For a forum-like website that I'm building, I have PHP classes 'user' and 'post'. A user has an array of posts. How to resemble that connection in a relational database? With a foreign key on 'post', pointing to a 'user'? This makes sense to me because of a one-to-one relationship, whereas 'user' to 'post' would be one-to-many, and so far as I can see. Any thoughts are welcome - thanks!
Your solution is good. I can't see any better option.
Just for clarify;
Now, with OOP, the goal is to work with objects.
So first step is to create object from database. If you want to go further, you can use an ORM and create your DAO. With this layer, you can manipulate object, modify them and finally save them into database with OOP approach. An exemple, Doctrine2 : Doctrine website
Now, for simple projet you do not absolutely need ORM. Just take care to work with object, and, for exemple, create little method in your object: save(...) who Insert in DB your object.
Complexify it by adding update, delete,... and finally go on CRUD system.
I think it's good idea before go directly on ORM, and see you to learn and concept good OO project.
Hope it's will help you (and sorry for my very bad english :) )
Related
I'm learning Laravel and I'm watching many tutorials, but I dont really get it, what's the difference between the controller and model, because you can put in both a function.
Controllers in Laravel are used to determine how to handle http requests.
When you have anything to do with the DB, its better to place those function in the model, and call them from the controller.
In clear terms:
Model performs all operations on data from DB.
Controller call necessary model methods and ready the data.
View take care of displaying the data.
I hope this is clear enough.
You will be familiar with all of this soon.
model methods is for relationships mainly , or to make some thing for every object of this model (database table) every column in db is an object and every table is a model.
but in controller you set your app functionality that you want , and its an intermediator between model and view .
i hop this makes you good in this point.
good luck
You can write functions anywhere, you are perfectly right.
But is not an efficient way to do things.
The answers for those questions can be easily find out. Search about MVC pattern. In few words, remember brief:
MODEL => working with relational databases / storing the data
CONTROLLER => working with the logic(taking inputs, calculus etc) / general functionalities
Combining them is more efficient than working with those together, that is the reason why using a pattern is more great than writing code in a old style mode reinventing the wheel again.
I was given this project to work on with absolutely no documentation or contact developer. I noticed in the database dump that they are storing what looks like PHP Namespaces for Eloquent models in a couple tables. For example an address table has a string column named "object_type" with the value always being "App\Entities\Client". I searched through the whole project for the PHP code that would use this value. Hopefully to give me insight to it's purpose. Not to my surprise, the project never uses this value. I just see it hard-coding these values upon insert into the DB.
My question is, is this some sort of Database and/or ORM modeling design practice? If so, could you explain how this could be used in a simple practical sense?
Maybe this was some concept the developer had and it never evolved. It's interesting idea but, the idea of joining through MySQL on a string conditional sounds like torture.
Sounds like Laravel polymorphic relationships:
Custom Polymorphic Types.
By default, Laravel will use the fully qualified class name to store the type of the related model.
And, yes, this is a valid modeling technique, though purists rightly argue this technique abuses normal form.
I am not sure what the developers where thinking.
But imagining we are in a forum with thread and replies to each thread. We maybe want to have a Favourites table where we can save replies and threads.
A way to do it would be to have a column in the favourites table called "object_type" (just to use the same term you have in your case) and then when we save an object into the database with eloquent we can use:
$favourite->object_type = get_class($thread); //or get_class($reply) in case we want a reply
$favourite->save();
This way will save the namespace of that class into the database. But laravel will recognise it when we get it from the database.
Hope this cold be helpful.
Hey Guys
I know Stackoverflow is may not the right place to ask, if there's another Stackexchange group where
this question fits better, then please tell me.
So, I'm trying to learn OOP. I think I understand it quite good, but there's one thing I really can't figure
out what the right way is, and thats the handling of database.
So, I'm confused a bit of what should go in which class.
Lets say I've a db class. Inside of this class I'm connecting to the database in a constructor. And now lets say
I've got a user class.
So now the question:
Where should I put in the query for example creating a new user? Should i create a method in the user class,
or should I create a method in the DB class? If in DB class, should it really be a method like create_user()
or should it more be something globally like query where I can pass in whatever query I want.
Here, for example a project from Github:
https://github.com/christran/PHP-OOP-Login-Register-System/blob/master/classes/user.php
As you can see, all query methods are in db.php and from user.php he's just calling this methods. So is this the right way to go?
Or doesn't it matter at all? May, any of those approches is "more" OOP than the other?
It's actually just really confusing me and I don't understand whats the better way. I've searched a lot, but never
found an article to this specific question.
So what I did, I looked for projects on Github and looked at their code, how they've solved the problem...
But with this method I just got confused even more, because you see both.
Is it just a preference of the coder?
I am really thankful for all your help. Have a nice day! :)
Here a little example of what I mean:
Query inside user class:
class user {
private function createUser() {
//SQL Query here (prepared statements etc...)
}
}
OR:
class user {
private function createUser() {
// Call to db.class to insert_method() ...
}
}
Basically, you are looking into ORM.
To answer your question specifically,
Should i create a method in the user class
This is possible, and is called Active record pattern, where an entity contains not only methods related to itself (like $user->getBirthday()) but also methods that related to database interaction (like $user->save()).
or should I create a method in the DB class?
This is impossible, as this class will become enormously big.
However, you can create a sister class for the every entity, that will be responsible for the database interaction. This approach is called Data Mapper pattern. For example, there is a User class that contains methods related to the user, and also a UserMapper class, that is inherited from abstract mapper class with generic methods $userMapper->save(), $userMapper->find() and such.
The createUser method that contains the query shouldn't be part of the User object, but neither of the database object. The first one is for business logic. The latter one is for managing the database method and providing generic functionality for executing statements. A different object inbetween those objects should be the one that takes the data from the user object and generate the queries for storing it in the database.
The term I think you're looking for here is ORM (Object-relational mapping).
This concept is about mapping objects to a different, incompatible structure, like a database.
There are ORM libraries/frameworks available for PHP which can do much of the work for you, and some of them are part of, or can be used with, popular MVC frameworks like Eloquent ORM in Laravel. For example, they will often provide the basic CRUD operations by implementing the SQL statements needed after you just configure the right database table.
In terms of OOP, you will often have an extra layer on top of it. So you got a business object User, which contains the rules for users, for instance rules it has to follow for a user name. The business object will enforce those rules and contain the general behaviour of a User object. For saving you make use of an ORM to save a user object to a specific database. The database logic is not in the User object itself. It shouldn't have to know about the specific queries to save itself, and maybe it shouldn't even be aware of concepts like loading and saving. It just contains logic and data, and other parts of the implementation are responsible for persisting that data (optionally using an ORM framework to make things easier).
I know that ORM and redis is weird enough but. My redis server is a storage (not temporary). So I discovered some queries and commands but now I want to know how to use it in best way. As everybody know ORM is good enough (ActiveRecord, Doctrine2, etc.). So give me your thoughts how to create model and use it with redis db.
My thoughts is to create some abstract class that will load (predis) and work with it BUT I have no idea how to make checker\manager of 'columns' (yes I know that redis has not such things as columns), simple example, we call this one
hset('user:id_111', 'username'. 'admin')
hset('user:id_111', 'password'. 'pass')
hset('user:id_111', 'email'. 'some#mail.com')
hset('user:id_111', 'confirmed'. '1')
After that we should have model that will return all method we need (they will be writted manually)
$oModel->getUserName();
$oModel->getPassword();
$oModel->getEmail();
$oModel->getConfirmed();
So now question is of calling queries, basically in abstract model we should create Predis\Client() but hey, it will be created in EACH model (is it bad?)!
Also do we have check ALL vars\values when changing data in model, simple example what should we do on incorrect data? Exception or simply not saving model and save error in model?
Any ideas\thoughts you have, please share.
PS: no need code, enough will be description how you see this one
I recently needed to tackle the same problem; I started building an orm for redis. It's still early in development, but might help you out https://github.com/tystr/redis-orm.
Now that I have read an awfull lot of posts, articles, questions and answers on OOP, MVC and design patterns, I still have questions on what is the best way to build what i want to build.
My little framework is build in an MVC fashion. It uses smarty as the viewer and I have a class set up as the controller that is called from the url.
Now where I think I get lost is in the model part. I might be mixing models and classes/objects to much (or to little).
Anyway an example. When the aim is to get a list of users that reside in my database:
the application is called by e.g. "users/list" The controller then runs the function list, that opens an instance of a class "user" and requests that class to retrieve a list from the table. once returned to the controller, the controller pushes it to the viewer by assigning the result set (an array) to the template and setting the template.
The user would then click on a line in the table that would tell the controler to start "user/edit" for example - which would in return create a form and fill that with the user data for me to edit.
so far so good.
right now i have all of that combined in one user class - so that class would have a function create, getMeAListOfUsers, update etc and properties like hairType and noseSize.
But proper oop design would want me to seperate "user" (with properties like, login name, big nose, curly hair) from "getme a list of users" what would feel more like a "user manager class".
If I would implement a user manager class, how should that look like then? should it be an object (can't really compare it to a real world thing) or should it be an class with just public functions so that it more or less looks like a set of functions.
Should it return an array of found records (like: array([0]=>array("firstname"=>"dirk", "lastname"=>"diggler")) or should it return an array of objects.
All of that is still a bit confusing to me, and I wonder if anyone can give me a little insight on how to do approach this the best way.
The level of abstraction you need for your processing and data (Business Logic) depends on your needs. For example for an application with Transaction Scripts (which probably is the case with your design), the class you describe that fetches and updates the data from the database sounds valid to me.
You can generalize things a bit more by using a Table Data Gateway, Row Data Gateway or Active Record even.
If you get the feeling that you then duplicate a lot of code in your transaction scripts, you might want to create your own Domain Model with a Data Mapper. However, I would not just blindly do this from the beginning because this needs much more code to get started. Also it's not wise to write a Data Mapper on your own but to use an existing component for that. Doctrine is such a component in PHP.
Another existing ORM (Object Relational Mapper) component is Propel which provides Active Records.
If you're just looking for a quick way to query your database, you might find NotORM inspiring.
You can find the Patterns listed in italics in
http://martinfowler.com/eaaCatalog/index.html
which lists all patterns in the book Patterns of Enterprise Application Architecture.
I'm not an expert at this but have recently done pretty much exactly the same thing. The way I set it up is that I have one class for several rows (Users) and one class for one row (User). The "several rows class" is basically just a collection of (static) functions and they are used to retrieve row(s) from a table, like so:
$fiveLatestUsers = Users::getByDate(5);
And that returns an array of User objects. Each User object then has methods for retrieving the fields in the table (like $user->getUsername() or $user->getEmail() etc). I used to just return an associative array but then you run into occasions where you want to modify the data before it is returned and that's where having a class with methods for each field makes a lot of sense.
Edit: The User object also have methods for updating and deleting the current row;
$user->setUsername('Gandalf');
$user->save();
$user->delete();
Another alternative to Doctrine and Propel is PHP Activerecords.
Doctrine and Propel are really mighty beasts. If you are doing a smaller project, I think you are better off with something lighter.
Also, when talking about third-party solutions there are a lot of MVC frameworks for PHP like: Kohana, Codeigniter, CakePHP, Zend (of course)...
All of them have their own ORM implementations, usually lighter alternatives.
For Kohana framework there is also Auto modeler which is supposedly very lightweight.
Personally I'm using Doctrine, but its a huge project. If I was doing something smaller I'd sooner go with a lighter alternative.