Class: Mongoid::Migration

Inherits:
Object
  • Object
show all
Defined in:
lib/mongoid_rails_migrations/active_record_ext/migrations.rb

Overview

Data migrations can manage the modification of data. It’s a solution to the common problem of modifying data between code revisions within a document oriented database.

Example of simple migration for a system dependency:

class AddBaselineSurveySchema < Mongoid::Migration
  def self.up
    SurveySchema.create(:label => 'Baseline Survey')
  end

  def self.down
    SurveySchema.where(:label => 'Baseline Survey').first.destroy
  end
end

Timestamped Migrations

By default, Rails generates migrations that look like:

20080717013526_your_migration_name.rb

The prefix is a generation timestamp (in UTC).

If you’d prefer to use numeric prefixes, you can turn timestamped migrations off by setting:

Mongoid.configure.timestamped_migrations = false

In environment.rb.

Constant Summary collapse

@@verbose = 
true

Class Method Summary collapse

Class Method Details

.announce(message) ⇒ Object 



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# File 'lib/mongoid_rails_migrations/active_record_ext/migrations.rb', line 125

def announce(message)
  version = defined?(@version) ? @version : nil

  text = "#{version} #{name}: #{message}"
  length = [0, 75 - text.length].max
  write "== %s %s" % [text, "=" * length]
end

.connection ⇒ Object 



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# File 'lib/mongoid_rails_migrations/active_record_ext/migrations.rb', line 153

def connection
  if ENV['MONGOID_CLIENT_NAME']
    Mongoid.client(ENV['MONGOID_CLIENT_NAME'])
  else
    Mongoid.default_client
  end
end

.down_with_benchmarks ⇒ Object

:nodoc:



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# File 'lib/mongoid_rails_migrations/active_record_ext/migrations.rb', line 71

def down_with_benchmarks #:nodoc:
  migrate(:down)
end

.migrate(direction) ⇒ Object

Execute this migration in the named direction



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# File 'lib/mongoid_rails_migrations/active_record_ext/migrations.rb', line 76

def migrate(direction)
  return unless respond_to?(direction)

  case direction
    when :up   then announce "migrating"
    when :down then announce "reverting"
  end

  result = nil
  time = Benchmark.measure { result = send("#{direction}_without_benchmarks") }

  case direction
    when :up   then announce "migrated (%.4fs)" % time.real; write
    when :down then announce "reverted (%.4fs)" % time.real; write
  end

  begin
    @@after_migrate.call(@@buffer_output, name, direction, false) if @@after_migrate
    @@buffer_output = nil
  rescue => e
    say("Error in after_migrate hook: #{e}")
  end
  result
end

.say(message, subitem = false) ⇒ Object 



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# File 'lib/mongoid_rails_migrations/active_record_ext/migrations.rb', line 133

def say(message, subitem=false)
  write "#{subitem ? "   ->" : "--"} #{message}"
end

.say_with_time(message) ⇒ Object 



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# File 'lib/mongoid_rails_migrations/active_record_ext/migrations.rb', line 137

def say_with_time(message)
  say(message)
  result = nil
  time = Benchmark.measure { result = yield }
  say "%.4fs" % time.real, :subitem
  say("#{result} rows", :subitem) if result.is_a?(Integer)
  result
end

.singleton_method_added(sym) ⇒ Object

Because the method added may do an alias_method, it can be invoked recursively. We use @ignore_new_methods as a guard to indicate whether it is safe for the call to proceed.



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# File 'lib/mongoid_rails_migrations/active_record_ext/migrations.rb', line 104

def singleton_method_added(sym) #:nodoc:
  return if defined?(@ignore_new_methods) && @ignore_new_methods
  begin
    @ignore_new_methods = true

    case sym
      when :up, :down
        singleton_class.send(:alias_method, "#{sym}_without_benchmarks".to_sym, sym)
        singleton_class.send(:alias_method, sym, "#{sym}_with_benchmarks".to_sym)
    end
  ensure
    @ignore_new_methods = false
  end
end

.suppress_messages ⇒ Object 



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# File 'lib/mongoid_rails_migrations/active_record_ext/migrations.rb', line 146

def suppress_messages
  save, self.verbose = verbose, false
  yield
ensure
  self.verbose = save
end

.up_with_benchmarks ⇒ Object

:nodoc:



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# File 'lib/mongoid_rails_migrations/active_record_ext/migrations.rb', line 67

def up_with_benchmarks #:nodoc:
  migrate(:up)
end

.write(text = "") ⇒ Object 



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# File 'lib/mongoid_rails_migrations/active_record_ext/migrations.rb', line 119

def write(text="")
  @@buffer_output ||=  ""
  @@buffer_output += text + "\n"
  puts(text) if verbose
end