List Collections

Sometimes, you may need to list collections with MongoDB in a PHP environment to manage or analyze your database structure. In this tutorial, you will learn more about two ways to do this task.

Before getting started, you need to set up your environment. Start by installing the MongoDB PHP driver. If you do not have it, you can install it using Composer:

And then, you need to read this tutorial to learn how to build a connection between MongoDB and PHP.

Let's move on to following section to learn how to list collections using the listCollections function in PHP.

Show All Collections in PHP and MongoDB Using listCollections

Once you have ensured that the connection is enabled, you must select a specific database first. You can do that with the following code:

$database = $client->selectDatabase('my_database');

The $database object represents your MongoDB database, allowing you to interact with it. MongoDB provides access through a PHP callback that retrieves all collections using the listCollections() method. In the following code, you will see how to list all collections within the database:

$collections = $database->listCollections();

foreach ($collections as $collection) {
    echo $collection->getName() . "\n"; // Display the collection names
}

In this code, we list all collection names within the selected database. Each collection object includes additional metadata that you can access if needed.

Here is the complete example:

require_once "vendor/autoload.php";

$client = new MongoDB\Client("mongodb://localhost:27017");
$database = $database = $client->selectDatabase('my_database');
$collections = $database->listCollections();
 
foreach ($collections as $collection) {
    echo $collection->getName() . "\n";  
}

This will output:

users_collection

In the following section, you will learn how to list all collections based on another method.

Using listCollectionNames() to List MongoDB Collections in PHP

This method is a part of the MongoDB PHP library and allows you to fetch only the names of collections as an array of strings, skipping the additional metadata that listCollections() provides. Here is how it works:

$collectionNames = $database->listCollectionNames();

This method retrieves the names of all collections in the database as an array of strings. It is more clear compared to listCollections() because it does not include metadata.

Here is the full example:

require_once "vendor/autoload.php";
$client = new MongoDB\Client("mongodb://localhost:27017");
$database = $client->my_database;

$collectionNames = $database->listCollectionNames();

foreach ($collectionNames as $name) {
    echo $name . "\n";  
}

It will print: 

//=> It displays all names of collections without metadata
users
posts

You can achieve the same task using another method through a command. Let us move on to the following section to understand how it works.

Using the Command Method to List MongoDB Collections in PHP

The MongoDB library has another predefined function. It is the command. It allows you to run any command on the database within the PHP environment.

You will add a command to MongoDB to retrieve all collections using this function and then wrap it in PHP to convert the response into an array.

Here is an example:

$command = $database->command(['listCollections' => 1]);

This executes the listCollections command directly on the database. The listCollections command is a native MongoDB command that lists all collections in a database. The parameter 1 is required to indicate that the command should execute.

$collections = $command->toArray();

This function returns a cursor-like object and toArray() function converts the results into an array for easier processing.

You can list all collection names by looping through them. Here is an example:

foreach ($collections as $collection) {
    echo $collection->name . "\n";
}

Here is the complete example:

require_once "vendor/autoload.php";
$client = new MongoDB\Client("mongodb://localhost:27017");
$database = $client->my_database;

// Run the 'listCollections' command manually
$command = $database->command(['listCollections' => 1]);

$collections = $command->toArray();

foreach ($collections as $collection) {
    echo $collection->name . "\n";  
}

You can also use executeCommand function to interact with MongoDB using the MongoDB Driver's low-level API, which gives more granular control over commands and queries. Here is the full example:

require_once "vendor/autoload.php";
$manager = new MongoDB\Driver\Manager("mongodb://localhost:27017");

$command = new MongoDB\Driver\Command(['listCollections' => 1]);
$cursor = $manager->executeCommand('my_database', $command);

foreach ($cursor as $collection) {
    echo $collection->name . "\n";  
}

This method allows you to send any MongoDB command directly to the server and retrieve results in a cursor object.

Anyway, let's move on to the deprecated and removed functions.

Deprecated and Removed Functions

The getCollectionNames() method was used in older versions of the MongoDB PHP driver (pre-mongodb/mongodb library). It is now deprecated and removed in favor of listCollectionNames() and listCollections().

If you encounter getCollectionNames() in older codebases, you should replace it with modern equivalents. Here is how you can migrate or understand its use:

// Legacy MongoDB driver (pre-`mongodb/mongodb` library)
$mongo = new MongoClient("mongodb://localhost:27017");
$database = $mongo->selectDB("my_database");

// Get collection names
$collections = $database->getCollectionNames();

foreach ($collections as $name) {
    echo $name . "\n";
}

This method worked similarly to listCollectionNames(), but it is no longer supported in the current mongodb/mongodb library.

Here is a table that shows you the key differences between each function:

Let's summarize it.

Wrapping Up

Listing all collections in a MongoDB database within the PHP environment is an essential tool for managing and understanding your database structure. It provides functions like listCollections, listCollectionNames, and direct command execution.

These tools enable you to retrieve detailed metadata or simply the collection names, depending on your requirements.

Here is a quick recap:

Thank you for reading. Happy coding!