Class: ActiveRecord::Base

Inherits:
Object
  • Object
show all
Defined in:
lib/active_record/connection_adapters/ibm_db_adapter.rb

Class Method Summary collapse

Class Method Details

.ibm_db_connection(config) ⇒ Object

Establishes a connection to a specified database using the credentials provided with the config argument. All the ActiveRecord objects will use this connection



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# File 'lib/active_record/connection_adapters/ibm_db_adapter.rb', line 89

def self.ibm_db_connection(config)
  # Attempts to load the Ruby driver IBM databases
  # while not already loaded or raises LoadError in case of failure.
  begin
    require 'ibm_db' unless defined? IBM_DB
  rescue LoadError
    raise LoadError, "Failed to load IBM_DB Ruby driver."
  end

  # Converts all +config+ keys to symbols
  config = config.symbolize_keys

  # Retrieves the database alias (local catalog name) or remote name
  # (for remote TCP/IP connections) from the +config+ hash
  # or raises ArgumentError in case of failure.
  if config.has_key?(:database)
    database = config[:database].to_s
  else
    raise ArgumentError, "Missing argument: a database name needs to be specified."
  end

  # Retrieves database user credentials from the +config+ hash
  # or raises ArgumentError in case of failure.
  if !config.has_key?(:username) || !config.has_key?(:password)
    raise ArgumentError, "Missing argument(s): Database configuration #{config} \
requires credentials: username and password"
  else
    username = config[:username].to_s
    password = config[:password].to_s
  end

  # Providing default schema (username) when not specified
  config[:schema] = config.has_key?(:schema) ? config[:schema].to_s : config[:username].to_s

  # Extract connection options from the database configuration
  # (in support to formatting, audit and billing purposes):
  # Retrieve database objects fields in lowercase
  conn_options = {IBM_DB::ATTR_CASE => IBM_DB::CASE_LOWER}
  config.each do |key, value|
    case key
      when :app_user        # Set connection's user info
        conn_options[IBM_DB::SQL_ATTR_INFO_USERID]     = value
      when :account         # Set connection's account info
        conn_options[IBM_DB::SQL_ATTR_INFO_ACCTSTR]    = value
      when :application     # Set connection's application info
        conn_options[IBM_DB::SQL_ATTR_INFO_APPLNAME]   = value
      when :workstation     # Set connection's workstation info
        conn_options[IBM_DB::SQL_ATTR_INFO_WRKSTNNAME] = value
    end
  end

  # Checks if a host name or address has been specified. If so, this implies a TCP/IP connection
  # Returns IBM_DB::Connection object upon succesful DB connection to the database
  # If otherwise the connection fails, +false+ is returned
  if config.has_key?(:host)
    # Retrieves the host address/name
    host = config[:host]
    # A net address connection requires a port. If no port has been specified, 50000 is used by default
    port = config[:port] || 50000
    # Connects to the database using the database, host, port, username and password specified
    connection = IBM_DB::connect "DRIVER={IBM DB2 ODBC DRIVER};\
                                  DATABASE=#{database};\
                                  HOSTNAME=#{host};\
                                  PORT=#{port};\
                                  PROTOCOL=TCPIP;\
                                  UID=#{username};\
                                  PWD=#{password};", '', '', conn_options
  else
    # No host implies a local catalog-based connection: +database+ represents catalog alias
    connection = IBM_DB::connect( database, username, password, conn_options )
  end

  # Verifies that the connection was succesfull
  if connection
    # Creates an instance of *IBM_DBAdapter* based on the +connection+
    # and credentials provided in +config+
    ConnectionAdapters::IBM_DBAdapter.new(connection, logger, config, conn_options)
  else
    # If the connection failed, it raises a Runtime error
    raise "Failed to connect to the [#{database}] due to: #{IBM_DB::conn_errormsg}"
  end
end