Class: RailsInstaller::Database

Inherits:
Object
  • Object
show all
Defined in:
lib/rails-installer/databases.rb

Overview

Parent class for database plugins for the installer. To create a new database handler, subclass this class and define a yml class and optionally a create_database method.

Direct Known Subclasses

Mysql, Postgresql, Sqlite

Defined Under Namespace

Classes: Mysql, Postgresql, Sqlite

Constant Summary collapse

@@db_map = 
Hash.new(self)

Class Method Summary collapse

Class Method Details

.backup(installer) ⇒ Object

Back up the database. This is fully DB and schema agnostic. It serializes all tables to a single YAML file.



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# File 'lib/rails-installer/databases.rb', line 35

def self.backup(installer)
  return unless connect(installer)
  
  interesting_tables = ActiveRecord::Base.connection.tables.sort - ['sessions']
  backup_dir = File.join(installer.install_directory, 'db', 'backup')
  FileUtils.mkdir_p backup_dir
  backup_file = File.join(backup_dir, "backup-#{Time.now.strftime('%Y%m%d-%H%M')}.yml")

  installer.message "Backing up to #{backup_file}"
  
  data = {}
  interesting_tables.each do |tbl|
    data[tbl] = ActiveRecord::Base.connection.select_all("select * from #{tbl}")
  end

  File.open(backup_file,'w') do |file|
    YAML.dump data, file
  end
end

.connect(installer) ⇒ Object

Connect to the database (using the ‘database.yml’ generated by the yml method). Returns true if the database already exists, and false if the database doesn’t exist yet.



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# File 'lib/rails-installer/databases.rb', line 14

def self.connect(installer)
  database_yml = File.read File.join(installer.install_directory, 'config', 'database.yml') rescue nil
  database_yml ||= yml(installer)
  
  environment = ENV['RAILS_ENV'] || 'development' # Mirror Rails' default.
  
  ActiveRecord::Base.establish_connection( 
    YAML.load(database_yml)[environment])
  begin
    tables = ActiveRecord::Base.connection.tables
    if tables.size > 0
      return true
    end
  rescue Exception
    # okay
  end
  return false
end

.create(installer) ⇒ Object

Create the database, including schema creation. This should be generic enough that database-specific drivers don’t need to override it.

It calls create_database to actually build a new DB from scratch if needed.



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# File 'lib/rails-installer/databases.rb', line 107

def self.create(installer)
  installer.message "Checking database"
  if connect(installer)
    installer.message "Database exists, preparing for upgrade"
    return
  end

  installer.message "Creating initial database"
  
  create_database(installer)
  
  schema_file = File.join(installer.install_directory,'db',"schema.#{installer.config['database']}.sql")
  schema = File.read(schema_file)
  
  # Remove comments and extra blank lines
  schema = schema.split(/\n/).map{|l| l.gsub(/^--.*/,'')}.select{|l| !(l=~/^$/)}.join("\n")
  
  schema.split(/;\n/).each do |command|
    ActiveRecord::Base.connection.execute(command)
  end
end

.create_database(installer) ⇒ Object

Create a new database from scratch. Some DBs, like SQLite, don’t need this. Others will need to override this and call the DB’s “create new database” command.



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# File 'lib/rails-installer/databases.rb', line 132

def self.create_database(installer)
  # nothing
end

.database_yml(installer) ⇒ Object

Create a ‘database.yml’ file, using the data from yml.



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# File 'lib/rails-installer/databases.rb', line 93

def self.database_yml(installer)
  yml_file = File.join(installer.install_directory,'config','database.yml')
  return if File.exists? yml_file
  
  File.open(yml_file,'w') do |f|
    f.write(yml(installer))
  end
end

.db_host(installer) ⇒ Object

Database host name



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# File 'lib/rails-installer/databases.rb', line 150

def self.db_host(installer)
  installer.config['db_host'] || 'localhost'
end

.db_name(installer) ⇒ Object

Database name



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# File 'lib/rails-installer/databases.rb', line 160

def self.db_name(installer)
  installer.config['db_name'] || installer.app_name
end

.db_user(installer) ⇒ Object

Database user name



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# File 'lib/rails-installer/databases.rb', line 155

def self.db_user(installer)
  installer.config['db_user'] || ENV['USER'] || installer.app_name 
end

.dbs ⇒ Object 



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# File 'lib/rails-installer/databases.rb', line 145

def self.dbs
  @@db_map
end

.inherited(sub) ⇒ Object

Inheritence hook



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# File 'lib/rails-installer/databases.rb', line 137

def self.inherited(sub)
  name = sub.to_s.gsub(/^.*::/,'').gsub(/([A-Z])/) do |match|
    "_#{match.downcase}"
  end.gsub(/^_/,'')

  @@db_map[name] = sub
end

.restore(installer, filename) ⇒ Object

Restore a backup created by backup. Deletes all data before importing.



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# File 'lib/rails-installer/databases.rb', line 57

def self.restore(installer, filename)
  connect(installer)
  data = YAML.load(File.read(filename))
  
  installer.message "Restoring data"
  data.each_key do |table|
    if table == 'schema_info'
      ActiveRecord::Base.connection.execute("delete from schema_info")
      ActiveRecord::Base.connection.execute("insert into schema_info (version) values (#{data[table].first['version']})")
    else
      installer.message " Restoring table #{table} (#{data[table].size})"

      # Create a temporary model to talk to the DB
      eval %Q{
      class TempClass < ActiveRecord::Base
        set_table_name '#{table}'
        reset_column_information
      end
      }
      
      TempClass.delete_all
            
      data[table].each do |record|
        r = TempClass.new(record)
        r.id = record['id'] if record.has_key?('id')
        r.save
      end
      
      if ActiveRecord::Base.connection.respond_to?(:reset_pk_sequence!)
        ActiveRecord::Base.connection.reset_pk_sequence!(table)
      end
    end
  end
end