Oracle enhanced adapter for ActiveRecord
Oracle enhanced ActiveRecord adapter provides Oracle database access from Ruby on Rails applications. Oracle enhanced adapter can be used from Ruby on Rails versions 2.3.x and 3.x and it is working with Oracle database versions 10g and 11g.
When using Ruby on Rails version 3 then in Gemfile include
gem 'activerecord-oracle_enhanced-adapter', '~> 1.4.0'
where instead of 1.4.0 you can specify any other desired version. It is recommended to specify version with ~> which means that use specified version or later patch versions (in this example any later 1.4.x version but not 1.5.x version). Oracle enhanced adapter maintains API backwards compatibility during patch version upgrades and therefore it is safe to always upgrade to latest patch version.
If you would like to use latest adapter version from github then specify
gem 'activerecord-oracle_enhanced-adapter', :git => 'git://github.com/rsim/oracle-enhanced.git'
If you are using MRI 1.8 or 1.9 Ruby implementation then you need to install ruby-oci8 gem as well as Oracle client, e.g. Oracle Instant Client. Include in Gemfile also ruby-oci8:
gem 'ruby-oci8', '~> 2.1.0'
If you are using JRuby then you need to download latest Oracle JDBC driver - either ojdbc6.jar for Java 6 or ojdbc5.jar for Java 5. And copy this file to one of these locations:
- in
./libdirectory of Rails application - in some directory which is in
PATH - in
JRUBY_HOME/libdirectory - or include path to JDBC driver jar file in Java
CLASSPATH
After specifying necessary gems in Gemfile run
bundle install
to install the adapter (or later run bundle update to force updating to latest version).
If you don't use Bundler in Rails 2 application then you need to specify gems in config/environment.rb, e.g.
Rails::Initializer.run do |config|
#...
config.gem 'activerecord-oracle_enhanced-adapter', :lib => "active_record/connection_adapters/oracle_enhanced_adapter"
config.gem 'ruby-oci8'
#...
end
But it is recommended to use Bundler for gem version management also for Rails 2.3 applications (search for instructions in Google).
If you want to use ActiveRecord and Oracle enhanced adapter without Rails and Bundler then install it just as a gem:
gem install activerecord-oracle_enhanced-adapter
In Rails application config/database.yml use oracle_enhanced as adapter name, e.g.
development:
adapter: oracle_enhanced
database: xe
username: user
password: secret
If you're connecting to a service name, indicate the service with a leading slash on the database parameter:
development:
adapter: oracle_enhanced
database: /xe
username: user
password: secret
If TNS_ADMIN environment variable is pointing to directory where tnsnames.ora file is located then you can use TNS connection name in database parameter. Otherwise you can directly specify database host, port (defaults to 1521) and database name in the following way:
development:
adapter: oracle_enhanced
host: localhost
port: 1521
database: xe
username: user
password: secret
or you can use Oracle specific format in database parameter:
development:
adapter: oracle_enhanced
database: //localhost:1521/xe
username: user
password: secret
or you can even use Oracle specific TNS connection description:
development:
adapter: oracle_enhanced
database: "(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=tcp)(HOST=localhost)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=xe)))"
username: user
password: secret
If you deploy JRuby on Rails application in Java application server that supports JNDI connections then you can specify JNDI connection as well:
development:
adapter: oracle_enhanced
jndi: "jdbc/jndi_connection_name"
To use jndi with Tomcat you need to set the accessToUnderlyingConnectionAllowed to true property on the pool. See the Tomcat Documentation for reference.
You can find other available database.yml connection parameters in oracle_enhanced_adapter.rb. There are many NLS settings as well as some other Oracle session settings.
If you want to change Oracle enhanced adapter default settings then create initializer file e.g. config/initializers/oracle.rb specify there necessary defaults, e.g.:
# It is recommended to set time zone in TZ environment variable so that the same timezone will be used by Ruby and by Oracle session
ENV['TZ'] = 'UTC'
ActiveSupport.on_load(:active_record) do
ActiveRecord::ConnectionAdapters::OracleEnhancedAdapter.class_eval do
# id columns and columns which end with _id will always be converted to integers
self.emulate_integers_by_column_name = true
# DATE columns which include "date" in name will be converted to Date, otherwise to Time
self.emulate_dates_by_column_name = true
# true and false will be stored as 'Y' and 'N'
self.emulate_booleans_from_strings = true
# start primary key sequences from 1 (and not 10000) and take just one next value in each session
self.default_sequence_start_value = "1 NOCACHE INCREMENT BY 1"
# other settings ...
end
end
In case of Rails 2 application you do not need to use ActiveSupport.on_load(:active_record) do ... end around settings code block.
See other adapter settings in oracle_enhanced_adapter.rb.
If you want to put Oracle enhanced adapter on top of existing schema tables then there are several methods how to override ActiveRecord defaults, see example:
class Employee < ActiveRecord::Base
# specify schema and table name
set_table_name "hr.hr_employees"
# specify primary key name
set_primary_key "employee_id"
# specify sequence name
set_sequence_name "hr.hr_employee_s"
# set which DATE columns should be converted to Ruby Date
set_date_columns :hired_on, :birth_date_on
# set which DATE columns should be converted to Ruby Time
set_datetime_columns :last_login_time
# set which VARCHAR2 columns should be converted to true and false
set_boolean_columns :manager, :active
# set which columns should be ignored in ActiveRecord
ignore_table_columns :attribute1, :attribute2
end
You can also access remote tables over database link using
set_table_name "hr_employees@db_link"
If you have legacy schema and you are not allowed to do direct INSERTs, UPDATEs and DELETEs in legacy schema tables and need to use existing PL/SQL procedures for create, updated, delete operations then you should add ruby-plsql gem to your application and then define custom create, update and delete methods, see example:
class Employee < ActiveRecord::Base
# when defining create method then return ID of new record that will be assigned to id attribute of new object
set_create_method do
plsql.employees_pkg.create_employee(
:p_first_name => first_name,
:p_last_name => last_name,
:p_employee_id => nil
)[:p_employee_id]
end
set_update_method do
plsql.employees_pkg.update_employee(
:p_employee_id => id,
:p_first_name => first_name,
:p_last_name => last_name
)
end
set_delete_method do
plsql.employees_pkg.delete_employee(
:p_employee_id => id
)
end
end
In addition in config/initializers/oracle.rb initializer specify that ruby-plsql should use ActiveRecord database connection:
plsql.activerecord_class = ActiveRecord::Base
Every edition of Oracle database includes Oracle Text option for free which provides several full text indexing capabilities. Therefore in Oracle database case you don’t need external full text indexing and searching engines which can simplify your application deployment architecture.
To create simple single column index create migration with, e.g.
add_context_index :posts, :title
and you can remove context index with
remove_context_index :posts, :title
Include in class definition
has_context_index
and then you can do full text search with
Post.contains(:title, 'word')
You can create index on several columns (which will generate additional stored procedure for providing XML document with specified columns to indexer):
add_context_index :posts, [:title, :body]
And you can search either in all columns or specify in which column you want to search (as first argument you need to specify first column name as this is the column which is referenced during index creation):
Post.contains(:title, 'word')
Post.contains(:title, 'word within title')
Post.contains(:title, 'word within body')
See Oracle Text documentation for syntax that you can use in CONTAINS function in SELECT WHERE clause.
You can also specify some dummy main column name when creating multiple column index as well as specify to update index automatically after each commit (as otherwise you need to synchronize index manually or schedule periodic update):
add_context_index :posts, [:title, :body], :index_column => :all_text, :sync => 'ON COMMIT'
Post.contains(:all_text, 'word')
Or you can specify that index should be updated when specified columns are updated (e.g. in ActiveRecord you can specify to trigger index update when created_at or updated_at columns are updated). Otherwise index is updated only when main index column is updated.
add_context_index :posts, [:title, :body], :index_column => :all_text,
:sync => 'ON COMMIT', :index_column_trigger_on => [:created_at, :updated_at]
And you can even create index on multiple tables by providing SELECT statements which should be used to fetch necessary columns from related tables:
add_context_index :posts,
[:title, :body,
# specify aliases always with AS keyword
"SELECT comments.author AS comment_author, comments.body AS comment_body FROM comments WHERE comments.post_id = :id"
],
:name => 'post_and_comments_index',
:index_column => :all_text,
:index_column_trigger_on => [:updated_at, :comments_count],
:sync => 'ON COMMIT'
# search in any table columns
Post.contains(:all_text, 'word')
# search in specified column
Post.contains(:all_text, "aaa within title")
Post.contains(:all_text, "bbb within comment_author")
Since version R11G1 Oracle database allows adding computed Virtual Columns to the table. They can be used as normal fields in the queries, in the foreign key contstraints and to partitioning data.
To define virtual column you can use virtual method in the create_table block, providing column expression in the :as option:
create_table :mytable do |t|
t.decimal :price, :precision => 15, :scale => 2
t.decimal :quantity, :precision => 15, :scale => 2
t.virtual :amount, :as => 'price * quantity'
end
Oracle tries to predict type of the virtual column, based on its expression but sometimes it is necessary to state type explicitly.
This can be done by providing :type option to the virtual method:
...
t.virtual :amount_2, :as => 'ROUND(price * quantity,2)', :type => :decimal, :precision => 15, :scale => 2
t.virtual :amount_str, :as => "TO_CHAR(quantity) || ' x ' || TO_CHAR(price) || ' USD = ' || TO_CHAR(quantity*price) || ' USD'",
:type => :string, :limit => 100
...
It is possible to add virtual column to existing table:
add_column :mytable, :amount_4, :virtual, :as => 'ROUND(price * quantity,4)', :precision => 38, :scale => 4
You can use the same options here as in the create_table virtual method.
Changing virtual columns is also possible:
change_column :mytable, :amount, :virtual, :as => 'ROUND(price * quantity,0)', :type => :integer
Virtual columns allowed in the foreign key constraints. For example it can be used to force foreign key constraint on polymorphic association:
create_table :comments do |t|
t.string :subject_type
t.integer :subject_id
t.virtual :subject_photo_id, :as => "CASE subject_type WHEN 'Photo' THEN subject_id END"
t.virtual :subject_event_id, :as => "CASE subject_type WHEN 'Event' THEN subject_id END"
end
add_foreign_key :comments, :photos, :column => :subject_photo_id
add_foreign_key :comments, :events, :column => :subject_event_id
For backward compatibility reasons it is possible to use :default option in the create_table instead of :as option.
But this is deprecated and may be removed in the future version.
There are several additional schema statements and data types available that you can use in database migrations:
-
add_foreign_keyandremove_foreign_keyfor foreign key definition (and they are also dumped indb/schema.rb) -
add_synonymandremove_synonymfor synonym definition (and they are also dumped indb/schema.rb) -
You can create table with primary key trigger using
:primary_key_trigger => trueoption forcreate_table -
You can define columns with
rawtype which maps to Oracle'sRAWtype -
You can add table and column comments with
:commentoption -
Default tablespaces can be specified for tables, indexes, clobs and blobs, for example:
ActiveRecord::ConnectionAdapters::OracleEnhancedAdapter.default_tablespaces = {:clob => 'TS_LOB', :blob => 'TS_LOB', :index => 'TS_INDEX', :table => 'TS_DATA'}
Please verify that
-
Oracle Instant Client is installed correctly Can you connect to database using sqlnet?
-
ruby-oci8 is installed correctly Try something like:
ruby -rubygems -e "require 'oci8'; OCI8.new('username','password','database').exec('select * from dual') do |r| puts r.join(','); end"to verify that ruby-oci8 is working
-
Verify that activerecord-oracle_enhanced-adapter is working from irb
require 'rubygems' gem 'activerecord' gem 'activerecord-oracle_enhanced-adapter' require 'active_record' ActiveRecord::Base.establish_connection(:adapter => "oracle_enhanced", :database => "database",:username => "user",:password => "password")and see if it is successful (use your correct database, username and password)
Oracle Instant Client and ruby-oci8 requires that several environment variables are set:
LD_LIBRARY_PATH(on Linux) orDYLD_LIBRARY_PATH(on Mac) should point to Oracle Instant Client directory (where Oracle client shared libraries are located)TNS_ADMINshould point to directory wheretnsnames.orafile is locatedNLS_LANGshould specify which territory and language NLS settings to use and which character set to use (e.g."AMERICAN_AMERICA.UTF8")
If this continues to throw "OCI Library Initialization Error (OCIError)", you might also need
ORACLE_HOMEset to full Oracle client installation directory
When Apache with Phusion Passenger (mod_passenger or previously mod_rails) is used for Rails application deployment then by default Ruby is launched without environment variables that you have set in shell profile scripts (e.g. .profile). Therefore it is necessary to set environment variables in one of the following ways:
- Create wrapper script as described in Phusion blog or RayApps::Blog
- Set environment variables in the file which is used by Apache before launching Apache worker processes - on Linux it typically is envvars file (look in apachectl or apache2ctl script where it is looking for envvars file) or /System/Library/LaunchDaemons/org.apache.httpd.plist on Mac OS X. See the following discussion thread for more hints.
See RUNNING_TESTS.md for information how to set up environment and run Oracle enhanced adapter unit tests.
- Source code: http://github.com/rsim/oracle-enhanced
- Bug reports / Feature requests / Pull requests: http://github.com/rsim/oracle-enhanced/issues
- Discuss at Oracle enhanced adapter group: http://groups.google.com/group/oracle-enhanced
- Blog posts about Oracle enhanced adapter can be found at http://blog.rayapps.com/category/oracle_enhanced
(The MIT License)
Copyright (c) 2008-2011 Graham Jenkins, Michael Schoen, Raimonds Simanovskis
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