=head1 SYNOPSIS
+ __PACKAGE__->add_relationship(
+ spiders => 'My::DB::Result::Creatures',
+ sub {
+ my $args = shift;
+ return {
+ "$args->{foreign_alias}.id" => { -ident => "$args->{self_alias}.id" },
+ "$args->{foreign_alias}.type" => 'arachnid'
+ };
+ },
+ );
+
=head1 DESCRIPTION
This class provides methods to describe the relationships between the
=over 4
-=item Arguments: 'relname', 'Foreign::Class', $cond, $attrs
+=item Arguments: 'relname', 'Foreign::Class', $condition, $attrs
=back
- __PACKAGE__->add_relationship('relname', 'Foreign::Class', $cond, $attrs);
+ __PACKAGE__->add_relationship('relname',
+ 'Foreign::Class',
+ $condition, $attrs);
+
+Create a custom relationship between one result source and another
+source, indicated by its class name.
=head3 condition
-The condition needs to be an L<SQL::Abstract>-style representation of the
-join between the tables. When resolving the condition for use in a C<JOIN>,
-keys using the pseudo-table C<foreign> are resolved to mean "the Table on the
-other side of the relationship", and values using the pseudo-table C<self>
-are resolved to mean "the Table this class is representing". Other
-restrictions, such as by value, sub-select and other tables, may also be
-used. Please check your database for C<JOIN> parameter support.
+The condition argument describes the C<ON> clause of the C<JOIN>
+expression used to connect the two sources when creating SQL queries.
+
+To create simple equality joins, supply a hashref containing the
+remote table column name as the key(s), and the local table column
+name as the value(s), for example given:
+
+ My::Schema::Author->has_many(
+ books => 'My::Schema::Book',
+ { 'foreign.author_id' => 'self.id' }
+ );
+
+A query like:
+
+ $author_rs->search_related('books')->next
+
+will result in the following C<JOIN> clause:
+
+ ... FROM author me LEFT JOIN book books ON books.author_id = me.id ...
+
+This describes a relationship between the C<Author> table and the
+C<Book> table where the C<Book> table has a column C<author_id>
+containing the ID value of the C<Author>.
+
+C<foreign> and C<self> are pseudo aliases and must be entered
+literally. They will be replaced with the actual correct table alias
+when the SQL is produced.
+
+Similarly:
+
+ My::Schema::Book->has_many(
+ editions => 'My::Schema::Edition',
+ {
+ 'foreign.publisher_id' => 'self.publisher_id',
+ 'foreign.type_id' => 'self.type_id',
+ }
+ );
+
+ ...
+
+ $book_rs->search_related('editions')->next
+
+will result in the C<JOIN> clause:
+
+ ... FROM book me
+ LEFT JOIN edition editions ON
+ editions.publisher_id = me.publisher_id
+ AND editions.type_id = me.type_id ...
+
+This describes the relationship from C<Book> to C<Edition>, where the
+C<Edition> table refers to a publisher and a type (e.g. "paperback"):
+
+As is the default in L<SQL::Abstract>, the key-value pairs will be
+C<AND>ed in the result. C<OR> can be achieved with an arrayref, for
+example a condition like:
-For example, if you're creating a relationship from C<Author> to C<Book>, where
-the C<Book> table has a column C<author_id> containing the ID of the C<Author>
-row:
+ My::Schema::Item->has_many(
+ related_item_links => My::Schema::Item::Links,
+ [
+ { 'foreign.left_itemid' => 'self.id' },
+ { 'foreign.right_itemid' => 'self.id' },
+ ],
+ );
- { 'foreign.author_id' => 'self.id' }
+will translate to the following C<JOIN> clause:
-will result in the C<JOIN> clause
+ ... FROM item me JOIN item_relations related_item_links ON
+ related_item_links.left_itemid = me.id
+ OR related_item_links.right_itemid = me.id ...
- author me JOIN book book ON book.author_id = me.id
+This describes the relationship from C<Item> to C<Item::Links>, where
+C<Item::Links> is a many-to-many linking table, linking items back to
+themselves in a peer fashion (without a "parent-child" designation)
-For multi-column foreign keys, you will need to specify a C<foreign>-to-C<self>
-mapping for each column in the key. For example, if you're creating a
-relationship from C<Book> to C<Edition>, where the C<Edition> table refers to a
-publisher and a type (e.g. "paperback"):
+To specify joins which describe more than a simple equality of column
+values, the custom join condition coderef syntax can be used. For
+example:
- {
- 'foreign.publisher_id' => 'self.publisher_id',
- 'foreign.type_id' => 'self.type_id',
+ My::Schema::Artist->has_many(
+ cds_80s => 'My::Schema::CD',
+ sub {
+ my $args = shift;
+
+ return {
+ "$args->{foreign_alias}.artist" => { -ident => "$args->{self_alias}.artistid" },
+ "$args->{foreign_alias}.year" => { '>', "1979", '<', "1990" },
+ };
+ }
+ );
+
+ ...
+
+ $artist_rs->search_related('cds_80s')->next;
+
+will result in the C<JOIN> clause:
+
+ ... FROM artist me LEFT JOIN cd cds_80s ON
+ cds_80s.artist = me.artistid
+ AND cds_80s.year < ?
+ AND cds_80s.year > ?
+
+with the bind values:
+
+ '1990', '1979'
+
+C<< $args->{foreign_alias} >> and C<< $args->{self_alias} >> are supplied the
+same values that would be otherwise substituted for C<foreign> and C<self>
+in the simple hashref syntax case.
+
+The coderef is expected to return a valid L<SQL::Abstract> query-structure, just
+like what one would supply as the first argument to
+L<DBIx::Class::ResultSet/search>. The return value will be passed directly to
+L<SQL::Abstract> and the resulting SQL will be used verbatim as the C<ON>
+clause of the C<JOIN> statement associated with this relationship.
+
+While every coderef-based condition must return a valid C<ON> clause, it may
+elect to additionally return a simplified join-free condition hashref when
+invoked as C<< $row_object->relationship >>, as opposed to
+C<< $rs->related_resultset('relationship') >>. In this case C<$row_object> is
+passed to the coderef as C<< $args->{self_rowobj} >>, so a user can do the
+following:
+
+ sub {
+ my $args = shift;
+
+ return (
+ {
+ "$args->{foreign_alias}.artist" => { -ident => "$args->{self_alias}.artistid" },
+ "$args->{foreign_alias}.year" => { '>', "1979", '<', "1990" },
+ },
+ $args->{self_rowobj} && {
+ "$args->{foreign_alias}.artist" => $args->{self_rowobj}->artistid,
+ "$args->{foreign_alias}.year" => { '>', "1979", '<', "1990" },
+ },
+ );
}
-This will result in the C<JOIN> clause:
+Now this code:
+
+ my $artist = $schema->resultset("Artist")->find({ id => 4 });
+ $artist->cds_80s->all;
+
+Can skip a C<JOIN> altogether and instead produce:
+
+ SELECT cds_80s.cdid, cds_80s.artist, cds_80s.title, cds_80s.year, cds_80s.genreid, cds_80s.single_track
+ FROM cd cds_80s
+ WHERE cds_80s.artist = ?
+ AND cds_80s.year < ?
+ AND cds_80s.year > ?
+
+With the bind values:
+
+ '4', '1990', '1979'
- book me JOIN edition edition ON edition.publisher_id = me.publisher_id
- AND edition.type_id = me.type_id
+Note that in order to be able to use
+L<< $row->create_related|DBIx::Class::Relationship::Base/create_related >>,
+the coderef must not only return as its second such a "simple" condition
+hashref which does not depend on joins being available, but the hashref must
+contain only plain values/deflatable objects, such that the result can be
+passed directly to L<DBIx::Class::Relationship::Base/set_from_related>. For
+instance the C<year> constraint in the above example prevents the relationship
+from being used to to create related objects (an exception will be thrown).
-Each key-value pair provided in a hashref will be used as C<AND>ed conditions.
-To add an C<OR>ed condition, use an arrayref of hashrefs. See the
-L<SQL::Abstract> documentation for more details.
+In order to allow the user to go truly crazy when generating a custom C<ON>
+clause, the C<$args> hashref passed to the subroutine contains some extra
+metadata. Currently the supplied coderef is executed as:
+
+ $relationship_info->{cond}->({
+ self_alias => The alias of the invoking resultset ('me' in case of a row object),
+ foreign_alias => The alias of the to-be-joined resultset (often matches relname),
+ self_resultsource => The invocant's resultsource,
+ foreign_relname => The relationship name (does *not* always match foreign_alias),
+ self_rowobj => The invocant itself in case of $row_obj->relationship
+ });
=head3 attributes
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
+=item proxy =E<gt> $column | \@columns | \%column
+
+The 'proxy' attribute can be used to retrieve values, and to perform
+updates if the relationship has 'cascade_update' set. The 'might_have'
+and 'has_one' relationships have this set by default; if you want a proxy
+to update across a 'belongs_to' relationship, you must set the attribute
+yourself.
+
+=over 4
+
+=item \@columns
An arrayref containing a list of accessors in the foreign class to create in
the main class. If, for example, you do the following:
- MyDB::Schema::CD->might_have(liner_notes => 'MyDB::Schema::LinerNotes',
+ MyApp::Schema::CD->might_have(liner_notes => 'MyApp::Schema::LinerNotes',
undef, {
proxy => [ qw/notes/ ],
});
-Then, assuming MyDB::Schema::LinerNotes has an accessor named notes, you can do:
+Then, assuming MyApp::Schema::LinerNotes has an accessor named notes, you can do:
- my $cd = MyDB::Schema::CD->find(1);
+ my $cd = MyApp::Schema::CD->find(1);
$cd->notes('Notes go here'); # set notes -- LinerNotes object is
# created if it doesn't exist
+For a 'belongs_to relationship, note the 'cascade_update':
+
+ MyApp::Schema::Track->belongs_to( cd => 'DBICTest::Schema::CD', 'cd,
+ { proxy => ['title'], cascade_update => 1 }
+ );
+ $track->title('New Title');
+ $track->update; # updates title in CD
+
+=item \%column
+
+A hashref where each key is the accessor you want installed in the main class,
+and its value is the name of the original in the fireign class.
+
+ MyApp::Schema::Track->belongs_to( cd => 'DBICTest::Schema::CD', 'cd', {
+ proxy => { cd_title => 'title' },
+ });
+
+This will create an accessor named C<cd_title> on the C<$track> row object.
+
+=back
+
+NOTE: you can pass a nested struct too, for example:
+
+ MyApp::Schema::Track->belongs_to( cd => 'DBICTest::Schema::CD', 'cd', {
+ proxy => [ 'year', { cd_title => 'title' } ],
+ });
+
=item accessor
Specifies the type of accessor that should be created for the relationship.
per-relationship basis by supplying C<< cascade_update => 0 >> in
the relationship attributes.
+The C<belongs_to> relationship does not update across relationships
+by default, so if you have a 'proxy' attribute on a belongs_to and want to
+use 'update' on it, you muse set C<< cascade_update => 1 >>.
+
This is not a RDMS style cascade update - it purely means that when
an object has update called on it, all the related objects also
have update called. It will not change foreign keys automatically -
# condition resolution may fail if an incomplete master-object prefetch
# is encountered - that is ok during prefetch construction (not yet in_storage)
- my $cond = try {
- $source->_resolve_condition( $rel_info->{cond}, $rel, $self )
+ my ($cond, $is_crosstable) = try {
+ $source->_resolve_condition( $rel_info->{cond}, $rel, $self, $rel )
}
catch {
if ($self->in_storage) {
$DBIx::Class::ResultSource::UNRESOLVABLE_CONDITION; # RV
};
- if ($cond eq $DBIx::Class::ResultSource::UNRESOLVABLE_CONDITION) {
- my $reverse = $source->reverse_relationship_info($rel);
- foreach my $rev_rel (keys %$reverse) {
- if ($reverse->{$rev_rel}{attrs}{accessor} && $reverse->{$rev_rel}{attrs}{accessor} eq 'multi') {
- $attrs->{related_objects}{$rev_rel} = [ $self ];
- weaken $attrs->{related_object}{$rev_rel}[0];
- } else {
- $attrs->{related_objects}{$rev_rel} = $self;
- weaken $attrs->{related_object}{$rev_rel};
+ # keep in mind that the following if() block is part of a do{} - no return()s!!!
+ if ($is_crosstable) {
+ $self->throw_exception (
+ "A cross-table relationship condition returned for statically declared '$rel'")
+ unless ref $rel_info->{cond} eq 'CODE';
+
+ # A WHOREIFFIC hack to reinvoke the entire condition resolution
+ # with the correct alias. Another way of doing this involves a
+ # lot of state passing around, and the @_ positions are already
+ # mapped out, making this crap a less icky option.
+ #
+ # The point of this exercise is to retain the spirit of the original
+ # $obj->search_related($rel) where the resulting rset will have the
+ # root alias as 'me', instead of $rel (as opposed to invoking
+ # $rs->search_related)
+
+ local $source->{_relationships}{me} = $source->{_relationships}{$rel}; # make the fake 'me' rel
+ my $obj_table_alias = lc($source->source_name) . '__row';
+ $obj_table_alias =~ s/\W+/_/g;
+
+ $source->resultset->search(
+ $self->ident_condition($obj_table_alias),
+ { alias => $obj_table_alias },
+ )->search_related('me', $query, $attrs)
+ }
+ else {
+ # FIXME - this conditional doesn't seem correct - got to figure out
+ # at some point what it does. Also the entire UNRESOLVABLE_CONDITION
+ # business seems shady - we could simply not query *at all*
+ if ($cond eq $DBIx::Class::ResultSource::UNRESOLVABLE_CONDITION) {
+ my $reverse = $source->reverse_relationship_info($rel);
+ foreach my $rev_rel (keys %$reverse) {
+ if ($reverse->{$rev_rel}{attrs}{accessor} && $reverse->{$rev_rel}{attrs}{accessor} eq 'multi') {
+ weaken($attrs->{related_objects}{$rev_rel}[0] = $self);
+ } else {
+ weaken($attrs->{related_objects}{$rev_rel} = $self);
+ }
}
}
- }
- if (ref $cond eq 'ARRAY') {
- $cond = [ map {
- if (ref $_ eq 'HASH') {
- my $hash;
- foreach my $key (keys %$_) {
- my $newkey = $key !~ /\./ ? "me.$key" : $key;
- $hash->{$newkey} = $_->{$key};
+ elsif (ref $cond eq 'ARRAY') {
+ $cond = [ map {
+ if (ref $_ eq 'HASH') {
+ my $hash;
+ foreach my $key (keys %$_) {
+ my $newkey = $key !~ /\./ ? "me.$key" : $key;
+ $hash->{$newkey} = $_->{$key};
+ }
+ $hash;
+ } else {
+ $_;
}
- $hash;
- } else {
- $_;
+ } @$cond ];
+ }
+ elsif (ref $cond eq 'HASH') {
+ foreach my $key (grep { ! /\./ } keys %$cond) {
+ $cond->{"me.$key"} = delete $cond->{$key};
}
- } @$cond ];
- } elsif (ref $cond eq 'HASH') {
- foreach my $key (grep { ! /\./ } keys %$cond) {
- $cond->{"me.$key"} = delete $cond->{$key};
}
+
+ $query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
+ $self->result_source->related_source($rel)->resultset->search(
+ $query, $attrs
+ );
}
- $query = ($query ? { '-and' => [ $cond, $query ] } : $cond);
- $self->result_source->related_source($rel)->resultset->search(
- $query, $attrs
- );
};
}
=cut
sub new_related {
- my ($self, $rel, $values, $attrs) = @_;
- return $self->search_related($rel)->new($values, $attrs);
+ my ($self, $rel, $values) = @_;
+
+ # FIXME - this is a bad position for this (also an identical copy in
+ # set_from_related), but I have no saner way to hook, and I absolutely
+ # want this to throw at least for coderefs, instead of the "insert a NULL
+ # when it gets hard" insanity --ribasushi
+ #
+ # sanity check - currently throw when a complex coderef rel is encountered
+ # FIXME - should THROW MOAR!
+
+ if (ref $self) { # cdbi calls this as a class method, /me vomits
+
+ my $rsrc = $self->result_source;
+ my (undef, $crosstable, $relcols) = $rsrc->_resolve_condition (
+ $rsrc->relationship_info($rel)->{cond}, $rel, $self, $rel
+ );
+
+ $self->throw_exception("Custom relationship '$rel' does not resolve to a join-free condition fragment")
+ if $crosstable;
+
+ if (@{$relcols || []} and @$relcols = grep { ! exists $values->{$_} } @$relcols) {
+ $self->throw_exception(sprintf (
+ "Custom relationship '%s' not definitive - returns conditions instead of values for column(s): %s",
+ $rel,
+ map { "'$_'" } @$relcols
+ ));
+ }
+ }
+
+ return $self->search_related($rel)->new_result($values);
}
=head2 create_related
sub create_related {
my $self = shift;
my $rel = shift;
- my $obj = $self->search_related($rel)->create(@_);
+ my $obj = $self->new_related($rel, @_)->insert;
delete $self->{related_resultsets}->{$rel};
return $obj;
}
sub set_from_related {
my ($self, $rel, $f_obj) = @_;
- my $rel_info = $self->relationship_info($rel);
- $self->throw_exception( "No such relationship ${rel}" ) unless $rel_info;
- my $cond = $rel_info->{cond};
- $self->throw_exception(
- "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 $rsrc = $self->result_source;
+ my $rel_info = $rsrc->relationship_info($rel)
+ or $self->throw_exception( "No such relationship ${rel}" );
+
if (defined $f_obj) {
my $f_class = $rel_info->{class};
$self->throw_exception( "Object $f_obj isn't a ".$f_class )
unless blessed $f_obj and $f_obj->isa($f_class);
}
- $self->set_columns(
- $self->result_source->_resolve_condition(
- $rel_info->{cond}, $f_obj, $rel));
+
+
+ # FIXME - this is a bad position for this (also an identical copy in
+ # new_related), but I have no saner way to hook, and I absolutely
+ # want this to throw at least for coderefs, instead of the "insert a NULL
+ # when it gets hard" insanity --ribasushi
+ #
+ # sanity check - currently throw when a complex coderef rel is encountered
+ # FIXME - should THROW MOAR!
+ my ($cond, $crosstable, $relcols) = $rsrc->_resolve_condition (
+ $rel_info->{cond}, $f_obj, $rel, $rel
+ );
+ $self->throw_exception("Custom relationship '$rel' does not resolve to a join-free condition fragment")
+ if $crosstable;
+ $self->throw_exception(sprintf (
+ "Custom relationship '%s' not definitive - returns conditions instead of values for column(s): %s",
+ $rel,
+ map { "'$_'" } @$relcols
+ )) if @{$relcols || []};
+
+ $self->set_columns($cond);
+
return 1;
}
the related object itself won't be deleted unless you call ->delete() on
it. This method just removes the link between the two objects.
-=head1 AUTHORS
+=head1 AUTHOR AND CONTRIBUTORS
-Matt S. Trout <mst@shadowcatsystems.co.uk>
+See L<AUTHOR|DBIx::Class/AUTHOR> and L<CONTRIBUTORS|DBIx::Class/CONTRIBUTORS> in DBIx::Class
=head1 LICENSE
projects / dbsrgits/DBIx-Class.git / blobdiff