "photo_content_type"     t.integer  "photo_file_size"     t.datetime "photo_updated_at"     t.string   "photo"   end   

it seems didn't update herself. why?

to force shema updated drop db , recreate it.

but aware - erase whole database.

rake db:drop && rake db:create && rake db:migrate 

you can't edit schema or migration files. if adding new columns - should through new migration.

but if taking editing migrations files road you'll have (problems) drop db , recreate it.