Relationship between block, controller and model - magento

Question

I am new guy to magento. I have seen $this->functionName() in template file of particular module. And then functionName() is placed under block. My question is Can I call any controller function or model function from block? Any relationship between block with controller and model?

Answer 1

Not sure but may be, this might help for calling model from block

public function getTagInfo()
{
    if (is_null($this->_tagInfo)) {
        $this->_tagInfo = Mage::getModel('tag/tag')
            ->load($this->getTagId());
    }
    return $this->_tagInfo;
} 

Regarding Controller: Controller's job is to do certain things to Models, and then tell the system it's layout rendering time. That's it. It's your Layout/Blocks job to display an HTML page in a certain way depending on the state of the system's Models.

Answer 2

Block Responsible for rendering content (everything from frontend, backend, emails, and more).

Controller Responsible for handling Http Requests and contain business logic. A controller usually interacts with Models. Controllers can implement one of the following interfaces HttpGetActionInterface, HttpPutActionInterface, HttpPostActionInterface, HttpDeleteActionInterface, etc. which gives context of what a controller is supposed to do with the data it receives.

Model Magento\Framework\Model\AbstractModel Represents a data object. For example an User, Product or Category. They contain getters and setters so that a controller knows what data it can use.

ResourceModel Magento\Framework\Model\ResourceModel\Db\AbstractDb Is used to provide a database resource like MySQL for your Model to interact with the database. The ResourceModel in Magento requires a table name and id of the primary key.

Collection Magento\Framework\Model\ResourceModel\Db\Collection\AbstractCollection Allows you to retrieve collections of your Models. A collection requires both the Model and ResourceModel.