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Question

I'm trying to learn MVC design pattern for web applications so I decided to write my own PHP MVC framework. Before writing this post I read a lot of tutorials and forums about MVC. Now I pretty well understanding the MVC idea, and how communicate controller-model-view. I have write router and few modules (login, categories, ...) - seems it's working.
Now I'm confused a bit:
If I call localhost/LogIn I get only login form, if I call localhost/categories I get category list. Everything OK, but I want to create index controller and when calling localhost/index I want see login form, categories and a lot more modules.
Should I call controllers (login, categories) from indexController.php?
I need advice how to concatenate needed modules in one page.

Answer 1

No, controllers shouldn't be calling each other's functions. Some frameworks introduce "helpers" to implement what you need.
Controllers can use the same models, and views anyway are going to be different, so you can use your Categories model to provide you categories to display (e.g. $categories->getCategoriesList()) and then using it in category controller view and also in index controller view.
A legitimate method of calling one controller from another is by forming an HTTP request - e.g. receiving an HTML snippet (another controller rendered view) to display in your view via AJAX or using an iframe with a source pointing to your another controller (which is a clumsy solution, mostly for idea illustration).

Answer 2

You need several things:
You need a .htaccess file that will cause all requests to go through your index file, here is a simple one:
RewriteEngine On
RewriteBase /demo
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-l
RewriteRule ^(.+)$ index.php?url=$1 [QSA,L]
In the index.php file you need to set the include path, so you won't have to explicitly include the modules/controllers/views or any other class you choose:
define("APPLICATION_PATH", realpath('.'));
$paths = array(
APPLICATION_PATH.'/controllers',
APPLICATION_PATH.'/models',
APPLICATION_PATH.'/views',
APPLICATION_PATH.'/libs',
APPLICATION_PATH.'/includes',
get_include_path()
);
set_include_path(implode(PATH_SEPARATOR, $paths));
now add the 'magic method' for autoloading classes (called automatically) and initialize your Bootsrap class:
function __autoload($className){
$fileName = str_replace('\\','/', $className);
require_once "$fileName.php";
}
new Bootstrap();
Bootstrap.php:
<?php
class Bootstrap {
public function __construct() {
$url = $_GET['url'];
$params = explode('/', $url);
//if controller exist - call it, else call login controller
if (isset($params[0]) && $params[0]){
$controller = new $params[0]();
}
else{
$controller = new login();
}
//if method exist - call it, else call index method
if (isset($params[1]) && $params[1]){
//if parameter exit - call method with param, else call witout param
if (isset($params[2]) && $params[2]){
$controller->$params[1]($params[2]);
}
else{
$controller->$params[1]();
}
}
else{
$controller->index();
}
}
}
That should give you a basic MVC Framework.

Answer 3

Use your controller (index.php) to centralized code that would be used on every page (request validators, error handles, exception handlers, session stuff).
Create a Router class to get the correct models. Allow the models to get the correct views. I have included some UML diagrams from my other answer (https://stackoverflow.com/questions/42172228/is-this-how-an-mvc-router-class-typically-works) to help out. Remember, try to program to an abstract interface, not to a concrete implementation.