Retrieve Distinct Field Values

Overview

In this guide, you can learn how to use the MongoDB PHP Library to retrieve the distinct values of a specified field across a collection.

Within a collection, different documents might contain different values for a single field. For example, one document in a restaurants collection has a borough value of 'Manhattan', and another has a borough value of 'Queens'. By using the MongoDB PHP Library, you can retrieve all the unique values that a field contains across multiple documents in a collection.

$collection = $client->sample_restaurants->restaurants;

MongoDB\Collection::distinct() Method

To retrieve the distinct values for a specified field, call the MongoDB\Collection::distinct() method and pass in the name of the field you want to find distinct values for.

$results = $collection->distinct('borough', []);
foreach ($results as $value) {
    echo json_encode($value), PHP_EOL;
}

"Bronx"
"Manhattan"
"Missing"
"Queens"
"Staten Island"

$results = $collection->distinct('borough', ['cuisine' => 'Italian']);
foreach ($results as $value) {
    echo json_encode($value), PHP_EOL;
}

"Bronx"
"Manhattan"
"Queens"
"Staten Island"

$query = ['borough' => 'Bronx', 'cuisine' => 'Pizza'];
$options = ['comment' => 'Bronx pizza restaurants'];
$results = $collection->distinct('name', $query, $options);
foreach ($results as $value) {
    echo json_encode($value), PHP_EOL;
}

"$1.25 Pizza"
"18 East Gunhill Pizza"
"2 Bros"
"Aenos Pizza"
"Alitalia Pizza Restaurant"
"Amici Pizza And Pasta"
"Angie'S Cafe Pizza"
...

API Documentation

To learn more about the distinct() method, see MongoDB\Collection::distinct() in the API documentation.