Class: DataMapper::Migration

Inherits:
Object
  • Object
show all
Includes:
SQL
Defined in:
lib/dm-migrations/migration.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(position, name, opts = {}, &block) ⇒ Migration

Returns a new instance of Migration.



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# File 'lib/dm-migrations/migration.rb', line 17

def initialize( position, name, opts = {}, &block )
  @position, @name = position, name
  @options = opts

  @database = DataMapper.repository(@options[:database] || :default)
  @adapter = @database.adapter

  if @adapter.respond_to?(:dialect)
    begin
      @adapter.extend(SQL.const_get("#{@adapter.dialect}"))
    rescue NameError
      raise "Unsupported Migration Adapter #{@adapter.class} with SQL dialect #{@adapter.dialect}"
    end
  else
    raise "Unsupported Migration Adapter #{@adapter.class}"
  end

  @verbose = @options.has_key?(:verbose) ? @options[:verbose] : true

  @up_action   = lambda {}
  @down_action = lambda {}

  instance_eval &block
end

Instance Attribute Details

#adapter ⇒ Object

Returns the value of attribute adapter.



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# File 'lib/dm-migrations/migration.rb', line 15

def adapter
  @adapter
end

#database ⇒ Object

Returns the value of attribute database.



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# File 'lib/dm-migrations/migration.rb', line 15

def database
  @database
end

#name ⇒ Object

Returns the value of attribute name.



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# File 'lib/dm-migrations/migration.rb', line 15

def name
  @name
end

#position ⇒ Object

Returns the value of attribute position.



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# File 'lib/dm-migrations/migration.rb', line 15

def position
  @position
end

Instance Method Details

#<=>(other) ⇒ Object

Orders migrations by position, so we know what order to run them in. First order by position, then by name, so at least the order is predictable.



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# File 'lib/dm-migrations/migration.rb', line 121

def <=> other
  if self.position == other.position
    self.name.to_s <=> other.name.to_s
  else
    self.position <=> other.position
  end
end

#create_index(table_name, *columns_and_options) ⇒ Object 



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# File 'lib/dm-migrations/migration.rb', line 103

def create_index(table_name, *columns_and_options)
  if columns_and_options.last.is_a?(Hash)
    opts = columns_and_options.pop
  else
    opts = {}
  end
  columns = columns_and_options.flatten

  opts[:name] ||= "#{opts[:unique] ? 'unique_' : ''}index_#{table_name}_#{columns.join('_')}"

  execute <<-SQL.compress_lines
    CREATE #{opts[:unique] ? 'UNIQUE ' : '' }INDEX #{quote_column_name(opts[:name])} ON
    #{quote_table_name(table_name)} (#{columns.map { |c| quote_column_name(c) }.join(', ') })
  SQL
end

#create_migration_info_table_if_needed ⇒ Object 



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# File 'lib/dm-migrations/migration.rb', line 162

def create_migration_info_table_if_needed
  save, @verbose = @verbose, false
  unless migration_info_table_exists?
    execute("CREATE TABLE #{migration_info_table} (#{migration_name_column} VARCHAR(255) UNIQUE)")
  end
  @verbose = save
end

#create_table(table_name, opts = {}, &block) ⇒ Object 



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# File 'lib/dm-migrations/migration.rb', line 89

def create_table(table_name, opts = {}, &block)
  execute TableCreator.new(@adapter, table_name, opts, &block).to_sql
end

#down(&block) ⇒ Object

define the actions that should be performed on a down migration



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# File 'lib/dm-migrations/migration.rb', line 48

def down(&block)
  @down_action = block
end

#drop_table(table_name, opts = {}) ⇒ Object 



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# File 'lib/dm-migrations/migration.rb', line 93

def drop_table(table_name, opts = {})
  execute "DROP TABLE #{@adapter.send(:quote_name, table_name.to_s)}"
end

#execute(sql, *bind_values) ⇒ Object

execute raw SQL



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# File 'lib/dm-migrations/migration.rb', line 83

def execute(sql, *bind_values)
  say_with_time(sql) do
    @adapter.execute(sql, *bind_values)
  end
end

#migration_info_table ⇒ Object

Quoted table name, for the adapter



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# File 'lib/dm-migrations/migration.rb', line 198

def migration_info_table
  @migration_info_table ||= quote_table_name('migration_info')
end

#migration_info_table_exists? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/dm-migrations/migration.rb', line 175

def migration_info_table_exists?
  adapter.storage_exists?('migration_info')
end

#migration_name_column ⇒ Object

Quoted ‘migration_name` column, for the adapter



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# File 'lib/dm-migrations/migration.rb', line 203

def migration_name_column
  @migration_name_column ||= quote_column_name('migration_name')
end

#migration_record ⇒ Object

Fetch the record for this migration out of the migration_info table



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# File 'lib/dm-migrations/migration.rb', line 180

def migration_record
  return [] unless migration_info_table_exists?
  @adapter.select("SELECT #{migration_name_column} FROM #{migration_info_table} WHERE #{migration_name_column} = #{quoted_name}")
end

#modify_table(table_name, opts = {}, &block) ⇒ Object 



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# File 'lib/dm-migrations/migration.rb', line 97

def modify_table(table_name, opts = {}, &block)
  TableModifier.new(@adapter, table_name, opts, &block).statements.each do |sql|
    execute(sql)
  end
end

#needs_down? ⇒ Boolean

True if the migration has already been run

Returns:

  • (Boolean) 


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# File 'lib/dm-migrations/migration.rb', line 192

def needs_down?
  return false unless migration_info_table_exists?
  ! migration_record.empty?
end

#needs_up? ⇒ Boolean

True if the migration needs to be run

Returns:

  • (Boolean) 


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# File 'lib/dm-migrations/migration.rb', line 186

def needs_up?
  return true unless migration_info_table_exists?
  migration_record.empty?
end

#perform_down ⇒ Object

un-do the migration by running the code in the #down block



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# File 'lib/dm-migrations/migration.rb', line 68

def perform_down
  result = nil
  if needs_down?
    # TODO: fix this so it only does transactions for databases that support create/drop
    # database.transaction.commit do
      say_with_time "== Performing Down Migration ##{position}: #{name}", 0 do
        result = @down_action.call
      end
      update_migration_info(:down)
    # end
  end
  result
end

#perform_up ⇒ Object

perform the migration by running the code in the #up block



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# File 'lib/dm-migrations/migration.rb', line 53

def perform_up
  result = nil
  if needs_up?
    # TODO: fix this so it only does transactions for databases that support create/drop
    # database.transaction.commit do
      say_with_time "== Performing Up Migration ##{position}: #{name}", 0 do
        result = @up_action.call
      end
      update_migration_info(:up)
    # end
  end
  result
end

#quote_column_name(column_name) ⇒ Object 



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# File 'lib/dm-migrations/migration.rb', line 212

def quote_column_name(column_name)
  # TODO: Fix this for 1.9 - can't use this hack to access a private method
  @adapter.send(:quote_name, column_name.to_s)
end

#quote_table_name(table_name) ⇒ Object 



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# File 'lib/dm-migrations/migration.rb', line 207

def quote_table_name(table_name)
  # TODO: Fix this for 1.9 - can't use this hack to access a private method
  @adapter.send(:quote_name, table_name.to_s)
end

#quoted_name ⇒ Object

Quote the name of the migration for use in SQL



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# File 'lib/dm-migrations/migration.rb', line 171

def quoted_name
  "'#{name}'"
end

#say(message, indent = 4) ⇒ Object

Output some text. Optional indent level



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# File 'lib/dm-migrations/migration.rb', line 130

def say(message, indent = 4)
  write "#{" " * indent} #{message}"
end

#say_with_time(message, indent = 2) ⇒ Object

Time how long the block takes to run, and output it with the message.



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# File 'lib/dm-migrations/migration.rb', line 135

def say_with_time(message, indent = 2)
  say(message, indent)
  result = nil
  time = Benchmark.measure { result = yield }
  say("-> %.4fs" % time.real, indent)
  result
end

#up(&block) ⇒ Object

define the actions that should be performed on an up migration



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# File 'lib/dm-migrations/migration.rb', line 43

def up(&block)
  @up_action = block
end

#update_migration_info(direction) ⇒ Object

Inserts or removes a row into the ‘migration_info` table, so we can mark this migration as run, or un-done



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# File 'lib/dm-migrations/migration.rb', line 149

def update_migration_info(direction)
  save, @verbose = @verbose, false

  create_migration_info_table_if_needed

  if direction.to_sym == :up
    execute("INSERT INTO #{migration_info_table} (#{migration_name_column}) VALUES (#{quoted_name})")
  elsif direction.to_sym == :down
    execute("DELETE FROM #{migration_info_table} WHERE #{migration_name_column} = #{quoted_name}")
  end
  @verbose = save
end

#write(text = "") ⇒ Object

output the given text, but only if verbose mode is on



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# File 'lib/dm-migrations/migration.rb', line 144

def write(text="")
  puts text if @verbose
end