use warnings;
use DBIx::Class::ResultSet;
-
-use Carp qw/croak/;
+use Carp::Clan qw/^DBIx::Class/;
+use Storable;
use base qw/DBIx::Class/;
__PACKAGE__->load_components(qw/AccessorGroup/);
-__PACKAGE__->mk_group_accessors('simple' =>
- qw/_ordered_columns _columns _primaries name resultset_class result_class schema from _relationships/);
+__PACKAGE__->mk_group_accessors('simple' => qw/_ordered_columns
+ _columns _primaries _unique_constraints name resultset_attributes
+ schema from _relationships column_info_from_storage/);
+
+__PACKAGE__->mk_group_accessors('component_class' => qw/resultset_class
+ result_class source_name/);
-=head1 NAME
+=head1 NAME
DBIx::Class::ResultSource - Result source object
=head1 METHODS
+=pod
+
+=head2 new
+
+ $class->new();
+
+ $class->new({attribute_name => value});
+
+Creates a new ResultSource object. Not normally called directly by end users.
+
=cut
sub new {
my ($class, $attrs) = @_;
$class = ref $class if ref $class;
- my $new = bless({ %{$attrs || {}} }, $class);
+ my $new = bless({ %{$attrs || {}}, _resultset => undef }, $class);
$new->{resultset_class} ||= 'DBIx::Class::ResultSet';
- $new->{_ordered_columns} ||= [];
- $new->{_columns} ||= {};
- $new->{_relationships} ||= {};
+ $new->{resultset_attributes} = { %{$new->{resultset_attributes} || {}} };
+ $new->{_ordered_columns} = [ @{$new->{_ordered_columns}||[]}];
+ $new->{_columns} = { %{$new->{_columns}||{}} };
+ $new->{_relationships} = { %{$new->{_relationships}||{}} };
$new->{name} ||= "!!NAME NOT SET!!";
+ $new->{_columns_info_loaded} ||= 0;
return $new;
}
-sub add_columns {
- my ($self, @cols) = @_;
- $self->_ordered_columns( \@cols )
- if !$self->_ordered_columns;
- push @{ $self->_ordered_columns }, @cols;
- while (my $col = shift @cols) {
-
- my $column_info = ref $cols[0] ? shift : {};
- # If next entry is { ... } use that for the column info, if not
- # use an empty hashref
-
- $self->_columns->{$col} = $column_info;
- }
-}
-
-*add_column = \&add_columns;
+=pod
=head2 add_columns
$table->add_columns('col1' => \%col1_info, 'col2' => \%col2_info, ...);
-Adds columns to the result source. If supplied key => hashref pairs uses
-the hashref as the column_info for that column.
+Adds columns to the result source. If supplied key => hashref pairs, uses
+the hashref as the column_info for that column. Repeated calls of this
+method will add more columns, not replace them.
+
+The contents of the column_info are not set in stone. The following
+keys are currently recognised/used by DBIx::Class:
+
+=over 4
+
+=item accessor
+
+Use this to set the name of the accessor for this column. If unset,
+the name of the column will be used.
+
+=item data_type
+
+This contains the column type. It is automatically filled by the
+L<SQL::Translator::Producer::DBIx::Class::File> producer, and the
+L<DBIx::Class::Schema::Loader> module. If you do not enter a
+data_type, DBIx::Class will attempt to retrieve it from the
+database for you, using L<DBI>'s column_info method. The values of this
+key are typically upper-cased.
+
+Currently there is no standard set of values for the data_type. Use
+whatever your database supports.
+
+=item size
+
+The length of your column, if it is a column type that can have a size
+restriction. This is currently not used by DBIx::Class.
+
+=item is_nullable
+
+Set this to a true value for a columns that is allowed to contain
+NULL values. This is currently not used by DBIx::Class.
+
+=item is_auto_increment
+
+Set this to a true value for a column whose value is somehow
+automatically set. This is used to determine which columns to empty
+when cloning objects using C<copy>.
+
+=item is_foreign_key
+
+Set this to a true value for a column that contains a key from a
+foreign table. This is currently not used by DBIx::Class.
+
+=item default_value
+
+Set this to the default value which will be inserted into a column
+by the database. Can contain either a value or a function. This is
+currently not used by DBIx::Class.
+
+=item sequence
+
+Set this on a primary key column to the name of the sequence used to
+generate a new key value. If not specified, L<DBIx::Class::PK::Auto>
+will attempt to retrieve the name of the sequence from the database
+automatically.
+
+=back
=head2 add_column
$table->add_column('col' => \%info?);
-Convenience alias to add_columns
+Convenience alias to add_columns.
=cut
-sub resultset {
- my $self = shift;
- return $self->resultset_class->new($self);
+sub add_columns {
+ my ($self, @cols) = @_;
+ $self->_ordered_columns(\@cols) unless $self->_ordered_columns;
+
+ my @added;
+ my $columns = $self->_columns;
+ while (my $col = shift @cols) {
+ # If next entry is { ... } use that for the column info, if not
+ # use an empty hashref
+ my $column_info = ref $cols[0] ? shift(@cols) : {};
+ push(@added, $col) unless exists $columns->{$col};
+ $columns->{$col} = $column_info;
+ }
+ push @{ $self->_ordered_columns }, @added;
+ return $self;
}
-=head2 has_column
-
- if ($obj->has_column($col)) { ... }
-
-Returns 1 if the source has a column of this name, 0 otherwise.
-
-=cut
+*add_column = \&add_columns;
+
+=head2 has_column
+
+ if ($obj->has_column($col)) { ... }
+
+Returns true if the source has a column of this name, false otherwise.
+
+=cut
sub has_column {
my ($self, $column) = @_;
return exists $self->_columns->{$column};
}
-=head2 column_info
+=head2 column_info
- my $info = $obj->column_info($col);
+ my $info = $obj->column_info($col);
-Returns the column metadata hashref for a column.
-
-=cut
+Returns the column metadata hashref for a column. See the description
+of add_column for information on the contents of the hashref.
+
+=cut
sub column_info {
my ($self, $column) = @_;
- croak "No such column $column" unless exists $self->_columns->{$column};
+ $self->throw_exception("No such column $column")
+ unless exists $self->_columns->{$column};
+ #warn $self->{_columns_info_loaded}, "\n";
+ if ( ! $self->_columns->{$column}{data_type}
+ and $self->column_info_from_storage
+ and ! $self->{_columns_info_loaded}
+ and $self->schema and $self->storage )
+ {
+ $self->{_columns_info_loaded}++;
+ my $info;
+ my $lc_info;
+ # eval for the case of storage without table
+ eval { $info = $self->storage->columns_info_for( $self->from, keys %{$self->_columns} ) };
+ unless ($@) {
+ for my $realcol ( keys %{$info} ) {
+ $lc_info->{lc $realcol} = $info->{$realcol};
+ }
+ foreach my $col ( keys %{$self->_columns} ) {
+ $self->_columns->{$col} = { %{ $self->_columns->{$col}}, %{$info->{$col} || $lc_info->{lc $col}} };
+ }
+ }
+ }
return $self->_columns->{$column};
}
+=head2 load_column_info_from_storage
+
+Enables the on-demand automatic loading of the above column
+metadata from storage as neccesary.
+
+=cut
+
+sub load_column_info_from_storage { shift->column_info_from_storage(1) }
+
=head2 columns
- my @column_names = $obj->columns;
-
-=cut
+ my @column_names = $obj->columns;
+
+Returns all column names in the order they were declared to add_columns.
+
+=cut
sub columns {
- croak "columns() is a read-only accessor, did you mean add_columns()?" if (@_ > 1);
- return keys %{shift->_columns};
+ my $self = shift;
+ $self->throw_exception(
+ "columns() is a read-only accessor, did you mean add_columns()?"
+ ) if (@_ > 1);
+ return @{$self->{_ordered_columns}||[]};
}
-=head2 ordered_columns
+=head2 remove_columns
+
+ $table->remove_columns(qw/col1 col2 col3/);
+
+Removes columns from the result source.
+
+=head2 remove_column
- my @column_names = $obj->ordered_columns;
+ $table->remove_column('col');
-Like columns(), but returns column names using the order in which they were
-originally supplied to add_columns().
+Convenience alias to remove_columns.
=cut
-sub ordered_columns {
- return @{shift->{_ordered_columns}||[]};
+sub remove_columns {
+ my ($self, @cols) = @_;
+
+ return unless $self->_ordered_columns;
+
+ my $columns = $self->_columns;
+ my @remaining;
+
+ foreach my $col (@{$self->_ordered_columns}) {
+ push @remaining, $col unless grep(/$col/, @cols);
+ }
+
+ foreach (@cols) {
+ undef $columns->{$_};
+ };
+
+ $self->_ordered_columns(\@remaining);
}
-=head2 set_primary_key(@cols)
-
+*remove_column = \&remove_columns;
+
+=head2 set_primary_key
+
+=over 4
+
+=item Arguments: @cols
+
+=back
+
Defines one or more columns as primary key for this source. Should be
called after C<add_columns>.
-
-=cut
+
+Additionally, defines a unique constraint named C<primary>.
+
+The primary key columns are used by L<DBIx::Class::PK::Auto> to
+retrieve automatically created values from the database.
+
+=cut
sub set_primary_key {
my ($self, @cols) = @_;
# check if primary key columns are valid columns
- for (@cols) {
- $self->throw("No such column $_ on table ".$self->name)
- unless $self->has_column($_);
+ foreach my $col (@cols) {
+ $self->throw_exception("No such column $col on table " . $self->name)
+ unless $self->has_column($col);
}
$self->_primaries(\@cols);
+
+ $self->add_unique_constraint(primary => \@cols);
}
-=head2 primary_columns
-
+=head2 primary_columns
+
Read-only accessor which returns the list of primary keys.
-
-=cut
+
+=cut
sub primary_columns {
return @{shift->_primaries||[]};
}
+=head2 add_unique_constraint
+
+Declare a unique constraint on this source. Call once for each unique
+constraint.
+
+ # For UNIQUE (column1, column2)
+ __PACKAGE__->add_unique_constraint(
+ constraint_name => [ qw/column1 column2/ ],
+ );
+
+Alternatively, you can specify only the columns:
+
+ __PACKAGE__->add_unique_constraint([ qw/column1 column2/ ]);
+
+This will result in a unique constraint named C<table_column1_column2>, where
+C<table> is replaced with the table name.
+
+Unique constraints are used, for example, when you call
+L<DBIx::Class::ResultSet/find>. Only columns in the constraint are searched.
+
+=cut
+
+sub add_unique_constraint {
+ my $self = shift;
+ my $cols = pop @_;
+ my $name = shift;
+
+ $name ||= $self->name_unique_constraint($cols);
+
+ foreach my $col (@$cols) {
+ $self->throw_exception("No such column $col on table " . $self->name)
+ unless $self->has_column($col);
+ }
+
+ my %unique_constraints = $self->unique_constraints;
+ $unique_constraints{$name} = $cols;
+ $self->_unique_constraints(\%unique_constraints);
+}
+
+=head2 name_unique_constraint
+
+Return a name for a unique constraint containing the specified columns. These
+names consist of the table name and each column name, separated by underscores.
+
+For example, a constraint on a table named C<cd> containing the columns
+C<artist> and C<title> would result in a constraint name of C<cd_artist_title>.
+
+=cut
+
+sub name_unique_constraint {
+ my ($self, $cols) = @_;
+
+ return join '_', $self->name, @$cols;
+}
+
+=head2 unique_constraints
+
+Read-only accessor which returns the list of unique constraints on this source.
+
+=cut
+
+sub unique_constraints {
+ return %{shift->_unique_constraints||{}};
+}
+
+=head2 unique_constraint_names
+
+Returns the list of unique constraint names defined on this source.
+
+=cut
+
+sub unique_constraint_names {
+ my ($self) = @_;
+
+ my %unique_constraints = $self->unique_constraints;
+
+ return keys %unique_constraints;
+}
+
+=head2 unique_constraint_columns
+
+Returns the list of columns that make up the specified unique constraint.
+
+=cut
+
+sub unique_constraint_columns {
+ my ($self, $constraint_name) = @_;
+
+ my %unique_constraints = $self->unique_constraints;
+
+ $self->throw_exception(
+ "Unknown unique constraint $constraint_name on '" . $self->name . "'"
+ ) unless exists $unique_constraints{$constraint_name};
+
+ return @{ $unique_constraints{$constraint_name} };
+}
+
=head2 from
Returns an expression of the source to be supplied to storage to specify
-retrieval from this source; in the case of a database the required FROM clause
-contents.
+retrieval from this source. In the case of a database, the required FROM
+clause contents.
-=cut
+=head2 schema
+
+Returns the L<DBIx::Class::Schema> object that this result source
+belongs too.
=head2 storage
-Returns the storage handle for the current schema
+Returns the storage handle for the current schema.
+
+See also: L<DBIx::Class::Storage>
=cut
$source->add_relationship('relname', 'related_source', $cond, $attrs);
-The relation name can be arbitrary, but must be unique for each relationship
-attached to this result source. 'related_source' should be the name with
-which the related result source was registered with the current schema
-(for simple schemas this is usally either Some::Namespace::Foo or just Foo)
+The relationship name can be arbitrary, but must be unique for each
+relationship attached to this result source. 'related_source' should
+be the name with which the related result source was registered with
+the current schema. For example:
+
+ $schema->source('Book')->add_relationship('reviews', 'Review', {
+ 'foreign.book_id' => 'self.id',
+ });
+
+The condition C<$cond> needs to be an L<SQL::Abstract>-style
+representation of the join between the tables. For example, if you're
+creating a rel from Author to Book,
+
+ { 'foreign.author_id' => 'self.id' }
-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,
+will result in the JOIN clause
+
+ author me JOIN book foreign ON foreign.author_id = me.id
- { 'foreign.foo_id' => 'self.id' }
-
-will result in the JOIN clause
-
- foo me JOIN bar bar ON bar.foo_id = me.id
-
You can specify as many foreign => self mappings as necessary.
-Valid attributes are as follows:
-
-=over 4
-
-=item join_type
-
-Explicitly specifies the type of join to use in the relationship. Any SQL
-join type is valid, e.g. C<LEFT> or C<RIGHT>. It will be placed in the SQL
-command immediately before C<JOIN>.
-
-=item proxy
-
-An arrayref containing a list of accessors in the foreign class to proxy in
-the main class. If, for example, you do the following:
-
- __PACKAGE__->might_have(bar => 'Bar', undef, { proxy => qw[/ margle /] });
-
-Then, assuming Bar has an accessor named margle, you can do:
-
- my $obj = Foo->find(1);
- $obj->margle(10); # set margle; Bar object is created if it doesn't exist
-
-=item accessor
-
-Specifies the type of accessor that should be created for the relationship.
-Valid values are C<single> (for when there is only a single related object),
-C<multi> (when there can be many), and C<filter> (for when there is a single
-related object, but you also want the relationship accessor to double as
-a column accessor). For C<multi> accessors, an add_to_* method is also
-created, which calls C<create_related> for the relationship.
-
+Valid attributes are as follows:
+
+=over 4
+
+=item join_type
+
+Explicitly specifies the type of join to use in the relationship. Any
+SQL join type is valid, e.g. C<LEFT> or C<RIGHT>. It will be placed in
+the SQL command immediately before C<JOIN>.
+
+=item proxy
+
+An arrayref containing a list of accessors in the foreign class to proxy in
+the main class. If, for example, you do the following:
+
+ CD->might_have(liner_notes => 'LinerNotes', undef, {
+ proxy => [ qw/notes/ ],
+ });
+
+Then, assuming LinerNotes has an accessor named notes, you can do:
+
+ my $cd = CD->find(1);
+ # set notes -- LinerNotes object is created if it doesn't exist
+ $cd->notes('Notes go here');
+
+=item accessor
+
+Specifies the type of accessor that should be created for the
+relationship. Valid values are C<single> (for when there is only a single
+related object), C<multi> (when there can be many), and C<filter> (for
+when there is a single related object, but you also want the relationship
+accessor to double as a column accessor). For C<multi> accessors, an
+add_to_* method is also created, which calls C<create_related> for the
+relationship.
+
=back
=cut
sub add_relationship {
my ($self, $rel, $f_source_name, $cond, $attrs) = @_;
- die "Can't create relationship without join condition" unless $cond;
+ $self->throw_exception("Can't create relationship without join condition")
+ unless $cond;
$attrs ||= {};
+
my %rels = %{ $self->_relationships };
$rels{$rel} = { class => $f_source_name,
+ source => $f_source_name,
cond => $cond,
attrs => $attrs };
$self->_relationships(\%rels);
+ return $self;
+
+ # XXX disabled. doesn't work properly currently. skip in tests.
+
my $f_source = $self->schema->source($f_source_name);
unless ($f_source) {
- eval "require $f_source_name;";
- if ($@) {
- die $@ unless $@ =~ /Can't locate/;
- }
+ $self->ensure_class_loaded($f_source_name);
$f_source = $f_source_name->result_source;
+ #my $s_class = ref($self->schema);
+ #$f_source_name =~ m/^${s_class}::(.*)$/;
+ #$self->schema->register_class(($1 || $f_source_name), $f_source_name);
+ #$f_source = $self->schema->source($f_source_name);
}
return unless $f_source; # Can't test rel without f_source
eval { $self->resolve_join($rel, 'me') };
if ($@) { # If the resolve failed, back out and re-throw the error
- delete $rels{$rel}; #
+ delete $rels{$rel}; #
$self->_relationships(\%rels);
- die "Error creating relationship $rel: $@";
+ $self->throw_exception("Error creating relationship $rel: $@");
}
1;
}
-=head2 relationships()
+=head2 relationships
-Returns all valid relationship names for this source
+Returns all relationship names for this source.
=cut
return keys %{shift->_relationships};
}
-=head2 relationship_info($relname)
+=head2 relationship_info
+
+=over 4
-Returns the relationship information for the specified relationship name
+=item Arguments: $relname
+
+=back
+
+Returns a hash of relationship information for the specified relationship
+name.
=cut
sub relationship_info {
my ($self, $rel) = @_;
return $self->_relationships->{$rel};
-}
+}
+
+=head2 has_relationship
+
+=over 4
+
+=item Arguments: $rel
+
+=back
+
+Returns true if the source has a relationship of this name, false otherwise.
+
+=cut
+
+sub has_relationship {
+ my ($self, $rel) = @_;
+ return exists $self->_relationships->{$rel};
+}
+
+=head2 reverse_relationship_info
-=head2 resolve_join($relation)
+=over 4
-Returns the join structure required for the related result source
+=item Arguments: $relname
+
+=back
+
+Returns an array of hash references of relationship information for
+the other side of the specified relationship name.
+
+=cut
+
+sub reverse_relationship_info {
+ my ($self, $rel) = @_;
+ my $rel_info = $self->relationship_info($rel);
+ my $ret = {};
+
+ return $ret unless ((ref $rel_info->{cond}) eq 'HASH');
+
+ my @cond = keys(%{$rel_info->{cond}});
+ my @refkeys = map {/^\w+\.(\w+)$/} @cond;
+ my @keys = map {$rel_info->{cond}->{$_} =~ /^\w+\.(\w+)$/} @cond;
+
+ # Get the related result source for this relationship
+ my $othertable = $self->related_source($rel);
+
+ # Get all the relationships for that source that related to this source
+ # whose foreign column set are our self columns on $rel and whose self
+ # columns are our foreign columns on $rel.
+ my @otherrels = $othertable->relationships();
+ my $otherrelationship;
+ foreach my $otherrel (@otherrels) {
+ my $otherrel_info = $othertable->relationship_info($otherrel);
+
+ my $back = $othertable->related_source($otherrel);
+ next unless $back->name eq $self->name;
+
+ my @othertestconds;
+
+ if (ref $otherrel_info->{cond} eq 'HASH') {
+ @othertestconds = ($otherrel_info->{cond});
+ }
+ elsif (ref $otherrel_info->{cond} eq 'ARRAY') {
+ @othertestconds = @{$otherrel_info->{cond}};
+ }
+ else {
+ next;
+ }
+
+ foreach my $othercond (@othertestconds) {
+ my @other_cond = keys(%$othercond);
+ my @other_refkeys = map {/^\w+\.(\w+)$/} @other_cond;
+ my @other_keys = map {$othercond->{$_} =~ /^\w+\.(\w+)$/} @other_cond;
+ next if (!$self->compare_relationship_keys(\@refkeys, \@other_keys) ||
+ !$self->compare_relationship_keys(\@other_refkeys, \@keys));
+ $ret->{$otherrel} = $otherrel_info;
+ }
+ }
+ return $ret;
+}
+
+=head2 compare_relationship_keys
+
+=over 4
+
+=item Arguments: $keys1, $keys2
+
+=back
+
+Returns true if both sets of keynames are the same, false otherwise.
+
+=cut
+
+sub compare_relationship_keys {
+ my ($self, $keys1, $keys2) = @_;
+
+ # Make sure every keys1 is in keys2
+ my $found;
+ foreach my $key (@$keys1) {
+ $found = 0;
+ foreach my $prim (@$keys2) {
+ if ($prim eq $key) {
+ $found = 1;
+ last;
+ }
+ }
+ last unless $found;
+ }
+
+ # Make sure every key2 is in key1
+ if ($found) {
+ foreach my $prim (@$keys2) {
+ $found = 0;
+ foreach my $key (@$keys1) {
+ if ($prim eq $key) {
+ $found = 1;
+ last;
+ }
+ }
+ last unless $found;
+ }
+ }
+
+ return $found;
+}
+
+=head2 resolve_join
+
+=over 4
+
+=item Arguments: $relation
+
+=back
+
+Returns the join structure required for the related result source.
=cut
sub resolve_join {
- shift->result_class->_resolve_join(@_);
+ my ($self, $join, $alias, $seen) = @_;
+ $seen ||= {};
+ if (ref $join eq 'ARRAY') {
+ return map { $self->resolve_join($_, $alias, $seen) } @$join;
+ } elsif (ref $join eq 'HASH') {
+ return
+ map {
+ my $as = ($seen->{$_} ? $_.'_'.($seen->{$_}+1) : $_);
+ ($self->resolve_join($_, $alias, $seen),
+ $self->related_source($_)->resolve_join($join->{$_}, $as, $seen));
+ } keys %$join;
+ } elsif (ref $join) {
+ $self->throw_exception("No idea how to resolve join reftype ".ref $join);
+ } else {
+ my $count = ++$seen->{$join};
+ #use Data::Dumper; warn Dumper($seen);
+ my $as = ($count > 1 ? "${join}_${count}" : $join);
+ my $rel_info = $self->relationship_info($join);
+ $self->throw_exception("No such relationship ${join}") unless $rel_info;
+ my $type = $rel_info->{attrs}{join_type} || '';
+ return [ { $as => $self->related_source($join)->from,
+ -join_type => $type },
+ $self->resolve_condition($rel_info->{cond}, $as, $alias) ];
+ }
}
-1;
+=head2 resolve_condition
+
+=over 4
+
+=item Arguments: $cond, $as, $alias|$object
+
+=back
+
+Resolves the passed condition to a concrete query fragment. If given an alias,
+returns a join condition; if given an object, inverts that object to produce
+a related conditional from that object.
+
+=cut
+
+sub resolve_condition {
+ my ($self, $cond, $as, $for) = @_;
+ #warn %$cond;
+ if (ref $cond eq 'HASH') {
+ my %ret;
+ foreach my $k (keys %{$cond}) {
+ my $v = $cond->{$k};
+ # XXX should probably check these are valid columns
+ $k =~ s/^foreign\.// ||
+ $self->throw_exception("Invalid rel cond key ${k}");
+ $v =~ s/^self\.// ||
+ $self->throw_exception("Invalid rel cond val ${v}");
+ if (ref $for) { # Object
+ #warn "$self $k $for $v";
+ $ret{$k} = $for->get_column($v);
+ #warn %ret;
+ } elsif (!defined $for) { # undef, i.e. "no object"
+ $ret{$k} = undef;
+ } elsif (ref $as) { # reverse object
+ $ret{$v} = $as->get_column($k);
+ } elsif (!defined $as) { # undef, i.e. "no reverse object"
+ $ret{$v} = undef;
+ } else {
+ $ret{"${as}.${k}"} = "${for}.${v}";
+ }
+ }
+ return \%ret;
+ } elsif (ref $cond eq 'ARRAY') {
+ return [ map { $self->resolve_condition($_, $as, $for) } @$cond ];
+ } else {
+ die("Can't handle this yet :(");
+ }
+}
+
+=head2 resolve_prefetch
+
+=over 4
+
+=item Arguments: hashref/arrayref/scalar
+
+=back
+
+Accepts one or more relationships for the current source and returns an
+array of column names for each of those relationships. Column names are
+prefixed relative to the current source, in accordance with where they appear
+in the supplied relationships. Examples:
+
+ my $source = $schema->resultset('Tag')->source;
+ @columns = $source->resolve_prefetch( { cd => 'artist' } );
+
+ # @columns =
+ #(
+ # 'cd.cdid',
+ # 'cd.artist',
+ # 'cd.title',
+ # 'cd.year',
+ # 'cd.artist.artistid',
+ # 'cd.artist.name'
+ #)
+
+ @columns = $source->resolve_prefetch( qw[/ cd /] );
+
+ # @columns =
+ #(
+ # 'cd.cdid',
+ # 'cd.artist',
+ # 'cd.title',
+ # 'cd.year'
+ #)
+
+ $source = $schema->resultset('CD')->source;
+ @columns = $source->resolve_prefetch( qw[/ artist producer /] );
+
+ # @columns =
+ #(
+ # 'artist.artistid',
+ # 'artist.name',
+ # 'producer.producerid',
+ # 'producer.name'
+ #)
+
+=cut
+
+sub resolve_prefetch {
+ my ($self, $pre, $alias, $seen, $order, $collapse) = @_;
+ $seen ||= {};
+ #$alias ||= $self->name;
+ #warn $alias, Dumper $pre;
+ if( ref $pre eq 'ARRAY' ) {
+ return
+ map { $self->resolve_prefetch( $_, $alias, $seen, $order, $collapse ) }
+ @$pre;
+ }
+ elsif( ref $pre eq 'HASH' ) {
+ my @ret =
+ map {
+ $self->resolve_prefetch($_, $alias, $seen, $order, $collapse),
+ $self->related_source($_)->resolve_prefetch(
+ $pre->{$_}, "${alias}.$_", $seen, $order, $collapse)
+ } keys %$pre;
+ #die Dumper \@ret;
+ return @ret;
+ }
+ elsif( ref $pre ) {
+ $self->throw_exception(
+ "don't know how to resolve prefetch reftype ".ref($pre));
+ }
+ else {
+ my $count = ++$seen->{$pre};
+ my $as = ($count > 1 ? "${pre}_${count}" : $pre);
+ my $rel_info = $self->relationship_info( $pre );
+ $self->throw_exception( $self->name . " has no such relationship '$pre'" )
+ unless $rel_info;
+ my $as_prefix = ($alias =~ /^.*?\.(.+)$/ ? $1.'.' : '');
+ my $rel_source = $self->related_source($pre);
+
+ if (exists $rel_info->{attrs}{accessor}
+ && $rel_info->{attrs}{accessor} eq 'multi') {
+ $self->throw_exception(
+ "Can't prefetch has_many ${pre} (join cond too complex)")
+ unless ref($rel_info->{cond}) eq 'HASH';
+ my @key = map { (/^foreign\.(.+)$/ ? ($1) : ()); }
+ keys %{$rel_info->{cond}};
+ $collapse->{"${as_prefix}${pre}"} = \@key;
+ my @ord = (ref($rel_info->{attrs}{order_by}) eq 'ARRAY'
+ ? @{$rel_info->{attrs}{order_by}}
+ : (defined $rel_info->{attrs}{order_by}
+ ? ($rel_info->{attrs}{order_by})
+ : ()));
+ push(@$order, map { "${as}.$_" } (@key, @ord));
+ }
+
+ return map { [ "${as}.$_", "${as_prefix}${pre}.$_", ] }
+ $rel_source->columns;
+ #warn $alias, Dumper (\@ret);
+ #return @ret;
+ }
+}
+
+=head2 related_source
+
+=over 4
+
+=item Arguments: $relname
+
+=back
+
+Returns the result source object for the given relationship.
+
+=cut
+
+sub related_source {
+ my ($self, $rel) = @_;
+ if( !$self->has_relationship( $rel ) ) {
+ $self->throw_exception("No such relationship '$rel'");
+ }
+ return $self->schema->source($self->relationship_info($rel)->{source});
+}
+
+=head2 related_class
+
+=over 4
+
+=item Arguments: $relname
+
+=back
+
+Returns the class name for objects in the given relationship.
+
+=cut
+
+sub related_class {
+ my ($self, $rel) = @_;
+ if( !$self->has_relationship( $rel ) ) {
+ $self->throw_exception("No such relationship '$rel'");
+ }
+ return $self->schema->class($self->relationship_info($rel)->{source});
+}
+
+=head2 resultset
+
+Returns a resultset for the given source. This will initially be created
+on demand by calling
+
+ $self->resultset_class->new($self, $self->resultset_attributes)
+
+but is cached from then on unless resultset_class changes.
+
+=head2 resultset_class
+
+Set the class of the resultset, this is useful if you want to create your
+own resultset methods. Create your own class derived from
+L<DBIx::Class::ResultSet>, and set it here.
+
+=head2 resultset_attributes
+
+Specify here any attributes you wish to pass to your specialised resultset.
+
+=cut
+
+sub resultset {
+ my $self = shift;
+ $self->throw_exception(
+ 'resultset does not take any arguments. If you want another resultset, '.
+ 'call it on the schema instead.'
+ ) if scalar @_;
+
+ # disabled until we can figure out a way to do it without consistency issues
+ #
+ #return $self->{_resultset}
+ # if ref $self->{_resultset} eq $self->resultset_class;
+ #return $self->{_resultset} =
+
+ return $self->resultset_class->new(
+ $self, $self->{resultset_attributes}
+ );
+}
+
+=head2 source_name
+
+=over 4
+
+=item Arguments: $source_name
+
+=back
+
+Set the name of the result source when it is loaded into a schema.
+This is usefull if you want to refer to a result source by a name other than
+its class name.
+
+ package ArchivedBooks;
+ use base qw/DBIx::Class/;
+ __PACKAGE__->table('books_archive');
+ __PACKAGE__->source_name('Books');
+
+ # from your schema...
+ $schema->resultset('Books')->find(1);
+
+=head2 throw_exception
+
+See L<DBIx::Class::Schema/"throw_exception">.
+
+=cut
+
+sub throw_exception {
+ my $self = shift;
+ if (defined $self->schema) {
+ $self->schema->throw_exception(@_);
+ } else {
+ croak(@_);
+ }
+}
=head1 AUTHORS