PG :: UndefinedColumn：错误：关系“文章”的列“image_file_name”不存在

Question

有人可以帮我运行heroku run db:migrate吗？我忘了在 heroku 上运行 db:migration 以及在 dev env 上运行迁移。我做了几个，现在我收到以下错误：

wozane:~/workspace (master) $ heroku run rake db:migrate                           
Running rake db:migrate on ⬢ wozane... up, run.7786
   (0.8ms)  SELECT pg_try_advisory_lock(96974639112725850);
  ActiveRecord::SchemaMigration Load (1.1ms)  SELECT "schema_migrations".* FROM "schema_migrations"
Migrating to RemoveColumnImage (20160917131520)
   (0.7ms)  BEGIN
== 20160917131520 RemoveColumnImage: migrating ================================
-- remove_column(:articles, :image_file_name, :string)
   (1.5ms)  ALTER TABLE "articles" DROP "image_file_name"
   (0.7ms)  ROLLBACK
   (0.8ms)  SELECT pg_advisory_unlock(96974639112725850)
rake aborted!
StandardError: An error has occurred, this and all later migrations canceled:

PG::UndefinedColumn: ERROR:  column "image_file_name" of relation "articles" does not exist
: ALTER TABLE "articles" DROP "image_file_name"

情况是该列已被删除，不存在。

错误消息中提到的迁移（编号 20160917131520）：

class RemoveColumnImage < ActiveRecord::Migration[5.0]
  def change
    remove_column :articles, :image_file_name , :string
    remove_column :articles, :image_content_type, :string
    remove_column :articles, :image_file_size, :integer
    remove_column :articles, :image_updated_at, :datetime
  end
end

Schema.rb 看起来像这样：

ActiveRecord::Schema.define(version: 20160921115118) do

  create_table "articles", force: :cascade do |t|
    t.string   "title"
    t.text     "text"
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.string   "img_url"
  end

  create_table "photos", force: :cascade do |t|
    t.datetime "created_at", null: false
    t.datetime "updated_at", null: false
    t.string   "title"
    t.string   "img_url"
    t.text     "text"
  end

end

我尝试#迁移中的整个代码，但它对那些不起作用的 cmets 没有帮助：

rails db:environment:set RAILS_ENV=production
heroku run rake db:reset 
heroku run rake db:migrate -app wozane
heroku pg:reset DATABASE --confirm wozane

有人知道如何在我的情况下运行 heroku 迁移吗？

提前致谢。

Answer 1

只需注释掉删除列迁移的代码。

class RemoveColumnImage < ActiveRecord::Migration[5.0]
  def change
    #remove_column :articles, :image_file_name , :string
    #remove_column :articles, :image_content_type, :string
    #remove_column :articles, :image_file_size, :integer
    #remove_column :articles, :image_updated_at, :datetime
  end
end

并尝试运行 heroku run rake db:migrate -app wozane