I do not use rails, and I am trying to use ActiveRecord to make it easier to work with an existing database. This is just a script, so I don't have database.yml or any other files. I established a connection to the database using
ActiveRecord::Base.establish_connection( adapter: 'postgresql', host: 'thehosthere', database: 'management', username: 'management_readonly', password: '', port: '5432' )
I am not very familiar with databases, so I’ll just tell you what I know about it. There are quite a few schemes. I need a schema that is a control schema that has a host table in it. I created the Host class in a script as follows:
class Host < ActiveRecord::Base self.table_name = "host" end
Then I try to print all the lines that match the criteria with this query and store them in an array.
servers = Host.where(:realm => 'stage', :status => 'UP').pluck(:hostname)
but I get this error every time.
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>'
I really don’t understand why this is happening, so I tried to see what the database looks like with this ActiveRecord::Base.connection.tables , but all I got is an empty array. I'm not sure what could happen. Obviously, I am doing something wrong, I just cannot understand that. Keep in mind that all this is in one script file.
Edit:
Therefore, I can see the diagrams if I use ActiveRecord::Base.connection.schema_names . This gives me an array => ["db_stats", "management", "management_audit", "public"] Using pgadmin, I know that the table I want is in control, so how do I access this?