All controllers in OpenCart share a common ancestor, the Controller class, located in the DIR_APPLICATION/system/engine/controller.php file. Note that DIR_APPLICATION is the path to your application directory, and is defined in the OpenCart config.php file.
In object oriented terms, the Controller class is called a base class. It contains common methods and data definitions [...]

[Read more →]

An OpenCart top level controller is responsible for orchestrating the complete construction of an OpenCart page.
As an example, the ControllerCheckoutCart controller class is responsible for coordinating the model data and the template view necessary to create a checkout cart page for the client.
Another example is the ControllerCommonHome controller class, which is responsible for the main [...]

[Read more →]

The OpenCart Controller class contains a render method that is used to produce HTML pages output by all OpenCart classes that inherit from Controller class.
Here is how it works.
Each time a page is rendered, it is done with one top level controller. The top level controller may contain zero or more child controllers and [...]

[Read more →]