Collection Component

Collection Component

Overview

Phalcon\Collection is an object oriented array. It offers speed, as well as implementations of various PHP interfaces. These are:

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
    'year'   => 1776,
];
$collection = new Collection($data);

Constructor

You can construct the object as any other object in PHP. However, the constructor accepts an optional array parameter, which will populate the object for you.

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
    'year'   => 1776,
];
$collection = new Collection($data);

Reusing

You can also reuse the component, by repopulating it. Phalcon\Collection exposes the clear() and init() methods, which will clear and repopulate the internal array respectively,

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
    'year'   => 1776,
];
$collection = new Collection($data);
echo $collection->count(); // 2
$data = [
    'year' => 1776,
];
$collection->clear();
$collection->init($data);
echo $collection->count(); // 1

Get

As mentioned above, Phalcon\Collection implements several interfaces, in order to make the component as flexible as possible. Retrieving data stored in an element can be done by using:

Property
__get()
array based get ($collection[$element])
offsetGet()
get()The fastest way is by using the property syntax:

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
    'year'   => 1776,
];
$collection = new Collection($data);
echo $collection->year;                    // 1776

You can use __get($element) but it is not advisable as it is much slower than the property syntax. The same applies to offsetGet

echo $collection->__get('year');           // 1776
echo $collection['year'];                  // 1776
echo $collection->offsetGet('year');       // 1776
echo $collection->get('year', 1776, true); // 1776

public function get(string $element, mixed $defaultValue = null, bool $insensitive = true):  mixed

Using get() offers two extra parameters. When $defaultValue is defined in the call, if the element is not found, $defaultValue will be returned. By default $insensitive is set to true, making searches in the collection case insensitive. Setting this value to false will make the search for the element case sensitive.

Has

To check whether an element exists or not in the collection, you can use the following:

isset() on the property
__isset()
array based isset (isset($coollection[$element]))
offsetExists()
has()The fastest way is by using the property syntax:

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
    'year'   => 1776,
];
$collection = new Collection($data);
echo isset($collection->year); // true

You can use __isset(element) but it is not advisable as it is much slower than the property syntax. The same applies to offsetExists

echo $collection->__isset('year');        // true
echo isset($collection['year']);          // true
echo $collection->offsetExists('year');   // true
echo $collection->has('year', true);      // true

public function has(string $element, bool $insensitive = true):  bool

Using has() offers an extra parameter. By default $insensitive is set to true, making searches in the collection case insensitive. Setting this value to false will make the search for the element case sensitive.

echo $collection->has('YEAR', true);      // true
echo $collection->has('YEAR', false);     // false

Set

To set an element in the collection, you can use the following:

assign the value to the property
__set()
array based assignment
offsetSet()
set()The fastest way is by using the property syntax:

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
];
$collection = new Collection($data);
$collection->year = 1776;

You can use __set($element, $value) but it is not advisable as it is much slower than the property syntax. The same applies to offsetSet

$collection->__set('year', 1776);
$collection['year'] = 1776;
$collection->offsetSet('year', 1776);
$collection->set('year', 1776);

Remove

To remove an element in the collection, you can use the following:

unset the property
__unset()
array based unset
offsetUnset()
remove()The fastest way is by using the property syntax:

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
];
$collection = new Collection($data);
unset($collection->year);

You can use __unset($element) but it is not advisable as it is much slower than the property syntax. The same applies to offsetUnset

$collection->__unset('year');
unset($collection['year']);
$collection->offsetUnset('year');
$collection->remove('year');

public function remove(string $element, bool $insensitive = true):  void

Using remove() offers an extra parameter. By default $insensitive is set to true, making searches in the collection case insensitive. Setting this value to false will make the search for the element case sensitive.

$collection->remove('YEAR', true);
$collection->remove('YEAR', false);

Iteration

Since the collection object implements \IteratorAggregate, you can iterate through the object with ease. The method getIterator() returns an ArrayIterator() object

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
    'year'   => 1776,
];
$collection = new Collection($data);
foreach ($collection as $key => $value) {
    echo $key . ' - ' . $value . PHP_EOL;
}

Count

The implementation of the \Countable interface exposes the count() method, which stores the number of elements in the collection.

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
    'year'   => 1776,
];
$collection = new Collection($data);
echo $collection->count();    // 2

Serialization

The \Serializable and \JsonSerializable interfaces expose methods that allow you to serialize and unserialize the object. serialize() and unserialize() use PHP’s serialize and unserialize functions. jsonSerialize() returns an array which can be used with json_encode to serialize the object.

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
    'year'   => 1776,
];
$collection = new Collection($data);
echo $collection->serialize();    // a:2:{s:6:"colors";a:3:{i:0;s:3:"red";i:1;s:5:"white";i:2;s:4:"blue";}s:4:"year";i:1776;}
$serialized = 'a:2:{s:6:"colors";a:3:{i:0;s:3:"red";i:1;s:5:"white";i:2;s:4:"blue";}s:4:"year";i:1776;}';
$collection->unserialize($serialized);
echo $collection->jsonSerialize(); // $data

Transformations

Phalcon\Collection also exposes two transformation methods: toArray() and toJson(int $options). toArray() returns the object transformed as an array. This method returns the same array as jsonSerialize().

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
    'year'   => 1776,
];
$collection = new Collection($data);
echo $collection->toArray();  // $data

toJson(int $options) returns a JSON representation of the object. It uses json_encode internally and accepts a parameter, which represents the flags that json_encode accepts. By default the options are set up with the value 74, (RFC4327) which translates to:

JSON_HEX_TAG
JSON_HEX_APOS
JSON_HEX_AMP
JSON_HEX_QUOT
JSON_UNESCAPED_SLASHESYou can pass any valid flags to the method according to your needs.

<?php
use Phalcon\Collection;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
    'year'   => 1776,
];
$collection = new Collection($data);
echo $collection->toJson();    // ["red","white","blue"],"year":1776}
echo $collection->toJson(74 + JSON_PRETTY_PRINT);
/**
{
    "colors": [
        "red",
        "white",
        "blue"
    ],
    "year": 1776
}
*/

Read Only

Phalcon also offers a component that can be used in a read-only fashion. Phalcon\Collection\ReadOnly can serve as a collection in your application that can only be populated with initial data but not allowing its contents to be changed throughout the application.

<?php
use Phalcon\Collection\ReadOnly;
$data = [
    'colors' => [
        'red',
        'white',
        'blue',
    ],
    'year'   => 1776,
];
$collection = new ReadOnly($data);
echo $collection->toJson();    // ["red","white","blue"],"year":1776}
$collection->set('colors', ['red']); // Exception