After reading a fair few posts on Stack, and also some material recommended to me on line, the MVC pattern is quite open to interpretation, so please don't answer with another explanation. Thanks!
I'm reaching the end of designing my own PHP MVC now, and have two possible ways to move forward with the views.
But first, my controllers are currently quite dumb, not containing any classes and simply call public methods from the suitable models, and render the appropriate view.
Views are included as necessary, so naturally the objects are available to them via the constructors, along with all the methods (inc delete/update etc).
My first option is to get data using something like this in the view
foreach($object->fetchData() as $data)
and then looping through the results. However some people do not agree with this, and have suggested that such methods should be excluded from the view. Instead it has been recommended that I assign this to a variable in the constructor, and then use this variable in the view
//constructor
$fetched_data = $object->fetchData()
// view
foreach($featched_data as $data)
I don't like this very much, as it seams messy and unnecessary.
With all my critical methods being made available to the view, could this be considered a problem?
So here's the question. Do I keep it how it is, and create new methods in the MODEL for rendering data (as above) OR can I create a class in the constructor, extend the model into it, protect the critical functions in the model, and then create my read only public methods in the CONSTRCUTOR?
Thanks!
I would create a class in the constructor. Not only would extending the model be a much safer approach, but it'd also minimize the calling of functions in the views. Am assuming you'll have several views, it's much easier to get access the constructor data than calling method functions each time in each view.
You can add classes to your controllers that will call the method functions and pass the data directly into the views, instead of clustering your constructor or bootstrap.
Related
I currently have a Helper (FieldFormatterHelper) I created to assist with consistent formatting of certain types of data (dates, booleans, enumerated types, etc) across various views.
In particular I store certain enumerated types in MySQL using an integer and then display a corresponding string value in my views. The problem I'm running into now is that while this Helper works well for my views for things like "view" and "index" Views that administrative users access from the site's backend, I also have afterSave() methods in several models that create JSON outputs for Mustache rendering on the frontend.
I understand, more or less, the core ideas of MVC and the basic arguments for, say, not trying to access a View Helper from within a Model, but I need some sort of universal access to the functionality my Helper provides. Certainly I could define my enumerated type mappings in my frontend JavaScript and other places I might need it, but that violates the DRY principle and would ultimately be a pain to maintain.
So, the question is: If it's not appropriate to access/load my Helper from within my Model, where, and how, should I encapsulate this functionality so both my Models and various Views can utilize it?
Ideally, I would be able to continue using my existing FieldFormatterHelper--perhaps modifying to be a wrapper for this new container.
Any guidance on the ways of CakePHP and MVC in general would be appreciated. Thanks.
You can implement it as a static method on a class and use it anywhere
class Utils {
static public function formatField($args) {
// your implementation
}
}
then just have your helper defer to the static method call using
Utils::formatField($args);
You can create a static function and put it in app\view\helper\AppHelper.php. Then when you want to call it you put
App::uses('AppHelper','View/Helper');
at the top of the file and call it like this:
AppHelper::staticFunction()
I have read a lot of SO topics about this already, but still haven't found (or have been able to create) a proper answer.
I am working on a small MVC framework and I want some global class/object that I can call from my controllers (but maybe models too).
There are a couple of routes I can take:
Global variable
Static class/Registry
Dependency injection
The internet seems to agree that the DI is the best route to take. I think I have grasped the idea, but am not comfortable yet. So I want to throw in some background information; I will probably be the only one working on the project, it is a small project, all my controllers extend the main Controller (so I could just load one library like class there).
As a concrete example, I want to have an array of categories. So I started out with putting that array in the CategoryController. But now I noticed I kinda want to use that array in my frontview and in ProductController as well. Obviously I don't want to load all of CategoryController into ProductController.
You could also say I could put that array in some kind of configuration or settings file, because of the simpleness of this example, but that's why it's an example. I will probably expand on it with more functionality.
So to summarize: In PHP (specifically inside a MVC model) how can you give your classes (mainly Controllers) access to some kind of common class or other sharable functionality.
Your controllers are created by "something" (usually a front controller). So when the controller is created, you could inject a dependency injection container.
And in your configuration/bootstrap (before the controller is created), you should add you categories to the container.
That way you can access the categories from every controller.
Please note that this is a simple example that doesn't totally fit the spirit of dependency injection. The best solution would be to inject directly the categories (instead of injecting the container). But that can become a lot of work if you generalize that pattern (lots of dependencies to handle in your front controller).
A solution would be to use a dependency injection framework that could do that for you.
For example I work on a DI container that lets you inject stuff with annotations (PHP-DI), but there are several other libraries for DI so you have a choice.
My 2 cents:
In a small self-made mini-framework I have done some time ago, I have created a global singleton class named Application, and anything/everything which should be accessible from anywhere/everywhere was a property or method of this class.
In my case, there was a $db property for database access, a $user property to access the user data and methods, an $input property for a "powered" $_REQUEST access, and so on.
Of course, you have many other options, suitable for different scenarios. This approach simply worked fine for me on that occasion.
Now, if you want to access a controller from another controller, this really sounds strange. This "thing" that you want to access should be a model class, a library class, or anything else, but it should not be "locked" inside a controller class. Indeed, the controller should be "as thin as possible", and focus on calling the appropriated methods from other classes, based on the user input (request) and then calling some output method to generate and send the answer (response).
Finally, although I've read some criticism and complaints about it (as well as praises too), I do make use of static methods a lot, mainly for classes which are more "helpers" than anything else.
I've noticed that all my models look very similar. Most of them tend to follow a pattern where they are collections of methods containing active record code that are just slight variations on one another. Here is an example:
class Site extends CI_Model {
public function get_site_by_id($id)
{
// Active record code to get site by id
}
public function get_sites_by_user_id($user_id)
{
// ...
}
// ...
public function get_site_by_user_id_and_url_string($user_id, $url_string)
{
// ...
}
// Non active record methods and business logic
// ...
}
This approach has worked fine for me but I'm wondering if there is a more elegant solution. It just doesn't seem right to me that I should have to create a new method every time I need to look up data in a new way. Is this common practice or am I missing a way to refactor this?
Strictly following your request, you could add an intermediate class between the main model class (CI_Model) and your class (Site), something like
class MyCommonMethodsClass extends CI_Model {
}
and you would extend it in your classes (Site), while putting the common code on it. That would work and could be somehow'elegant'. In fact at the end you would end up adding your basic crud, site adapted actions, to it.
Now, if that's 'clean', that's another thing. Again, strictly speaking the model does that. It takes care of common and 'advanced' getters. And yes, they almost always have the tendency to have the same code all around your website. The problem is that, although that looks nice in your code (less code) you're technically sacrificing abstraction between your business logic and the db. Are you a model purist or practical one ?
I think this is matter of opinion but I think best practice is to create some sort of Create, Retrieve, Update, Delete (CRUD) model which does many basic SQL functions like GetID, UpdateByID, GetById and so on.
CRUD models can only go so far in helping you with more modular queries. But it makes sense to call a function called GetId and pass it some parameters than to have different functions for each table.
As I say though, CRUD's can only go so far. For example it would make sense to have a function that queries a database users table to check if a user has verified and username & password match. As this is a unique and not an abstract function, it should have it's own function defined.
Also as a best practice, Logic and Database access should never be mixed in the same file.
It is common practice to have different methods to handle getting your data like that. The Single Responsibility Principal states that every object should only do one thing, by making multiple methods that get very specific data you are creating very maintainable and easy to debug code.
If you have multiple classes that are providing essentially the same functionality, then this would suggest that there may be something wrong with your class hierarchy (a so-called "code smell"). If they have similar interactions then that suggests that they are related in some way. If that's the case then the chances are they should all be inheriting from a common superclass that implements the functionality common to all your subclasses, with each subclass simply specializing the generalized functionality of the superclass.
The advantages of this approach are:
You're not repeating work (SPOT, DRY)
Code that interacts with the classes can be written in a more general way and can handle any object that inherits from the superclass (substitution)
I do not think there is any thing wrong with creating an 'base' model class to extend you other models by. If it is solid and well tested, it can make you life easier. What is the point of creating the same CRUD functions over and over again?
Another benefit of doing it is that you can have a base development repository that you clone to start all new projects.
If you need an example of how to do this then look at a question I previously asked.
You can also do the same with your controllers.
I’m fairly new to CodeIgniter and have a question. I’m a bit confused about Classes, Libraries and Objects.
Does CodeIgniter replace the normal PHP way of usings objects i.e. $var = new car(); with libraries i.e. $this->load->library('some_library'); $this->some_library->some_function(); ?
If both are valid, is there a difference? If so, what are the differences and when do I use one over the other? Which is more common/proper?
I am asking because I created a class, but I'm not certain what is the correct manner in which to instantiate it.
Thanks in advance
I am not familiar with CodeIgnitier. But familiar with other PHP frameworks. Most of frameworks use this way for performance improvements, registering things, executing certain events, and making things simpler for developer...
For example if you want to create class "car" with is somewhere in library directory you would have to include the file first before you can create object of that class (miltiple lines of code, more room for error). The framework will create the class and includes related files in 1 line of code (easier and safer).
Framework way also works as a factory. Instead of recreating an object, it will create object only once and every time you call the method again it will return the reference to existing object.
More things are happening behind the scenes when you use framework. Things are getting registered, etc...
CI doesn't replace class behavior per se, it simply adds functionality that allows access to custom libraries/models/views as singleton objects via the core object for simplicity.
Nothing is stopping you from creating (as I have in one of my projects) additional files with classes for non-singleton entities and require them in a model for further use. On hindsight, I should probably have used helpers for this.
What the loader ($this->load) class does, among other things, is it creates a single object of the specified class (model, library or view - not helpers though, see below) and attaches it as a property of the core class that is normally accessible via $this.
Helpers are a bit different. They are not attached, but instead simply 'read' into the global namespace from the point where they are loaded.
To answer your question, it would be more proper to use the loader class in instances where you don't need more than one instance of a class created. If you need 'entity' classes, your best CI-compliant bet would be to create them as helpers.
Given only this context, this looks like Inversion of Control (maybe I'm wrong, I haven't looked too closely at CodeIgniter).
You don't want to rely on the type car as in new car(). What if later you want to make $var a racecar? $var can still do the same things, but it is forced to be a car because you constructed it directly. Or what if you are testing this class, but car is some complex object which calls some external service. You want to test your logic, but don't care if the car service isn't working. So you should be able to change $var to actually load a mockcar. You can't do that if you do $var = new car().
What is Inversion of Control?
Ok, it's my fault. I've never ever learned programming at a school and that's why i'm always ending up in a spaghetti code. I've always curious about different patterns and tried to understand them at least in a basic level.
MVC is my worst fear and i think i'll be never able to use it's advantages because of i don't understand it's fundamentals.
My actual question/problem looks like:
The front controller calls a 'Core' class which is doing some initialization then it calls the actual controller with the correct action/parameters. The controllers always extending the 'Core' class so i can acces it's variables, etc. They're working nicely together but here comes my real problem.
Some kind of methods (getting a database entry in most of the cases) are required in different cases. (e.g. a product needs it's manufacturer)
In this scenario i have two (bad) choices:
Inject the required method into the 'Core' class so it's getting bloated over time
Inject the required method into the actually called controller so i will end up a redundant codebase
I see a lot of possible problems in my approach:
Controllers are always extending 'Core' class
'Core' controller holds the database object so without it i cannot access my Db
Database functions (e.g. getting a product) are in the controllers but i cannot access them because they're always calling 'Core' first (extending problem again)
Please tell me:
Where is the biggest problem in my approach and where can i correct it?
Note:
Please don't treat this as a general question, i think this is an answerable thing. If you need some clarification, please ask for it and i'll try to lighten up things.
Thanks for your precious time, fabrik
Your data is represented to your Controller and View through the Model. The Model may be supported by a Repository but depending on the overhead you might want to provide your database access in your Model. The data architecture should be similar to this:
(Repository<===>)Model<===>Controller--->View
Your biggest problem is having the "Core" class, get rid of it asap.
By the way, the FrontController is not the only way to do things MVC things either.
Your second problem is that controller deals with database, it shouldn't. I suggest you use some abstract data layer, which you use only in your models. And controller should deal only with models, it shouldn't care how models get their data persisted and fetched.
Look into using a DI framework to automatically inject an instance of a repository into your controllers (or even better, a proxy class). Try to keep business logic outside of your controllers, but rather, refector it out into a helper or proxy class.
I tend to split my logic up into views => controllers (just for interaction between business later and view) => business logic => models (DTOs) => low-level data access at a minimum.
Also, if you need common helper functionality in your views, perhaps create several extensions to help.