Author image Zahatski Aliaksandr
and 1 contributors


Collection - CRUD framework


    package MyCollection;
    use Collection;
    @MyCollection::ISA = qw(Collection);


A collection - sometimes called a container - is simply an object that groups multiple elements into a single unit. Collection are used to store, retrieve, manipulate, and communicate aggregate data.

The primary advantages of a Collection framework are that it reduces programming effort by providing useful data structures and algorithms so you don't have to write them yourself.

The Collection framework consists of:

  • Wrapper Implementations - Add functionality, such as mirroring and lazy load, to other implementations.

  • Algorithms - methods that perform useful functions, such as caching.

This module has a task - to be a base class for ather Collections. You can inherit the methods _create, _delete, _fetch, _store and may be _prepare_record for new source of data. As you see this is similar to CRUD (Create - Read - Update- Delete).


        my $col = new MyCollection:: <some params>;
        #fetch objects or data by keys
        my $data = $col->fetch(1,2,3,4,5);
        #do something
        foreach my $item ( values %$data) {
            $_->attr->{inc} ++
        #You can use "lazy" functionality
        my $not_actualy_fetch = $col->get_lazy(6,7,8,9);
        #store changed data or objects
        #free memory

Sample from Collection::AutoSQL:

 my $beers = new Collection::AutoSQL::
  dbh     => $dbh,          #database connect
  table   => 'beers',       #table name
  field   => 'bid',         #key field (IDs), usually primary,autoincrement
  cut_key => 1;             #delete field 'bid' from readed records,
    my $heineken = $beers->fetch_one(1);
    #SELECT * FROM beers WHERE bid in (1)

Sample from Collection::Memcached:

    use Collection::Memcached;
    use Cache::Memcached;
    $memd = new Cache::Memcached {
    'servers' => [ "" ],
    'debug' => 0,
    'compress_threshold' => 10_000,
  my $collection = new Collection::Memcached:: $memd;
  my $collection_prefix = new Collection::Memcached:: $memd, 'prefix';


_store( {ID1 => <ref to object1>[, ID2 => <ref to object2>, ...]} )

Method for store changed objects. Called with ref to hash :

    ID1 => <reference to object1>
    [,ID2 => <reference to object2>,...]

_fetch(ID1[, ID2, ...])

Read data for given IDs. Must return reference to hash, where keys is IDs, values is readed data. For example:

    return {1=>[1..3],2=>[5..6]}

_create(<user defined>)

Create recods in data storage.


    user defined format

Result: Must return reference to hash, where keys is IDs, values is create records of data

_delete(ID1[, ID2, ...])

Delete records in data storage for given IDs.

Parametrs: array id IDs

    ID1, ID2, ...

or array of refs to HASHes

    {  id=>ID1 }, {id => ID2 }, ...

Format of parametrs depend method delete

_prepare_record( ID1, <reference to readed by _create record>)

Called before insert readed objects into collection. Must return ref to data or object, which will insert to callection.

create(<user defined>)

Public method for create objects.

fetch_one(ID1), get_one(ID1)

Public methods. Fetch object from collection for given ID. Return ref to objects or undef unless exists.

fetch(ID1 [, ID2, ...]) , get(ID1 [, ID2, ...])

Public methods. Fetch objects from collection for given IDs. Return ref to HASH, where where keys is IDs, values is objects refs.


release(ID1[, ID2, ...])

Release from collection objects with IDs. Only delete given keys from collection or all if empty


Call _store for changed objects. Store all loaded objects without parameters:

    $simple_collection->store(); #store all changed

or (for 1,2,6 IDs )


delete(ID1[,ID2, ...])

Release from collections and delete from storage (by calling _delete) objects ID1,ID2...



Method for base support lazy load objects from data storage. Not really return lazy object.


Collection::Memcached, Collection::Mem, Collection::AutoSQL, README


Zahatski Aliaksandr, <>


Copyright (C) 2005-2008 by Zahatski Aliaksandr

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.8.8 or, at your option, any later version of Perl 5 you may have available.

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