I am coding application using Perl Catalyst framework which uses
DBIx::Class for database manipulation. I also have a table of users that
are ordered in some kind of a tree. My Postgres table schema looks like:
Columns in table "users":
- user_id (primary key, integer)
- username (varchar)
- password (varchar)
(some other columns with user data)
- parent_id (integer)
so my schema looks like:
__PACKAGE__->load_components("Core");
__PACKAGE__->table("users");
__PACKAGE__->add_columns(
"user_id",
{ data_type => "integer", default_value =>
"nextval('public.user_user_id_seq'::text)", is_nullable => 0, size =>
4, },
"username",
{ data_type => "character varying", default_value => undef,
is_nullable => 0, size => 32, },
"password",
{ data_type => "character varying", default_value => undef, is_nullable
=> 0, size => 128 },
# ........ other user data ......
"parent_id",
{ data_type => "integer", default_value => undef, is_nullable => 1,
size => 4 },
);
__PACKAGE__->set_primary_key("user_id");
So each element in this table is let's say $user ... So I am looking for
a solution how to write the following functions:
1.) get_all_children - a function that would return a reference to all
children, grandchildren, grandgrandchildren (unlimited levels) of a
single $user ... Function should also be able to handle "order by" (e.g.
"order by username desc"), limit (e.g. "limit 10") and offset (e.g.
"offset 20") so the returned data would be suitable to deliver on a webpage
2.) is_parent_of - a function that would return true/false if $user is a
parent,grandparent,grandgrand....(again unlimited levels) of $someotheruser
I understand the concept - recursive function calls will be needed - but
I don't know how to code these functions
so they would be reusable and without any (levels/depth) limits. Mostly
all data is only 2 - 3 levels deep but
I would like to have functions that would be able to handle any depth.
Until now I only used simple select/update/insert calls with DBIx so
this whole trees concept
is just too much for me...
Thank you for any solution!
JC.
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