The goal of this module is to move Adapter specific column definitions to the Adapter instead of having it in the schema dumper itself. This code represents the normal case. We can then redefine how certain data types may be handled in the schema dumper on the Adapter level by over-writing this code inside the database specific adapters

Methods
C
P
Instance Public methods
column_spec(column)

Source: show | on GitHub 

# File activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb, line 9
def column_spec(column)
  [schema_type_with_virtual(column), prepare_column_options(column)]
end
column_spec_for_primary_key(column)

Source: show | on GitHub 

# File activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb, line 13
def column_spec_for_primary_key(column)
  return {} if default_primary_key?(column)
  spec = { id: schema_type(column).inspect }
  spec.merge!(prepare_column_options(column).except!(:null))
  spec[:default] ||= "nil" if explicit_primary_key_default?(column)
  spec
end
prepare_column_options(column)

This can be overridden on an Adapter level basis to support other extended datatypes (Example: Adding an array option in the PostgreSQL::ColumnDumper)

Source: show | on GitHub 

# File activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb, line 24
def prepare_column_options(column)
  spec = {}

  if limit = schema_limit(column)
    spec[:limit] = limit
  end

  if precision = schema_precision(column)
    spec[:precision] = precision
  end

  if scale = schema_scale(column)
    spec[:scale] = scale
  end

  default = schema_default(column) if column.has_default?
  spec[:default] = default unless default.nil?

  spec[:null] = "false" unless column.null

  if collation = schema_collation(column)
    spec[:collation] = collation
  end

  spec[:comment] = column.comment.inspect if column.comment.present?

  spec
end