MongoDB PHP – Connecting to MongoDB

Preamble

The MongoClient class is used to connect to the mongodb database. It allows you to connect to mongodb (connect method) and disconnect (close method), as well as select the database (selectDB method) and the collection to communicate with (selectCollection method).

The connection is standard:

// Connect to mongodb
$con = new MongoClient();
// select the test database
$con-> test;

We could also select the database by using the selectDB method:

$con-> selectDB(test);

In fact, it would be the same as if you were installing the database in the console using the use test command.

Once the work is done, we can close the connection using the close method. In principle, mongoDB can automatically close connections that do not work. However, under certain conditions, it may be necessary to explicitly close the connection, for example, to establish a new connection immediately.

$con = new MongoClient();
$con-> test;
$con-> close();

By installing the dd, you can select the collection:

// Connect to mongodb
$con = new MongoClient();
// select the test database and the person's collection
$con-> test -> persons;

Either we can explicitly apply the selectCollection method

$con-> selectDB(test)-> selectCollection(persons);

In the mongo console we add a document to the collection, even if the collection does not exist yet. In this case, it was automatically created. In PHP it is the same. Now we connect to the person’s collection. And even if it does not exist, it will be created if we add some data to it later.

Another method that the MongoClient class has is the listDBs method. It allows us to get all databases in MongoDB:

$con = new MongoClient();
print_r($con-> listDBs());

This method returns data in an associative array format:

Array
(
[databases] => Array
(
[0] => Array
(
[name] => local
[sizeOnDisk] => 83886080
[empty] =>
)
[1] => Array
(
[name] => test
[sizeOnDisk] => 218103808
[empty] =>
)
)
[totalSize] => 301989888
[ok] => 1
)

Similarly, using the listCollections method, we can obtain all collections in a particular database:

$con = new MongoClient();
$list= $con-> test-> listCollections();
foreach ($list as $collection) {
echo "<p>" . $collection . "</p>";
}

If we just want the names of all collections, we can use the getCollectionNames() method:

$con = new MongoClient();
$list= $con-> test-> getCollectionNames();
foreach ($list as $collection) {
echo "<p>" . $collection . "</p>";
}

PHP MongoDB – Installation and Connection

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