Structuring classes and objects in CodeIgniter for future upgrades? - php

Question

I'm new to Codeigniter and pretty new to OOP as of the last month or so. I've been playing around and have been trying to make a blog page with a list of 10 posts and have different functions and possibilities for each.
For example, in the future I want to be able to show different buttons below posts depending on whether they are a logged in user, or if they are the post creator, etc.
Would I be best off making a new class 'blog_posts' and making an instance of it for every post I show on the page? like:
$this->load->library('blog_posts'); // in library or models, I'm not too sure?
$new_inst = new blog_posts;
$new_inst->show_post();
My end goal is to get it all as easily updated, changed, or modified in future if needed, I've seen simple tutorials online:
http://blog.pisyek.com/2011/03/create-a-simple-blog-using-codeigniter-2-0-part-1/
But I can't see them being easily updated and modified in future. I haven't seen a lot of other CI apps using new instances of classes, so I'm thinking there may be a different way in CI? Are new instances used in CI a lot?

Answer 1

Start with the controller. With Codeigniter -- anything you can do in a model, you can do in the controller. The easiest way to start -- just put your methods in the controller and set up a simple view file.
Always do a simple sanity check to make sure the basics are proper. Set up a controller and echo out some text.
In the controller try:
Get blog posts from your database using active record commands
Pass the blog posts result to $Data
With each step, Echo out something in the controller to confirm that its working
Next -- try using $Data to pass the blog results to the view.
After its working and you understand the basics -- then start pushing your methods to a Model. As you refactor and clean, your controller will get 'thinner'.
typically for blog posts you would have one model, that would return the blog posts and might also have your insert / update / delete methods. i say might because it usually makes more sense to have a public blog controller, that just shows blog posts. and then a separate blog admin controller -- that is only available to users who are logged in.
These two controllers - can share the same blog model. So for example to show blog posts on an admin screen - you could use the same method as showing the posts on a public page. Whereas you might have an admin blog model -- which has the create / update / delete methods.
That way you enforce a very clear separation of User Roles from the start -- people who are viewing the public blog should not be able to delete posts. The public show blog class is not "responsible" for editing.
This is something that i'm grappling with -- like the normal way to demonstrate a blog is to have all the methods together. Which makes sense in terms of "what can we do with a blog post" -- but it doesn't make any sense in terms of user roles.
ok Next - work on your create and update and delete methods.
Next try creating your log in methods. Make the Login process separate controller / model / view.
Eventually you could have one method call in the constructor of your blog admin class that checks to make sure that the user is logged in - otherwise it redirects them to a login page. That way you dont have to check over and over again in the view files etc to make sure they are authorized.
( highly recommend the free codeigniter tutorial series on net tuts website )
more rambling:
looking at the process from the point of view of the actor (user,role) -- for me helps to clarify what the chain of control should be. really critical roles - like an admin that has the power to delete all blog posts - the system should know that role at the top of the class.
best 'worst example' is when there are "is this a super admin?" checks in the view code. the view should not know anything about admin roles. BUT MUCH WORSE when you put a reference to an admin role in some view file -- what happens when you want to change that admin role in some way? now you have to go into all your view files!
class and method names - i'm moving towards not revealing any business or crud or field or any other type of business information in the URL. no nouns no verbs no ids. as simple as possible, with very few public url 'doors' into the app.
whats wonderful is that codeigniter makes it really easy to make your methods private. for critical pages: only use the public index method in the class for redirecting and make all other methods private.
use routes that directly to private methods. or public methods with broad names, that if successful -- like you have confirmed their credentials - go to private methods in the class like $this->_showAdminPage()
this is where defining a role like - blog editor - makes things very clear from a functionality point of view, AND keeps the valuable business knowledge private.