Collections and lazy streams#

Transform records without changing the original collection. Callbacks receive value and key. filter() preserves keys; use values() before returning a JSON list. Dot paths work with arrays, public properties and Elang models.

Working example#

use Elang\Support\{Collection, LazyCollection};

$stock = new Collection([
    ['sku' => 'A', 'quantity' => 5],
    ['sku' => 'B', 'quantity' => 0],
    ['sku' => 'C', 'quantity' => 3],
]);
$available = $stock->filter(fn ($row) => $row['quantity'] > 0)->values();
$total = $available->sum('quantity'); // 8
$codes = $available->pluck('sku')->all(); // ['A', 'C']

$stream = new LazyCollection(function () {
    for ($id = 1; $id <= 1000000; $id++) yield $id;
});
$first = $stream->filter(fn ($id) => $id % 2 === 1)->take(3)->collect();
// [1, 3, 5]; the source is read only through 5.

Collection operations#

Available operations: map, filter, reject, each, first, reduce, pluck, keyBy, groupBy, where, sortBy, take, chunk, sum, keys, values, get, all and toArray. where() uses strict equality. Objects inside a collection are not deep-cloned.

Bounded lazy traversal#

A lazy collection takes a factory that returns a fresh iterable on every traversal. It supports map, filter, take, chunk, each and collect. collect() materializes the result: take a bounded subset first when processing large input. Chunk sizes must be positive; take counts cannot be negative. This is an in-memory transformation API, not an ORM query builder.

Try it together#

Run the complete catalogue example from an application with the optional ORM installed. It uses a disposable in-memory database and a fake partner API. Expected output includes "checks":"passed". The example covers entity relationships, fetch joins, resources, collections and HTTP/kernel assertions.

php vendor/elang/framework/examples/orm-catalog/run.php

Next step · GitHub: complete runnable source

Common mistakes#