我没有使用rails,我正在尝试使用ActiveRecord来更轻松地使用现有数据库.这只是一个脚本,所以我没有
database.yml或任何其他文件.我已经使用设置了数据库连接
ActiveRecord::Base.establish_connection( adapter: 'postgresql',host: 'thehosthere',database: 'management',username: 'management_readonly',password: '',port: '5432' )
我对数据库并不熟悉,所以我只会说明我对这个数据库的了解.有很多架构.我感兴趣的模式是具有表“host”的管理模式.我在脚本中创建了一个类Host,如下所示：
class Host < ActiveRecord::Base
self.table_name = "host"
end
然后我尝试将与该查询匹配条件的所有行拉出并将其存储到数组中.
servers = Host.where(:realm => 'stage',:status => 'UP').pluck(:hostname)
但我每次都会收到这个错误.
ruby environments_are_okDev.rb /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/postgresql_adapter.rb:768:in `exec': PG::UndefinedTable: ERROR: relation "host" does not exist (ActiveRecord::StatementInvalid) LINE 5: WHERE a.attrelid = '"host"'::regclass ^ : SELECT a.attname,format_type(a.atttypid,a.atttypmod),pg_get_expr(d.adbin,d.adrelid),a.attnotnull,a.atttypid,a.atttypmod FROM pg_attribute a LEFT JOIN pg_attrdef d ON a.attrelid = d.adrelid AND a.attnum = d.adnum WHERE a.attrelid = '"host"'::regclass AND a.attnum > 0 AND NOT a.attisdropped ORDER BY a.attnum from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/postgresql_adapter.rb:768:in `exec_no_cache' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:138:in `block in exec_query' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:425:in `block in log' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activesupport-4.0.0/lib/active_support/notifications/instrumenter.rb:20:in `instrument' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/abstract_adapter.rb:420:in `log' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/postgresql/database_statements.rb:137:in `exec_query' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/postgresql_adapter.rb:915:in `column_deFinitions' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/postgresql/schema_statements.rb:174:in `columns' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/schema_cache.rb:114:in `block in prepare_default_proc' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/schema_cache.rb:56:in `yield' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/schema_cache.rb:56:in `default' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/connection_adapters/schema_cache.rb:56:in `columns' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/model_schema.rb:208:in `columns' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/model_schema.rb:247:in `column_names' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/relation/delegation.rb:60:in `block in method_missing' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/relation.rb:270:in `scoping' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/relation/delegation.rb:60:in `method_missing' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/relation/calculations.rb:152:in `block in pluck' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/relation/calculations.rb:151:in `map!' from /usr/local/rvm/gems/ruby-1.9.3-p448/gems/activerecord-4.0.0/lib/active_record/relation/calculations.rb:151:in `pluck' from environments_are_okDev.rb:51:in `run' from environments_are_okDev.rb:97:in `<main>'
我真的不明白为什么会发生这种情况,所以我试着用这个命令ActiveRecord :: Base.connection.tables看看数据库的样子,但我得到的只是一个空数组.我不确定会发生什么.我显然做错了什么,我只是弄不清楚是什么.请记住,这只是一个文件脚本.
编辑：
如果我使用ActiveRecord :: Base.connection.schema_names,我可以看到模式.这给了我一个数组=> [“db_stats”,“management”,“management_audit”,“public”]使用pgadmin,我知道我想要的表是在管理中,所以如何访问它？
