Collections

• Usage

Collections are, as the name suggests, objects that contain a collection of values. You can iterate over collections and access items just like you would with an array. In addition to this the class also implements a set of useful methods.

The result set class of the query builder extends the collection class.

Usage

Creating a collection is easy. You can create an empty collection or pass a set of values to the constructor.

$collection1 = new Collection;

$collection2 = new Collection([1, 2, 3]);

Adding a value to the collection is done using the put method.

$collection = new Collection;

$collection->put(0, 'foo');

$collection[1] = 'bar';

You can check if an item exists in the collection using the has method.

$collection = new Collection(['foo' => 'bar']);

var_dump($collection->has('foo')); // true

var_dump($collection->has('bar')); // false

You can also use the collection as an array with the isset function but it will return false for null values while the has method will return true as long as the key exists.

The get method can be used to retrieve an item from the collection. You can also specify a default value to return if the item doesn't exist using the optional second parameter. It is also possible to retrieve items by using the collection as an array.

$collection = new Collection(['foo' => 'bar']);

var_dump($collection->get('foo')); // 'bar'

var_dump($collection->get('bar', 'baz')); // 'baz'

var_dump($collection['foo']); // 'bar'

Accessing a non-existing key when using the collection as an array will result in a OutOfBoundsException exception.

Deleting an item from the collection can be done using the remove method or by using the unset function while using the collection as an array.

$collection = new Collection(['foo' => 'bar', 'baz' => 'bax']);

$collection->remove('foo');

unset($collection['baz']);

If you want to delete all items from the collection then you'll have to use the clear method.

$collection = new Collection(['foo' => 'bar', 'baz' => 'bax']);

$collection->clear();

Appending a value to the collection is done using the push method or by treating the collection as an array.

$collection = new Collection;

$collection->push('foo');

$collection[] = 'bar';

Both the getItems and getValues methods will return an array containing all if the collection items. The difference is that getItems will maintain the keys while getValues will not.

$collection = new Collection([1 => 'foo', 2 => 'bar']);

var_dump($collection->getItems()); // [1 => 'foo', 2 => 'bar']

var_dump($collection->getValues()); // [0 => 'foo', 1 => 'bar']

You can also reset the keys in the collection using the resetKeys method.

Prepending values to the collection can be done using the unshift method.

$collection = new Collection([2]);

$collection->unshift(1);

Shifting a value off of the collection can be done with the shift method.

$collection = new Collection([1, 2, 3]);

var_dump($collection->shift()); // 1

var_dump($collection->shift()); // 2

var_dump($collection->shift()); // 3

Popping a value off of the collection is done using the pop method.

$collection = new Collection([1, 2, 3]);

var_dump($collection->pop()); // 3

var_dump($collection->pop()); // 2

var_dump($collection->pop()); // 1

You can get the number of items in the collection by using the count method or by using the count function on the collection.

$collection = new Collection(['foo' => 'bar', 'baz' => 'bax']);

var_dump($collection->count()); // 2

var_dump(count($collection)); // 2

Checking if a collection is empty is done using the isEmpty method.

$collection = new Collection([1, 2, 3]);

var_dump($collection->isEmpty()); // false

$collection->clear();

var_dump($collection->isEmpty()); // true

You can sort items in a collection using the sort method.

$collection = new Collection([2, 1, 3, 5, 6, 4]);

$collection->sort(function($a, $b)
{
	if($a == $b)
	{
		return 0;
	}

	return ($a < $b) ? -1 : 1;
});

Index association will be maintained by default but you can set the optional second parameter to false to disable this.

A collection can be chunked into a collection of n sized collections using the chunk method. This can be useful when rendering content in a grid system like the one available in Bootstrap.

$collection = new Collection([1, 2, 3, 4, 5, 6]);

$chunked = $collection->chunk(2);

You can shuffle the contents of a collection using the shuffle method.

$collection = new Collection([1, 2, 3, 4, 5, 6]);

$collection->shuffle();

The each method allows you to modify your collection items using a callable.

$collection = new Collection([1, 2, 3]);

$collection->each(function($value, $key)
{
	return $key . ':' . $value;
});

The map method works just like the each method except that it returns a new collection instead of modifying the existing one

$collection = new Collection([1, 2, 3]);

$newCollection = $collection->map(function($value, $key)
{
	return $key . ':' . $value;
});

You can filter a collection and remove unwanted items using a callable with the filter method. The callable can also accept a second parameter if you need to filter items using the key. If no callable is passed then it will just filter out all falsy values.

$collection = new Collection([1, 2, 3, 'foo', 4]);

$filtered = $collection->filter(function($value)
{
	return is_int($value);
});

Two collections can be merged using the merge method.

$collection1 = new Collection([1, 2, 3]);

$collection2 = new Collection([4, 5, 6]);

$merged = $collection1->merge($collection2);