DBIx::Class::InflateColumn - Automatically create references from column data

DBIx-Class documentation Contained in the DBIx-Class distribution.

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NAME

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DBIx::Class::InflateColumn - Automatically create references from column data

SYNOPSIS

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    # In your table classes
    __PACKAGE__->inflate_column('column_name', {
        inflate => sub { ... },
        deflate => sub { ... },
    });

DESCRIPTION

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This component translates column data into references, i.e. "inflating" the column data. It also "deflates" references into an appropriate format for the database.

It can be used, for example, to automatically convert to and from DateTime objects for your date and time fields. There's a convenience component to actually do that though, try DBIx::Class::InflateColumn::DateTime.

It will handle all types of references except scalar references. It will not handle scalar values, these are ignored and thus passed through to SQL::Abstract. This is to allow setting raw values to "just work". Scalar references are passed through to the database to deal with, to allow such settings as \'year + 1' and \'DEFAULT' to work.

If you want to filter plain scalar values and replace them with something else, see DBIx::Class::FilterColumn.

METHODS

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inflate_column

Instruct DBIx::Class to inflate the given column.

In addition to the column name, you must provide inflate and deflate methods. The inflate method is called when you access the field, while the deflate method is called when the field needs to used by the database.

For example, if you have a table events with a timestamp field named insert_time, you could inflate the column in the corresponding table class using something like:

    __PACKAGE__->inflate_column('insert_time', {
        inflate => sub { DateTime::Format::Pg->parse_datetime(shift); },
        deflate => sub { DateTime::Format::Pg->format_datetime(shift); },
    });

(Replace DateTime::Format::Pg with the appropriate module for your database, or consider DateTime::Format::DBI.)

The coderefs you set for inflate and deflate are called with two parameters, the first is the value of the column to be inflated/deflated, the second is the row object itself. Thus you can call ->result_source->schema->storage->dbh in your inflate/defalte subs, to feed to DateTime::Format::DBI.

In this example, calls to an event's insert_time accessor return a DateTime object. This DateTime object is later "deflated" when used in the database layer.

get_inflated_column

  my $val = $obj->get_inflated_column($col);

Fetch a column value in its inflated state. This is directly analogous to get_column in DBIx::Class::Row in that it only fetches a column already retrieved from the database, and then inflates it. Throws an exception if the column requested is not an inflated column.

set_inflated_column

  my $copy = $obj->set_inflated_column($col => $val);

Sets a column value from an inflated value. This is directly analogous to set_column in DBIx::Class::Row.

store_inflated_column

  my $copy = $obj->store_inflated_column($col => $val);

Sets a column value from an inflated value without marking the column as dirty. This is directly analogous to store_column in DBIx::Class::Row.

SEE ALSO

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DBIx::Class::Core - This component is loaded as part of thecore DBIx::Class components; generally there is no need to load it directly

AUTHOR

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Matt S. Trout <mst@shadowcatsystems.co.uk>

CONTRIBUTORS

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Daniel Westermann-Clark <danieltwc@cpan.org> (documentation)

Jess Robinson <cpan@desert-island.demon.co.uk>

LICENSE

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You may distribute this code under the same terms as Perl itself.

DBIx-Class documentation Contained in the DBIx-Class distribution. 
package DBIx::Class::InflateColumn;

use strict;
use warnings;

use base qw/DBIx::Class::Row/;


sub inflate_column {
  my ($self, $col, $attrs) = @_;

  my $colinfo = $self->column_info($col);

  $self->throw_exception("InflateColumn does not work with FilterColumn")
    if $self->isa('DBIx::Class::FilterColumn') &&
      defined $colinfo->{_filter_info};

  $self->throw_exception("No such column $col to inflate")
    unless $self->has_column($col);
  $self->throw_exception("inflate_column needs attr hashref")
    unless ref $attrs eq 'HASH';
  $colinfo->{_inflate_info} = $attrs;
  my $acc = $colinfo->{accessor};
  $self->mk_group_accessors('inflated_column' => [ (defined $acc ? $acc : $col), $col]);
  return 1;
}

sub _inflated_column {
  my ($self, $col, $value) = @_;
  return $value unless defined $value; # NULL is NULL is NULL
  my $info = $self->column_info($col)
    or $self->throw_exception("No column info for $col");
  return $value unless exists $info->{_inflate_info};
  my $inflate = $info->{_inflate_info}{inflate};
  $self->throw_exception("No inflator for $col") unless defined $inflate;
  return $inflate->($value, $self);
}

sub _deflated_column {
  my ($self, $col, $value) = @_;
#  return $value unless ref $value && blessed($value); # If it's not an object, don't touch it
  ## Leave scalar refs (ala SQL::Abstract literal SQL), untouched, deflate all other refs
  return $value unless (ref $value && ref($value) ne 'SCALAR');
  my $info = $self->column_info($col) or
    $self->throw_exception("No column info for $col");
  return $value unless exists $info->{_inflate_info};
  my $deflate = $info->{_inflate_info}{deflate};
  $self->throw_exception("No deflator for $col") unless defined $deflate;
  return $deflate->($value, $self);
}


sub get_inflated_column {
  my ($self, $col) = @_;
  $self->throw_exception("$col is not an inflated column")
    unless exists $self->column_info($col)->{_inflate_info};
  return $self->{_inflated_column}{$col}
    if exists $self->{_inflated_column}{$col};

  my $val = $self->get_column($col);
  return $val if ref $val eq 'SCALAR';  #that would be a not-yet-reloaded sclarref update

  return $self->{_inflated_column}{$col} = $self->_inflated_column($col, $val);
}


sub set_inflated_column {
  my ($self, $col, $inflated) = @_;
  $self->set_column($col, $self->_deflated_column($col, $inflated));
#  if (blessed $inflated) {
  if (ref $inflated && ref($inflated) ne 'SCALAR') {
    $self->{_inflated_column}{$col} = $inflated;
  } else {
    delete $self->{_inflated_column}{$col};
  }
  return $inflated;
}


sub store_inflated_column {
  my ($self, $col, $inflated) = @_;
#  unless (blessed $inflated) {
  unless (ref $inflated && ref($inflated) ne 'SCALAR') {
      delete $self->{_inflated_column}{$col};
      $self->store_column($col => $inflated);
      return $inflated;
  }
  delete $self->{_column_data}{$col};
  return $self->{_inflated_column}{$col} = $inflated;
}


1;