name TEXT NOT NULL,
position INTEGER NOT NULL
);
- # Optional: group_id INTEGER NOT NULL
-In your Schema or DB class add Ordered to the top
+Optionally, add one or more columns to specify groupings, allowing you
+to maintain independent ordered lists within one table:
+
+ CREATE TABLE items (
+ item_id INTEGER PRIMARY KEY AUTOINCREMENT,
+ name TEXT NOT NULL,
+ position INTEGER NOT NULL,
+ group_id INTEGER NOT NULL
+ );
+
+Or even
+
+ CREATE TABLE items (
+ item_id INTEGER PRIMARY KEY AUTOINCREMENT,
+ name TEXT NOT NULL,
+ position INTEGER NOT NULL,
+ group_id INTEGER NOT NULL,
+ other_group_id INTEGER NOT NULL
+ );
+
+In your Schema or DB class add "Ordered" to the top
of the component list.
__PACKAGE__->load_components(qw( Ordered ... ));
package My::Item;
__PACKAGE__->position_column('position');
- __PACKAGE__->grouping_column('group_id'); # optional
-Thats it, now you can change the position of your objects.
+If you are using one grouping column, specify it as follows:
+
+ __PACKAGE__->grouping_column('group_id');
+
+Or if you have multiple grouping columns:
+
+ __PACKAGE__->grouping_column(['group_id', 'other_group_id']);
+
+That's it, now you can change the position of your objects.
#!/use/bin/perl
use My::Item;
$item->move_first();
$item->move_last();
$item->move_to( $position );
+ $item->move_to_group( 'groupname' );
+ $item->move_to_group( 'groupname', $position );
+ $item->move_to_group( {group_id=>'groupname', 'other_group_id=>'othergroupname'} );
+ $item->move_to_group( {group_id=>'groupname', 'other_group_id=>'othergroupname'}, $position );
=head1 DESCRIPTION
__PACKAGE__->position_column('position');
Sets and retrieves the name of the column that stores the
-positional value of each record. Default to "position".
+positional value of each record. Defaults to "position".
=cut
__PACKAGE__->grouping_column('group_id');
-This method specified a column to limit all queries in
+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.
my $rs = $item->siblings();
my @siblings = $item->siblings();
-Returns either a result set or an array of all other objects
+Returns either a resultset or an array of all other objects
excluding the one you called it on.
=cut
my $sibling = $item->first_sibling();
Returns the first sibling object, or 0 if the first sibling
-is this sibliing.
+is this sibling.
=cut
my $sibling = $item->last_sibling();
-Return 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
my $sibling = $item->previous_sibling();
-Returns the sibling that resides one position back. Undef
-is returned if the current object is the first one.
+Returns the sibling that resides one position back. Returns undef
+if the current object is the first one.
=cut
my $sibling = $item->next_sibling();
-Returns the sibling that resides one position foward. Undef
-is returned if the current object is the last one.
+Returns the sibling that resides one position forward. Returns undef
+if the current object is the last one.
=cut
$item->move_previous();
-Swaps position with the sibling on position previous in the list.
-1 is returned on success, and 0 is returned if the objects is already
-the first one.
+Swaps position with the sibling in the position previous in
+the list. Returns 1 on success, and 0 if the object is
+already the first one.
=cut
$item->move_next();
-Swaps position with the sibling in the next position. 1 is returned on
-success, and 0 is returned if the object is already the last in the list.
+Swaps position with the sibling in the next position in the
+list. Returns 1 on success, and 0 if the object is already
+the last in the list.
=cut
$item->move_first();
-Moves the object to the first position. 1 is returned on
-success, and 0 is returned if the object is already the first.
+Moves the object to the first position in the list. Returns 1
+on success, and 0 if the object is already the first.
=cut
$item->move_last();
-Moves the object to the very last position. 1 is returned on
-success, and 0 is returned if the object is already the last one.
+Moves the object to the last position in the list. Returns 1
+on success, and 0 if the object is already the last one.
=cut
$item->move_to( $position );
-Moves the object to the specified position. 1 is returned on
-success, and 0 is returned if the object is already at the
-specified position.
+Moves the object to the specified position. Returns 1 on
+success, and 0 if the object is already at the specified
+position.
=cut
1 is returned on success, and 0 is returned if the object is
already at the specified position of the specified group.
-$group should be supplied as a hashref of column => value pairs,
-e.g. if the grouping columns were 'user' and 'list',
-{ user => 'fred', list => 'work' }.
+$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.
=cut
my $pos_col = $self->position_column;
- # is there a chance in hell of this working?
# if any of our grouping columns have been changed
-$DB::single=1;
if (grep {$_} map {exists $changes{$_}} $self->_grouping_columns ) {
# create new_group by taking the current group and inserting changes
=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 even returns ()
-if we're not grouping.
+they were specified as an arrayref or a single string, and returns ()
+if there is no grouping.
=cut
sub _grouping_columns {
}
-
-
1;
__END__
If a position is not specified for an insert than a position
will be chosen based on COUNT(*)+1. But, it first selects the
-count then inserts the record. The space of time between select
+count, and then inserts the record. The space of time between select
and insert introduces a race condition. To fix this we need the
ability to lock tables in DBIC. I've added an entry in the TODO
about this.
projects / dbsrgits/DBIx-Class.git / blobdiff