package DBIx::Class::Relationship::Base;
use strict;
use warnings;
use base qw/Class::Data::Inheritable/;
__PACKAGE__->mk_classdata('_relationships', { } );
=head1 NAME
DBIx::Class::Relationship::Base - Inter-table relationships
=head1 SYNOPSIS
=head1 DESCRIPTION
This class handles relationships between the tables in your database
model. It allows your to set up relationships, and to perform joins
on searches.
=head1 METHODS
=over 4
=item add_relationship
__PACKAGE__->add_relationship('relname', 'Foreign::Class', $cond, $attrs);
The condition needs to be an SQL::Abstract-style representation of the
join between the tables - for example if you're creating a rel from Foo to Bar
{ 'foreign.foo_id' => 'self.id' }
will result in a JOIN clause like
foo me JOIN bar bar ON bar.foo_id = me.id
=cut
sub add_relationship {
my ($class, $rel, $f_class, $cond, $attrs) = @_;
die "Can't create relationship without join condition" unless $cond;
$attrs ||= {};
eval "require $f_class;";
my %rels = %{ $class->_relationships };
$rels{$rel} = { class => $f_class,
cond => $cond,
attrs => $attrs };
$class->_relationships(\%rels);
#warn %{$f_class->_columns};
return unless eval { %{$f_class->_columns}; }; # Foreign class not loaded
eval { $class->_resolve_join($rel, 'me') };
if ($@) { # If the resolve failed, back out and re-throw the error
delete $rels{$rel}; #
$class->_relationships(\%rels);
$class->throw("Error creating relationship $rel: $@");
}
1;
}
sub _resolve_join {
my ($class, $join, $alias) = @_;
if (ref $join eq 'ARRAY') {
return map { $class->_resolve_join($_, $alias) } @$join;
} elsif (ref $join eq 'HASH') {
return map { $class->_resolve_join($_, $alias),
$class->_relationships->{$_}{class}->_resolve_join($join->{$_}, $_) }
keys %$join;
} elsif (ref $join) {
$class->throw("No idea how to resolve join reftype ".ref $join);
} else {
my $rel_obj = $class->_relationships->{$join};
$class->throw("No such relationship ${join}") unless $rel_obj;
my $j_class = $rel_obj->{class};
my %join = (_action => 'join',
_aliases => { 'self' => $alias, 'foreign' => $join },
_classes => { $alias => $class, $join => $j_class });
my $j_cond = $j_class->resolve_condition($rel_obj->{cond}, \%join);
return [ { $join => $j_class->_table_name,
-join_type => $rel_obj->{attrs}{join_type} || '' }, $j_cond ];
}
}
sub resolve_condition {
my ($self, $cond, $attrs) = @_;
if (ref $cond eq 'HASH') {
my %ret;
foreach my $key (keys %$cond) {
my $val = $cond->{$key};
if (ref $val) {
$self->throw("Can't handle this yet :(");
} else {
$ret{$self->_cond_key($attrs => $key)}
= $self->_cond_value($attrs => $key => $val);
}
}
return \%ret;
} else {
$self->throw("Can't handle this yet :(");
}
}
sub _cond_key {
my ($self, $attrs, $key) = @_;
my $action = $attrs->{_action} || '';
if ($action eq 'convert') {
unless ($key =~ s/^foreign\.//) {
$self->throw("Unable to convert relationship to WHERE clause: invalid key ${key}");
}
return $key;
} elsif ($action eq 'join') {
return $key unless $key =~ /\./;
my ($type, $field) = split(/\./, $key);
if (my $alias = $attrs->{_aliases}{$type}) {
my $class = $attrs->{_classes}{$alias};
$self->throw("Unknown column $field on $class as $alias")
unless exists $class->_columns->{$field};
return join('.', $alias, $field);
} else {
$self->throw( "Unable to resolve type ${type}: only have aliases for ".
join(', ', keys %{$attrs->{_aliases} || {}}) );
}
}
return $self->NEXT::ACTUAL::_cond_key($attrs, $key);
}
sub _cond_value {
my ($self, $attrs, $key, $value) = @_;
my $action = $attrs->{_action} || '';
if ($action eq 'convert') {
unless ($value =~ s/^self\.//) {
$self->throw( "Unable to convert relationship to WHERE clause: invalid value ${value}" );
}
unless ($self->_columns->{$value}) {
$self->throw( "Unable to convert relationship to WHERE clause: no such accessor ${value}" );
}
return $self->get_column($value);
} elsif ($action eq 'join') {
return $key unless $key =~ /\./;
my ($type, $field) = split(/\./, $value);
if (my $alias = $attrs->{_aliases}{$type}) {
my $class = $attrs->{_classes}{$alias};
$self->throw("Unknown column $field on $class as $alias")
unless exists $class->_columns->{$field};
return join('.', $alias, $field);
} else {
$self->throw( "Unable to resolve type ${type}: only have aliases for ".
join(', ', keys %{$attrs->{_aliases} || {}}) );
}
}
return $self->NEXT::ACTUAL::_cond_value($attrs, $key, $value)
}
=item search_related
My::Table->search_related('relname', $cond, $attrs);
=cut
sub search_related {
my $self = shift;
return $self->_query_related('search', @_);
}
=item count_related
My::Table->count_related('relname', $cond, $attrs);
=cut
sub count_related {
my $self = shift;
return $self->_query_related('count', @_);
}
sub _query_related {
my $self = shift;
my $meth = shift;
my $rel = shift;
my $attrs = { };
if (@_ > 1 && ref $_[$#_] eq 'HASH') {
$attrs = { %{ pop(@_) } };
}
my $rel_obj = $self->_relationships->{$rel};
$self->throw( "No such relationship ${rel}" ) unless $rel_obj;
$attrs = { %{$rel_obj->{attrs} || {}}, %{$attrs || {}} };
$self->throw( "Invalid query: @_" ) if (@_ > 1 && (@_ % 2 == 1));
my $query = ((@_ > 1) ? {@_} : shift);
$attrs->{_action} = 'convert'; # shouldn't we resolve the cond to something
# to merge into the AST really?
my ($cond) = $self->resolve_condition($rel_obj->{cond}, $attrs);
$query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
#use Data::Dumper; warn Dumper($query);
#warn $rel_obj->{class}." $meth $cond ".join(', ', @{$attrs->{bind}||[]});
delete $attrs->{_action};
return $self->resolve_class($rel_obj->{class}
)->$meth($query, $attrs);
}
=item create_related
My::Table->create_related('relname', \%col_data);
=cut
sub create_related {
my $class = shift;
return $class->new_related(@_)->insert;
}
=item new_related
My::Table->new_related('relname', \%col_data);
=cut
sub new_related {
my ($self, $rel, $values, $attrs) = @_;
$self->throw( "Can't call new_related as class method" )
unless ref $self;
$self->throw( "new_related needs a hash" )
unless (ref $values eq 'HASH');
my $rel_obj = $self->_relationships->{$rel};
$self->throw( "No such relationship ${rel}" ) unless $rel_obj;
$self->throw( "Can't abstract implicit create for ${rel}, condition not a hash" )
unless ref $rel_obj->{cond} eq 'HASH';
$attrs = { %{$rel_obj->{attrs}}, %{$attrs || {}}, _action => 'convert' };
my %fields = %{$self->resolve_condition($rel_obj->{cond},$attrs)};
$fields{$_} = $values->{$_} for keys %$values;
return $self->resolve_class($rel_obj->{class})->new(\%fields);
}
=item find_related
My::Table->find_related('relname', @pri_vals | \%pri_vals);
=cut
sub find_related {
my $self = shift;
my $rel = shift;
my $rel_obj = $self->_relationships->{$rel};
$self->throw( "No such relationship ${rel}" ) unless $rel_obj;
my ($cond) = $self->resolve_condition($rel_obj->{cond}, { _action => 'convert' });
$self->throw( "Invalid query: @_" ) if (@_ > 1 && (@_ % 2 == 1));
my $attrs = { };
if (@_ > 1 && ref $_[$#_] eq 'HASH') {
$attrs = { %{ pop(@_) } };
}
my $query = ((@_ > 1) ? {@_} : shift);
$query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
return $self->resolve_class($rel_obj->{class})->find($query);
}
=item find_or_create_related
My::Table->find_or_create_related('relname', \%col_data);
=cut
sub find_or_create_related {
my $self = shift;
return $self->find_related(@_) || $self->create_related(@_);
}
=item set_from_related
My::Table->set_from_related('relname', $rel_obj);
=cut
sub set_from_related {
my ($self, $rel, $f_obj) = @_;
my $rel_obj = $self->_relationships->{$rel};
$self->throw( "No such relationship ${rel}" ) unless $rel_obj;
my $cond = $rel_obj->{cond};
$self->throw( "set_from_related can only handle a hash condition; the "
."condition for $rel is of type ".(ref $cond ? ref $cond : 'plain scalar'))
unless ref $cond eq 'HASH';
my $f_class = $self->resolve_class($rel_obj->{class});
$self->throw( "Object $f_obj isn't a ".$f_class )
unless $f_obj->isa($f_class);
foreach my $key (keys %$cond) {
next if ref $cond->{$key}; # Skip literals and complex conditions
$self->throw("set_from_related can't handle $key as key")
unless $key =~ m/^foreign\.([^\.]+)$/;
my $val = $f_obj->get_column($1);
$self->throw("set_from_related can't handle ".$cond->{$key}." as value")
unless $cond->{$key} =~ m/^self\.([^\.]+)$/;
$self->set_column($1 => $val);
}
return 1;
}
=item update_from_related
My::Table->update_from_related('relname', $rel_obj);
=cut
sub update_from_related {
my $self = shift;
$self->set_from_related(@_);
$self->update;
}
=item delete_related
My::Table->delete_related('relname', $cond, $attrs);
=cut
sub delete_related {
my $self = shift;
return $self->search_related(@_)->delete;
}
1;
=back
=head1 AUTHORS
Matt S. Trout <mst@shadowcatsystems.co.uk>
=head1 LICENSE
You may distribute this code under the same terms as Perl itself.
=cut