Okay, I'm learning all about MVC, Bootstrap, Ajax and Smarty and I understand the basic principles of MVC. I am having one major issue however and I just cannot wrap my head around it, no matter how much I try and no matter how much reading I do.
At it's very core the thing I cannot seem to get my head around is how to pass variables from view to controller from controller to view.
If I want to assign a variable, I can simply $view->assign('variableName', 'variableValue') No issues there, then in the view if I want to call it, it's as simple as $variableName and it's in the view.
My issue is, I want to be able to minipulate data, for example let's say I want to have a list of items, numbers for the example, a list of 1-10, the user chooses 6, I want a way to be able to "POST" that back to the controller without actually having use POST/GET, I want to be able to essentially let it call an Ajax to send the users selection but I do not know the best way to do so.
If I was doing this without MVC, or Smarty it would be as simple as form, action post, I know that but unfortunately that isnt something I can use in this instance.
Any help you can offer would be appreciated.
I will begin with the normal workflow, e.g. without the MVC approach.
Let's say, in a certain moment you are seeing a web page in the browser and let's call it MAIN PAGE.
When you are submitting a form from main page without using ajax,
the whole page refreshes, no matter if the form action points to the
main page or to another one.
When you are submitting values using an ajax call (as part of the
main page code), then the main page will not be reloaded. E.g. an
ajax call targets ANOTHER PAGE to fetch some data in some format
(html, json, etc) and prints the data on screen, in a specified
container inside the main page.
Now, let's see what happens in a web MVC architecture.
You must understand, that an MVC application consists of only one page: index.php. This page serves as the MAIN PAGE, but ALSO as the ANOTHER PAGE, targeted when using ajax calls. The index.php page is therefore processed each time when you are sending a request to the web server - be it through manually changing the url in the address bar of the browser, through posting a html form, or through starting an ajax script.
All other components of the MVC structure (classes, template files, etc) are serving only one purpose: to build the structure of the index.php page - as main page or as ajax response page.
So, in principle, in the index.php page you'll have something like this:
Read the URL, e.g the url components: controller name, action name, action parameters (HTTP GET query string). For this you can use an instance of a Router class.
Create an object of type Request, passing and saving the url components into it. Here are read and saved the other server request variables too, e.g. HTTP POST, HTTP cookies, etc.
Create an instance of the View class.
Based on the url's controller name instantiate the corresponding Controller class, passing the Request object and the View instance to it. Here you'd give the model layer constructs (like a model factory object) as constructor parameter(s) too.
Based on the url's action name call the corresponding controller method, e.g. the controller "action". Exactly here, inside the controller action, are taking place the processing of the server request variables (saved in the Request object), the loading of the template files and their rendering, including transferring the processed server request variables into them.
In the last step, the rendered template files will be directly printed or further passed to an object of type Response, which in turn prints them.
In the end, you'll have a fully "constructed" index.php page, which will be either printed on screen by the browser (if index.php has the role of a main page) or processed by the browser as the result of an ajax request.
Note that I used the description of the steps found in the classical MVC approach. There are also other... types of this concept, best presented in Architecture more suitable for web apps than MVC?
Other very good resources:
MVC for advanced PHP developers (contains a list of great resources)
How should a model be structured in MVC?
Understanding MVC Views in PHP
Understanding MVC
MVC (Model-View-Controller) in PHP tutorial (Part I...IV)
Model-View-Confusion (Part I+II)
James Mallison - Dependency Injection and Dependency Inversion in PHP
Good luck.
I just started to use codeigniter. I need to know the explanation of
Views are never called directly.
Is it mean that i can not use $this->load->view('My_view') into another view?
I created a project in core php and decided to convert into codeigniter. In my project a page has different section so i created a main file recipes.php in views. I also created a folder where i put different section files to include in recipes.php. In my controller i loaded recipe view, it showed the recipe page then inside recipes view i used $this->load->('categorymenu'). It worked fine. I didnt pass any data since this section contains simple html. But im confused that it is not a right way of loading views.
So please can someone explain in detail. Am i doing the right thing or is there another way of doing it.
I also loaded the view in controller and passed to main view in controller which also worked perfect. But as i mentioned im not sure which is the right approach. My apology if this is a stupid question.
As you are naive to Codeigniter no question asked by you is stupid.
Now the answer of your question is that,
You can load a view inside another view and it is absolutely acceptable as there will be some cases when you have to put header in all pages of the web site, that time you have to load the view in another view.
Second is that the correct way to load the view is in the controller. As the controller is the mediator between the model and view. if you want some data of database to be displayed in your page you have to get that data through the function created in the model and then after you can load the view in controller and can pass the data in that.
This is code of controller
public function temp()
{
$data['recs']=$this->my_model->my_function(); //getting data to pass in view
$this->load->view('my_view',$data); //load the view
}
I have code that I want to run on every page load, such as looking up menu items, looking up the users details etc. These will be displayed on partial views that make up the main view.
Where do I place this code so that it can fill my partial views with each page load? I know I can just add the code to the top of the partial view itself, but this doesn't really follow the MVC pattern.
Is there a function that is always called that I can hook into in my base controller?
You can create a base viewmodel for the repeated code and make other viewmodels inherit from it.
...such as looking up menu items, looking up the users details etc
You're a bit unclear about the type of information you want to load: in case the info is a view-component then indeed you should create a base-view and inherit from it or include it (composition) in any other view.
But, in case it is "user-information" - the data should live in a model-component that again, may live as "base-model" object that is included in other model components.
I have a blade template called 'main' and I wonder how I can render a sub template by calling a controllers method in my main template. Lets say I have a Controller WidgetsController with a method getSubView. The method returns a specific view with some data from (for instance) a database.
I already tried to #include a template but this will not call the controller which sets some necessary data to the view.
Thanks.
views don't call services, they only take variables and put them on screen for presentation.
you're on the good side with #include(). you only need to gather the infos for that sub view beforehand in the controller, and pass it to the View::make('main')->with($vars).
you may also consider using another <?= View::make('subview')->with($vars->sub);?> within the the view. or just use the #extend functionality.
I don't entirely understand your question.
I think what you are looking for is a View Composer
It allows you to get data for a subview without having to create the data in every controller.
I have an application that when accessed its the main.php controller, which spits out the main_view.php view. Now I was wondering what is the right way to go from this view to another controller to generate the next view. The CI tutorials just talk about going from controller to view not the other way around. I have a form that I need to submit on main_view.php and then generate the next view from a database based on that info.
thnks!
You target controllers and functions in the url like this yoursite.com/controller_name/function_name. so the form on main_view.php can link to any controller/function you want, ie yoursite.com/form_controller/form_processing_function
Use site_url to ensure portability of your application:
echo site_url("controller/method");
See http://ellislab.com/codeigniter/user-guide/general/helpers.html for more info.
Read this chapter in the user guide:
http://codeigniter.com/user_guide/libraries/form_validation.html