position INTEGER NOT NULL
);
-Optionally, add one or more columns to specify groupings, allowing you
+Optionally, add one or more columns to specify groupings, allowing you
to maintain independent ordered lists within one table:
CREATE TABLE items (
other_group_id INTEGER NOT NULL
);
-In your Schema or DB class add "Ordered" to the top
+In your Schema or DB class add "Ordered" to the top
of the component list.
__PACKAGE__->load_components(qw( Ordered ... ));
-Specify the column that stores the position number for
+Specify the column that stores the position number for
each row.
package My::Item;
=head1 DESCRIPTION
-This module provides a simple interface for modifying the ordered
+This module provides a simple interface for modifying the ordered
position of DBIx::Class objects.
=head1 AUTO UPDATE
-All of the move_* methods automatically update the rows involved in
-the query. This is not configurable and is due to the fact that if you
+All of the move_* methods automatically update the rows involved in
+the query. This is not configurable and is due to the fact that if you
move a record it always causes other records in the list to be updated.
=head1 METHODS
__PACKAGE__->position_column('position');
-Sets and retrieves the name of the column that stores the
+Sets and retrieves the name of the column that stores the
positional value of each record. Defaults to "position".
=cut
__PACKAGE__->grouping_column('group_id');
-This method specifies a column to limit all queries in
-this module by. This effectively allows you to have multiple
+This method specifies a column to limit all queries in
+this module by. This effectively allows you to have multiple
ordered lists within the same table.
=cut
my $sibling = $item->first_sibling();
-Returns the first sibling object, or 0 if the first sibling
+Returns the first sibling object, or 0 if the first sibling
is this sibling.
=cut
my $sibling = $item->last_sibling();
-Returns the last sibling, or 0 if the last sibling is this
+Returns the last sibling, or 0 if the last sibling is this
sibling.
=cut
return defined $lsib ? $lsib : 0;
}
-# an optimized method to get the last sibling position value without inflating a row object
+# an optimized method to get the last sibling position value without inflating a result object
sub _last_sibling_posval {
my $self = shift;
my $position_column = $self->position_column;
my $position_column = $self->position_column;
- if ($self->is_column_changed ($position_column) ) {
+ my $is_txn;
+ if ($is_txn = $self->result_source->schema->storage->transaction_depth) {
+ # Reload position state from storage
+ # The thinking here is that if we are in a transaction, it is
+ # *more likely* the object went out of sync due to resultset
+ # level shenanigans. Instead of always reloading (slow) - go
+ # ahead and hand-hold only in the case of higher layers
+ # requesting the safety of a txn
+
+ $self->store_column(
+ $position_column,
+ ( $self->result_source
+ ->resultset
+ ->search($self->_storage_ident_condition, { rows => 1, columns => $position_column })
+ ->cursor
+ ->next
+ )[0] || $self->throw_exception(
+ sprintf "Unable to locate object '%s' in storage - object went ouf of sync...?",
+ $self->ID
+ ),
+ );
+ delete $self->{_dirty_columns}{$position_column};
+ }
+ elsif ($self->is_column_changed ($position_column) ) {
# something changed our position, we need to know where we
# used to be - use the stashed value
$self->store_column($position_column, delete $self->{_column_data_in_storage}{$position_column});
return 0;
}
- my $guard = $self->result_source->schema->txn_scope_guard;
+ my $guard = $is_txn ? undef : $self->result_source->schema->txn_scope_guard;
my ($direction, @between);
if ( $from_position < $to_position ) {
$self->_shift_siblings ($direction, @between);
$self->_ordered_internal_update({ $position_column => $new_pos_val });
- $guard->commit;
+ $guard->commit if $guard;
return 1;
}
1 is returned on success, and 0 is returned if the object is
already at the specified position of the specified group.
-$group may be specified as a single scalar if only one
+$group may be specified as a single scalar if only one
grouping column is in use, or as a hashref of column => value pairs
if multiple grouping columns are in use.
=head2 insert
-Overrides the DBIC insert() method by providing a default
-position number. The default will be the number of rows in
+Overrides the DBIC insert() method by providing a default
+position number. The default will be the number of rows in
the table +1, thus positioning the new record at the last position.
=cut
my $self = shift;
# this is set by _ordered_internal_update()
- return $self->next::method(@_) if $self->{_ORDERED_INTERNAL_UPDATE};
+ return $self->next::method(@_) if $self->result_source->schema->{_ORDERED_INTERNAL_UPDATE};
my $upd = shift;
$self->set_inflated_columns($upd) if $upd;
$self->move_last;
- my @res;
- if (not defined wantarray) {
- $self->next::method( @_ );
- }
- elsif (wantarray) {
- @res = $self->next::method( @_ );
- }
- else {
- $res[0] = $self->next::method( @_ );
- }
+ $self->next::method( @_ );
$guard->commit;
- return wantarray ? @res : $res[0];
+
+ return $self;
}
# add the current position/group to the things we track old values for
my $shift_rs = $self->_group_rs-> search ({ $position_column => { -between => \@between } });
- # some databases (sqlite) are dumb and can not do a blanket
- # increment/decrement. So what we do here is check if the
- # position column is part of a unique constraint, and do a
- # one-by-one update if this is the case
-
+ # some databases (sqlite, pg, perhaps others) are dumb and can not do a
+ # blanket increment/decrement without violating a unique constraint.
+ # So what we do here is check if the position column is part of a unique
+ # constraint, and do a one-by-one update if this is the case.
my $rsrc = $self->result_source;
- if (grep { $_ eq $position_column } ( map { @$_ } (values %{{ $rsrc->unique_constraints }} ) ) ) {
-
- my @pcols = $rsrc->_pri_cols;
- my $cursor = $shift_rs->search ({}, { order_by => { "-$ord", $position_column }, columns => \@pcols } )->cursor;
- my $rs = $self->result_source->resultset;
-
- my @all_pks = $cursor->all;
- while (my $pks = shift @all_pks) {
- my $cond;
- for my $i (0.. $#pcols) {
- $cond->{$pcols[$i]} = $pks->[$i];
- }
-
- $rs->search($cond)->update ({ $position_column => \ "$position_column $op 1" } );
+ # set in case there are more cascades combined with $rs->update => $rs_update_all overrides
+ local $rsrc->schema->{_ORDERED_INTERNAL_UPDATE} = 1;
+ my @pcols = $rsrc->primary_columns;
+ if (
+ first { $_ eq $position_column } ( map { @$_ } (values %{{ $rsrc->unique_constraints }} ) )
+ ) {
+ my $clean_rs = $rsrc->resultset;
+
+ for ( $shift_rs->search (
+ {}, { order_by => { "-$ord", $position_column }, select => [$position_column, @pcols] }
+ )->cursor->all ) {
+ my $pos = shift @$_;
+ $clean_rs->find(@$_)->update ({ $position_column => $pos + ( ($op eq '+') ? 1 : -1 ) });
}
}
else {
}
}
-=head1 PRIVATE METHODS
-
-These methods are used internally. You should never have the
-need to use them.
-
-=head2 _group_rs
-This method returns a resultset containing all members of the row
-group (including the row itself).
-
-=cut
+# This method returns a resultset containing all members of the row
+# group (including the row itself).
sub _group_rs {
my $self = shift;
return $self->result_source->resultset->search({$self->_grouping_clause()});
}
-=head2 _siblings
-
-Returns an unordered resultset of all objects in the same group
-excluding the object you called this method on.
-
-=cut
+# Returns an unordered resultset of all objects in the same group
+# excluding the object you called this method on.
sub _siblings {
my $self = shift;
my $position_column = $self->position_column;
;
}
-=head2 _position
-
- my $num_pos = $item->_position;
-
-Returns the B<absolute numeric position> of the current object, with the
-first object being at position 1, its sibling at position 2 and so on.
-
-=cut
+# Returns the B<absolute numeric position> of the current object, with the
+# first object being at position 1, its sibling at position 2 and so on.
sub _position {
my $self = shift;
return $self->_position_from_value ($self->get_column ($self->position_column) );
}
-=head2 _grouping_clause
-
-This method returns one or more name=>value pairs for limiting a search
-by the grouping column(s). If the grouping column is not defined then
-this will return an empty list.
-
-=cut
+# This method returns one or more name=>value pairs for limiting a search
+# by the grouping column(s). If the grouping column is not defined then
+# this will return an empty list.
sub _grouping_clause {
my( $self ) = @_;
return map { $_ => $self->get_column($_) } $self->_grouping_columns();
}
-=head2 _get_grouping_columns
-
-Returns a list of the column names used for grouping, regardless of whether
-they were specified as an arrayref or a single string, and returns ()
-if there is no grouping.
-
-=cut
+# Returns a list of the column names used for grouping, regardless of whether
+# they were specified as an arrayref or a single string, and returns ()
+# if there is no grouping.
sub _grouping_columns {
my( $self ) = @_;
my $col = $self->grouping_column();
}
}
-=head2 _is_in_group
-
- $item->_is_in_group( {user => 'fred', list => 'work'} )
-
-Returns true if the object is in the group represented by hashref $other
-
-=cut
+# Returns true if the object is in the group represented by hashref $other
sub _is_in_group {
my ($self, $other) = @_;
my $current = {$self->_grouping_clause};
return 1;
}
-=head2 _ordered_internal_update
-
-This is a short-circuited method, that is used internally by this
-module to update positioning values in isolation (i.e. without
-triggering any of the positioning integrity code).
-
-Some day you might get confronted by datasets that have ambiguous
-positioning data (e.g. duplicate position values within the same group,
-in a table without unique constraints). When manually fixing such data
-keep in mind that you can not invoke L<DBIx::Class::Row/update> like
-you normally would, as it will get confused by the wrong data before
-having a chance to update the ill-defined row. If you really know what
-you are doing use this method which bypasses any hooks introduced by
-this module.
-
-=cut
-
+# This is a short-circuited method, that is used internally by this
+# module to update positioning values in isolation (i.e. without
+# triggering any of the positioning integrity code).
+#
+# Some day you might get confronted by datasets that have ambiguous
+# positioning data (e.g. duplicate position values within the same group,
+# in a table without unique constraints). When manually fixing such data
+# keep in mind that you can not invoke L<DBIx::Class::Row/update> like
+# you normally would, as it will get confused by the wrong data before
+# having a chance to update the ill-defined row. If you really know what
+# you are doing use this method which bypasses any hooks introduced by
+# this module.
sub _ordered_internal_update {
my $self = shift;
- local $self->{_ORDERED_INTERNAL_UPDATE} = 1;
+ local $self->result_source->schema->{_ORDERED_INTERNAL_UPDATE} = 1;
return $self->update (@_);
}
=head2 Multiple Moves
-Be careful when issuing move_* methods to multiple objects. If
-you've pre-loaded the objects then when you move one of the objects
-the position of the other object will not reflect their new value
-until you reload them from the database - see
-L<DBIx::Class::Row/discard_changes>.
-
-There are times when you will want to move objects as groups, such
-as changing the parent of several objects at once - this directly
-conflicts with this problem. One solution is for us to write a
-ResultSet class that supports a parent() method, for example. Another
-solution is to somehow automagically modify the objects that exist
-in the current object's result set to have the new position value.
+If you have multiple same-group result objects already loaded from storage,
+you need to be careful when executing C<move_*> operations on them:
+without a L</position_column> reload the L</_position_value> of the
+"siblings" will be out of sync with the underlying storage.
+
+Starting from version C<0.082800> DBIC will implicitly perform such
+reloads when the C<move_*> happens as a part of a transaction
+(a good example of such situation is C<< $ordered_resultset->delete_all >>).
+
+If it is not possible for you to wrap the entire call-chain in a transaction,
+you will need to call L<DBIx::Class::Row/discard_changes> to get an object
+up-to-date before proceeding, otherwise undefined behavior will result.
=head2 Default Values
projects / dbsrgits/DBIx-Class.git / blobdiff