Question

我已将Rails 2.3.14项目转换为Rails 3.2.2 对于不直接从ActiveRecord::Base

下降的表格，我遇到了问题

我的模型定义如下：

class PauaServiceTable < ActiveRecord::Base
    def self.abstract_class?
       true
    end
    ..
    ..
 end

我有很多类来自这个类。例如：

 class Lookup < PauaServiceTable
    ...
 end

在Rails console (3.3.2)中，我可以实例化直接从Activerecord::Base下降的任何表，但是从PauaServiceTable继承的任何表都会失败并显示以下堆栈跟踪：

Loading development environment (Rails 3.2.2)
ruby-1.8.7-p334 :001 > l=Lookup.new
ActiveRecord::StatementInvalid: Mysql2::Error: Incorrect table name '': SHOW FULL FIELDS FROM ``
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:243:in `query'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:243:in `execute'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/connection_adapters/abstract_adapter.rb:280:in `log'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activesupport-3.2.2/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/connection_adapters/abstract_adapter.rb:275:in `log'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:243:in `execute'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/connection_adapters/mysql2_adapter.rb:211:in `execute'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:257:in `execute_and_free'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/connection_adapters/abstract_mysql_adapter.rb:424:in `columns'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/connection_adapters/schema_cache.rb:12:in `initialize'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/model_schema.rb:228:in `call'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/model_schema.rb:228:in `default'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/model_schema.rb:228:in `[]'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/model_schema.rb:228:in `columns'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/model_schema.rb:243:in `column_defaults'
    from /Users/george/.rvm/gems/ruby-1.8.7-p334@rails322/gems/activerecord-3.2.2/lib/active_record/base.rb:479:in `initialize'
    from (irb):1:in `new'
    from (irb):1ruby-1.8.7-p334 :002 >

此代码在Rails 2.3.14中运行良好，但现在在转换为3.2.2后失败。

Answer 1

尝试在@abstract_class = true

中设置class PauaServiceTable

---已编辑

由于某种原因，table_name为空，请尝试以下操作：

class Lookup < PauaServiceTable
  set_table_name 'lookups'
end

我可以使用以下代码重现您的错误：

class PauaServiceTable < ActiveRecord::Base
  def self.abstract_class?
    true
  end
end

class Lookup < PauaServiceTable
end

但是，以下工作：

class PauaServiceTable < ActiveRecord::Base
  @abstract_class = true
end

class Lookup < PauaServiceTable
end


l= Lookup.new
+----+------------+------------+
| id | created_at | updated_at |
+----+------------+------------+
|    |            |            |
+----+------------+------------+

Answer 2

单个表格的PauaServiceTable和Lookup模型是什么？

如果是这样，那么您的PauaServiceTable模型应该具有表名，Lookup表应该自动获取它。您还可以查看Single Table Inheritance。

如果没有，意味着两个模型用于两个表，为什么Lookup应该继承PauaServiceTable？您可能需要在这两个has_many之间建立关系（has_one，model等）。

Answer 3

对于Rails 3.2.1+，我相信你想要

class PauaServiceTable < ActiveRecord::Base
  self.abstract_class = true
end

请参阅ActiveRecord::Inheritance::ClassMethods

无法直接从ActiveRecord :: Base下载的访问模型

3 个答案: