123456789_123456789_123456789_123456789_123456789_

Class: ActiveRecord::SchemaMigration

Do not use. This class is for internal use only.
Relationships & Source Files
Namespace Children
Classes:
NullSchemaMigration
Inherits: Object
Defined in: activerecord/lib/active_record/schema_migration.rb

Overview

This class is used to create a table that keeps track of which migrations have been applied to a given database. When a migration is run, its schema number is inserted in to the schema migrations table so it doesn’t need to be executed the next time.

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Constructor Details

.new(connection) ⇒ SchemaMigration

[ GitHub ] 

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 14



def initialize(connection)
  @connection = connection
  @arel_table = Arel::Table.new(table_name)
end


  







Instance Attribute Details



  

    #arel_table   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 12



attr_reader :connection, :arel_table


  








  

    #connection   (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 12



attr_reader :connection, :arel_table


  








  

    #table_exists?  ⇒ Boolean  (readonly)
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 85



def table_exists?
  connection.data_source_exists?(table_name)
end


  







Instance Method Details



  

    #count  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 78



def count
  sm = Arel::SelectManager.new(arel_table)
  sm.project(*Arel::Nodes::Count.new([Arel.star]))

  connection.select_values(sm, "#{self.class} Count").first
end


  








  

    #create_table  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 46



def create_table
  unless connection.table_exists?(table_name)
    connection.create_table(table_name, id: false) do |t|
      t.string :version, **connection.internal_string_options_for_primary_key
    end
  end
end


  








  

    #create_version(version)  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 19



def create_version(version)
  im = Arel::InsertManager.new(arel_table)
  im.insert(arel_table[primary_key] => version)
  connection.insert(im, "#{self.class} Create", primary_key, version)
end


  








  

    #delete_all_versions  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 32



def delete_all_versions
  versions.each do |version|
    delete_version(version)
  end
end


  








  

    #delete_version(version)  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 25



def delete_version(version)
  dm = Arel::DeleteManager.new(arel_table)
  dm.wheres = [arel_table[primary_key].eq(version)]

  connection.delete(dm, "#{self.class} Destroy")
end


  








  

    #drop_table  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 54



def drop_table
  connection.drop_table table_name, if_exists: true
end


  








  

    #integer_versions  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 74



def integer_versions
  versions.map(&:to_i)
end


  








  

    #normalize_migration_number(number)  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 58



def normalize_migration_number(number)
  "%.3d" % number.to_i
end


  








  

    #normalized_versions  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 62



def normalized_versions
  versions.map { |v| normalize_migration_number v }
end


  








  

    #primary_key  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 38



def primary_key
  "version"
end


  








  

    #table_name  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 42



def table_name
  "#{ActiveRecord::Base.table_name_prefix}#{ActiveRecord::Base.schema_migrations_table_name}#{ActiveRecord::Base.table_name_suffix}"
end


  








  

    #versions  
  

  [ GitHub ]


  

  


# File 'activerecord/lib/active_record/schema_migration.rb', line 66



def versions
  sm = Arel::SelectManager.new(arel_table)
  sm.project(arel_table[primary_key])
  sm.order(arel_table[primary_key].asc)

  connection.select_values(sm, "#{self.class} Load")
end