rails 4 rake 中止！在heroku上

Question

rake db:migrate 在开发中运行良好，应用程序也是如此。只有使用 heroku 我才会遇到麻烦

$ heroku run rake db:migrate

Running `rake db:migrate` attached to terminal... up, run.5905
-- create_table(:users)
-- create_table(:users)
rake aborted!
ActiveRecord::MigrationProxy#disable_ddl_transaction delegated to 
migration.disable_ddl_transaction, but migration is nil: 
#<struct ActiveRecord::MigrationProxy name="DeviseCreateAdmins", 
version=20130802210826, filename="/app/db/migrate/20130802210826_devise_create_admins.rb", 
scope=""

迁移文件：

class DeviseCreateAdmins < ActiveRecord::Migration
  create_table :users do |t|
    t.database_authenticatable
    t.confirmable
    t.recoverable
    t.rememberable
    t.trackable
    t.timestamps
  end
end

有人对迁移失败的原因有任何想法吗？

Answer 1

您缺少方法名称，

class DeviseCreateAdmins < ActiveRecord::Migration
  def change
    create_table :users do |t|
      t.database_authenticatable
      t.confirmable
      t.recoverable
      t.rememberable
      t.trackable
      t.timestamps
    end
  end
end

注意开头的def change。