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
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M
P
Instance Public methods
column_spec(column, types)
# File activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb, line 9
def column_spec(column, types)
  spec = prepare_column_options(column, types)
  (spec.keys - [:name, :type]).each{ |k| spec[k].insert(0, "#{k}: ")}
  spec
end
migration_keys()

Lists the valid migration options

# File activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb, line 36
def migration_keys
  [:name, :limit, :precision, :scale, :default, :null]
end
prepare_column_options(column, types)

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

# File activerecord/lib/active_record/connection_adapters/abstract/schema_dumper.rb, line 18
def prepare_column_options(column, types)
  spec = {}
  spec[:name]      = column.name.inspect
  spec[:type]      = column.type.to_s
  spec[:null]      = 'false' unless column.null

  limit = column.limit || types[column.type][:limit]
  spec[:limit]     = limit.inspect if limit
  spec[:precision] = column.precision.inspect if column.precision
  spec[:scale]     = column.scale.inspect if column.scale

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

  spec
end