Class 'MongoClient' not found

You have not installed MongoDB PHP driver please see this link http://www.php.net/manual/en/mongo.installation.php

Update sources

sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80 --recv 7F0CEB10echo 'deb http://downloads-distro.mongodb.org/repo/ubuntu-upstart dist 10gen' | sudo tee /etc/apt/sources.list.d/mongodb.listsudo apt-get update

Install MongoDB PHP Driver

sudo apt-get install php5-dev php5-cli php-pear -ysudo pecl install mongo

Open your php.ini file and add to it:

extension=mongo.so

Restart apache

sudo /etc/init.d/apache2 restart

Other helping info:

this should help to find your php.ini file:

php -i | grep 'Configuration File'

On Ubuntu it shows this:

Configuration File (php.ini) Path => /etc/php5/cliLoaded Configuration File => /etc/php5/cli/php.ini

take a note, that you run this command from cli (command line) so for your true php.ini go to folder apache2 instead of cli :)

For those arriving on this page with PHP 7 installed:

The MongoCLient class was provided by pecl install mongo.But pecl/mongo is not available for php7 and deprecated in favor of pecl/mongodb. But with pecl/mongodb you'll need to use MongoDB\Driver\Manager instead of MongoClient (warning on page says so too).

See here for further reading.

This said, you will need an abstraction layer on top of the PHP MongoDB\Driver\Manager. This is provided by mongodb/mongo-php-library.

You will need to refactor stuff like:

• \MongoClient to \MongoDB\Client
• \MongoCollection to \MongoDB\Collection
• \MongoClient->selectDB to \MongoDB\Client->selectDatabase
• \MongoClient->listDBs to \MongoDB\Client->listDatabases
  • also output is not an array but an iterator, so you'll need to use iterator_to_array, along with edits to how you use the resulting object
• \MongoCollection->getName to \MongoDB\Collection->getCollectionName
• \MongoCollection->update to \MongoDB\Collection->updateOne or updateMany
• \MongoCollection->remove to \MongoDB\Collection->deleteOne
• \MongoCollection->batchInsert to \MongoDB\Collection->insertMany

The answer is indeed to follow the instructions.I was missing the very important require line that must come before creating the new mongodb object:

<?phprequire 'vendor/autoload.php';$client = new MongoDB\Client("mongodb://localhost:27017");

And of course you need to run this command in the root of your project as per the instructions:

composer require mongodb/mongodb