Module: ActiveRecord::Migration::Ext::ChangeTableMoveToEnd

Included in:
ActiveRecord::Migration
Defined in:
lib/active_record/migration/ext/change_table_move_to_end.rb

Defined Under Namespace

Modules: CommandRecorder

Instance Method Summary collapse

Instance Method Details

#change_table_move_to_end(table_name, &block) ⇒ Object

Provides a convenient way to reorder your columns, since you can't use after: 'other_field' when using PostgreSQL (dba.stackexchange.com/questions/3276/how-can-i-specify-the-position-for-a-new-column-in-postgresql)

Adds a new copy of the given columns, copies data into the new columns, then removes the old columns, and renames the new columns to the original names.

Does not re-add indexes.



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# File 'lib/active_record/migration/ext/change_table_move_to_end.rb', line 70

def change_table_move_to_end(table_name, &block)
  add_orig_columns = recorder_record do
    change_table table_name, &block
  end
  add_orig_columns.extend(CommandRecorder::Ext)
  # pp add_orig_columns.commands

  say_with_time_and_silence "Moving to end of #{table_name}: #{add_orig_columns.column_names.join(', ')}" do
    # Add a new copy of the given columns (with temporary names)
    add_new_columns = add_orig_columns.add_suffix('_copy').extend(CommandRecorder::Ext)
    # pp add_new_columns.commands
    add_new_columns.replay(self)

    # Copy data into the new columns
    column_names_to_temp_names = add_orig_columns.column_names.map do |name|
      [name, "#{name}_copy"]
    end
    reversible do |dir|
      dir.up do
        execute <<~END
          update #{table_name}
            set
              #{column_names_to_temp_names.map do |orig, temp|
                "#{temp} = #{orig}"
              end.join(",\n")}
            ;
        END
      end
      dir.down do
        execute <<~END
          update #{table_name}
            set
              #{column_names_to_temp_names.map do |orig, temp|
                "#{orig} = #{temp}"
              end.join(",\n")}
            ;
        END
      end
    end

    # Remove the old columns
    # pp add_orig_columns.inverse.commands
    add_orig_columns.inverse.replay(self)

    # Rename the new columns to the original names.
    add_new_columns.change_add_column_to_rename do |name|
      name.sub(/_copy$/, '')
    end.replay(self)
  end
end

#say_with_time_and_silence(message, &block) ⇒ Object 



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# File 'lib/active_record/migration/ext/change_table_move_to_end.rb', line 121

def say_with_time_and_silence(message, &block)
  say_with_time message do
    suppress_messages(&block)
  end
end