package MySchema;

  use strict;

  use base qw(DBIx::Class::Schema::Loader);


  __PACKAGE__->loader_options(...);

  sub connection {

    my $class = shift;

    my $schema = $class->SUPER::connection(@_);

    my $classes = $schema->loader->classes;

    while (my($table, $schema_class) = each %$classes) {

       foreach my $column ($schema_class->columns) {

          # do something with $column

       }

    }

    $schema;

  }

俺の場合、ただ"_on"で終わるカラムを全てDateTimeにしたかったので、

   package MySchema::Base;

   use strict;


   sub has_datetime {

      my $class = shift;

      foreach my $column (@_) {

        $class->inflate_column($column, {

          inflate => sub { DateTime::format::Pg->parse_datetime(shift) },

          deflate => sub { DateTime::format::Pg->format_datetime(shift) },

        });

      }

   }

   package MySchema;

   __PACKAGE__->loader_options(..., additiona_base_classes => [ qw(MySchema::Base) ], ...);

で、さっきの"do something with..."のところで

    while (my($table, $schema_class) = each %$classes) {

       $schema_class->has_datetime(grep { /_on$/ } $schema_class->columns);

    }

ディモォォォォルトッ