Add Component Structure and MVC Implementation

Component-Structure-and-MVC-Implementation.md

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+## Overview
+Joomla 5 follows the **Model-View-Controller (MVC)** design pattern, which separates data processing (Model), presentation (View), and user interaction (Controller). This separation enhances modularity, making it easier to extend and maintain components without affecting other sections.
+
+Joomla’s autoloading system allows developers to structure controllers, views, and models in separate files without manually including them. However, proper **naming conventions** must be followed to ensure smooth loading and execution.
+
+## MVC Structure in Joomla 5
+### **File and Naming Conventions**
+Joomla uses **{ComponentName}** as the standard reference for a component (e.g., `Content`). Case sensitivity is important:
+- `{ComponentName}` → CamelCase format
+- `{componentname}` → Lowercase format
+- `{ViewName}` → View name in CamelCase
+- `{viewname}` → Lowercase view name
+- `{ModelName}` → Model name in CamelCase
+- `{modelname}` → Lowercase model name
+- `{ControllerName}` → Controller name in CamelCase
+- `{controllername}` → Lowercase controller name
+
+### **Reserved Words**
+Certain words cannot be used as part of class or component names. For example:
+- The word **"model"** can only appear as the second part of a model class name (e.g., `ContentModelArticles`).
+- Component names cannot contain "Model," as controllers inherit naming conventions from models.
+
+## **Installation Package and File Placement**
+All Joomla extensions must be packaged as a `.zip` file and contain at least the following directories:
+
+```
+com_{componentname}/
+├── site/
+└── admin/
+```
+- **`site/`**: Holds frontend files.
+- **`admin/`**: Holds backend (administrator) files.
+
+When installed:
+- `site/` is placed under `/components/com_{componentname}`
+- `admin/` is placed under `/administrator/components/com_{componentname}`
+
+## **Frontend (`/site`) Component Structure**
+
+### **Main Entry Point**
+- **`site/{componentname}.php`** → The component’s main entry file.
+
+### **Controller**
+- **`site/controller.php`** → Default controller.
+- Defines `{ComponentName}Controller`, extending `\Joomla\CMS\MVC\Controller\BaseController`.
+- Additional controllers go under `site/controllers/{controllername}.php`.
+
+### **Views**
+- **`site/views/{viewname}/view.html.php`** → Main view file.
+- Declares `{ComponentName}View{ViewName}` extending `\Joomla\CMS\MVC\View\HtmlView`.
+- Templates for the view reside in:
+  ```
+  site/views/{viewname}/tmpl/
+  ├── default.php  (Main template file)
+  ```
+
+### **Models**
+- **`site/models/{modelname}.php`** → Model class.
+- Declares `{ComponentName}Model{ModelName}` extending `\Joomla\CMS\MVC\Model\BaseDatabaseModel`.
+- By default, a view loads a model with the same name (if it exists).
+
+## **Backend (`/admin`) Component Structure**
+The `/admin` directory follows the same structure as `/site`, but it is entirely separate.
+
+Key points:
+- **Admin and site components are distinct**; sharing code is optional.
+- **Shared models** can reduce code duplication.
+- To avoid security risks, ensure site users cannot execute admin actions.
+
+### **Code Sharing Between Site and Admin**
+Joomla supports shared models and utility classes between frontend and backend. When sharing code:
+- Place shared classes in a neutral directory (`/models`, `/helpers`).
+- Ensure class design prevents unauthorized access to admin functionalities.
+
+## **Naming Validation in Joomla Core**
+Joomla enforces naming rules via the `getName()` function in:
+**`libraries/src/MVC/Model/BaseDatabaseModel.php`**:
+```php
+if (!preg_match('/Model(.*)/i', get_class($this), $r)) {
+    throw new RuntimeException("Invalid model class name");
+}
+```
+This ensures proper MVC structure is maintained in Joomla 5.
+
+## **Conclusion**
+By adhering to Joomla’s MVC architecture and naming conventions, developers can build maintainable, extensible, and well-structured components. Keeping site and admin logic modular improves reusability and security within the Joomla ecosystem.