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Shoaib Akbar
Shoaib Akbar

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Filtering and Customizing Arrays in PHP: A Step-by-Step Guide

#php #beginners #codenewbie #learning

We'll explore how to filter an array of books to display only those written by a specific author or by relaeseYear.

Array I'll use in examples

$books = [
[
'name' => 'Do Androids Dream of Electric Sheep',
'author' => 'Philip K. Dick',
'releaseYear' => 1968,
'purchaseURL' => 'http://example.com'
],
[
'name' => 'Project Hail Mary',
'author' => 'Andy Weir',
'releaseYear' => 2021,
'purchaseURL' => 'http://example.com'
],
[
'name' => 'The Martian',
'author' => 'Andy Weir',
'releaseYear' => 2011,
'purchaseURL' => 'http://example.com'
]
];

We'll start with a basic foreach loop.

foreach($books as $book) { if($book['author'] === "Andy Weir") { echo "<a href='#'><li>". $book['name'] ."</li></a>"; } }
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Creating a Filter Function by Author and releaseYear

function filterByAuthor($books) { $filteredBooks = []; foreach($books as $book){ if($book['author'] === "Andy Weir") { $filteredBooks[] = $book; } } return $filteredBooks; } function filterByReleaseYear($books) { $filteredBooks = []; foreach($books as $book){ if($book['releaseYear'] === 2011) { $filteredBooks[] = $book; } } return $filteredBooks; } ?> <ul> <?php foreach(filterByAuthor($books) as $book) { echo "<a href='#'><li>". $book['name'] ."</li></a>"; } ?> </ul>
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Creating a Generalized Filter Function to add more flexibility

function filter($items, $key, $value) { $filteredItems = []; foreach($items as $item){ if($item[$key] === $value) { $filteredItems[] = $item; } } return $filteredItems; } $filterByAuthor = filter($books, 'author', 'Andy Weir'); $filteredByReleaseYear = filter($books, 'releaseYear', 2011); ?> <ul> <?php foreach($filterByAuthor as $book) { echo "<a href='#'><li>". $book['name'] ."</li></a>"; } ?> </ul>
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Using Anonymous Functions for Filtering to add even more flexibility to the conditional statement

 function filter($items, $fn) { $filteredItems = []; foreach($items as $item){ if($fn($item)) { $filteredItems[] = $item; } } return $filteredItems; } $filterByAuthor = filter($books, function($book){ return $book['author'] === 'Andy Weir'; }); $filteredByReleaseYear = filter($books, function($book){ return $book['releaseYear'] >= 2000; }); ?> <ul> <?php foreach($filterByAuthor as $book) : ?> <a href='#'><li> <?= $book['name']; ?> </li></a> <?php endforeach; ?> </ul> <ul> <?php foreach($filteredByReleaseYear as $book) : ?> <a href='#'><li> <?= $book['name']; ?> </li></a> <?php endforeach; ?> </ul>
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PHP build-in array_filter() solves this exactly!

$filterByAuthor = array_filter($books, function($book){ return $book['author'] === 'Andy Weir'; }); $filteredByReleaseYear = array_filter($books, function($book){ return $book['releaseYear'] >= 1950; }); ?> <ul> <?php foreach($filterByAuthor as $book) : ?> <a href='#'><li> <?= $book['name']; ?> </li></a> <?php endforeach; ?> </ul> <ul> <?php foreach($filteredByReleaseYear as $book) : ?> <a href='#'><li> <?= $book['name']; ?> </li></a> <?php endforeach; ?> </ul>
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Top comments (2)

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Nicolas LUDOVIC •

Since PHP 7.4 you can use arrow function. It will make your filter more readable.

//Before array_filter($books, function($book){ return $book['releaseYear'] >= 1950; }); //After array_filter($books, fn ($book) => $book['releaseYear'] >= 1950);
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Shoaib Akbar •

yes true, thanks for your value addition