我正在尝试在 Heroku 上运行 rake db:migrate 命令，但遇到了这个问题。
uninitialized constant DeviseCreateUsers
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-3.2.11/lib/active_support/inflector/methods.rb:230:in `block in constantize'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-3.2.11/lib/active_support/inflector/methods.rb:229:in `each'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-3.2.11/lib/active_support/inflector/methods.rb:229:in `constantize'
/app/vendor/bundle/ruby/2.0.0/gems/activesupport-3.2.11/lib/active_support/core_ext/string/inflections.rb:54:in `constantize'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:538:in `load_migration'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:533:in `migration'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:528:in `migrate'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:720:in `block (2 levels) in migrate'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:775:in `call'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:775:in `block in ddl_transaction'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/connection_adapters/abstract/database_statements.rb:192:in `transaction'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/transactions.rb:208:in `transaction'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:775:in `ddl_transaction'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:719:in `block in migrate'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:700:in `each'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:700:in `migrate'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:570:in `up'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/migration.rb:551:in `migrate'
/app/vendor/bundle/ruby/2.0.0/gems/activerecord-3.2.11/lib/active_record/railties/databases.rake:179:in `block (2 levels) in <top (required)>'
这是我的设计创建用户方法的全文，它似乎导致了这个问题。
class AddDeviseToCustomers < ActiveRecord::Migration
def self.up
change_table(:customers) do |t|
## Database authenticatable
t.string :email, :null => false, :default => ""
t.string :encrypted_password, :null => false, :default => ""
## Recoverable
t.string :reset_password_token
t.datetime :reset_password_sent_at
## Rememberable
t.datetime :remember_created_at
## Trackable
t.integer :sign_in_count, :default => 0
t.datetime :current_sign_in_at
t.datetime :last_sign_in_at
t.string :current_sign_in_ip
t.string :last_sign_in_ip
t.string :confirmation_token
t.datetime :confirmed_at
t.datetime :confirmation_sent_at
## Confirmable
#t.string :unconfirmed_email # Only if using reconfirmable
## Lockable
# t.integer :failed_attempts, :default => 0 # Only if lock strategy is :failed_attempts
# t.string :unlock_token # Only if unlock strategy is :email or :both
# t.datetime :locked_at
## Token authenticatable
# t.string :authentication_token
# Uncomment below if timestamps were not included in your original model.
# t.timestamps
add_index :users, :email, :unique => true
add_index :users, :reset_password_token, :unique => true
# add_index :users, :confirmation_token, :unique => true
# add_index :users, :unlock_token, :unique => true
# add_index :users, :authentication_token, :unique => true
end
end
end
这一切都在 heroku 上的 pgsql 服务器上。提前致谢