Databases
StackOverflow2013
Postsdbo
POHow to build a PHP Dependency Injection Container
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POHow to build a PHP Dependency Injection Container
    primarykey
    data
    text
    <p>I've recently learned about the advantages of using Dependency Injection (DI) in my PHP application. However, I'm still unsure how to create my container for the dependencies, or whether I should be using DI at all for the online forum that I'm building.</p> <p>The following code is my version of the DI container I have made based on the example I learned from <a href="http://net.tutsplus.com/tutorials/php/dependency-injection-huh/">here</a> .</p> <pre><code>class ioc { var $db; var $session; var $user_id; static function newUser(static::$db, static::$user_id) { $user = new User($db, $user_id); return $user; } static function newLogin(static::$db, static::$session) { $login = new Login($db, $session); return $login; } } $user = ioc::newUser(); $login = ioc::newLogin(); </code></pre> <p>I have a few questions: </p> <p>1) Where should I instantiate my injected dependencies, such as $database, $session, etc? Would it be outside the container class, or inside the container's constructor. </p> <p>2) What if I need to create a multiple instances of the User class inside other classes? I can't inject the previously instantiated $user object because that instance is already being used. However, creating the multiple User instances inside of another class would violate the rules of DI. For example:</p> <pre><code>class Users { function __construct($db, $user_id) { $this-&gt;db = $db; $this-&gt;user_id = $user_id; } function create_friends_list() { $st = $this-&gt;$db-&gt;prepare("SELECT user_id FROM friends WHERE user_id = $this-&gt;user_id"); $st-&gt;execute(); while($row = $st-&gt;fetch()) { $friend = ioc::newUser($row['user_id']); $friend-&gt;get_user_name(); $friend-&gt;get_profile_picture(); } } } </code></pre> <p>3) I'm wondering if I should even adopt DI, knowing that I have to rewrite all of my previous code. I've previously been relying on global variables that I instantiate in my initialize.php, which is included in all my files. </p> <p>It seems to me that DI creates a lot of overhead and there are situations where it is unusable (as in my #2 example). The following site is from a developer who cites many good reasons not to use DI. Does his arguments have any merit? Or am I just using DI wrong? <a href="http://www.tonymarston.net/php-mysql/dependency-injection-is-evil.html">check this link</a>.</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USAnonymous
    1. USAnonymous
    plurals
    1. PL
      singulars
      1. LTLinked
    2. PL
      singulars
      1. LTLinked
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PO
      singulars
      1. PTAnswer
    2. PO
      singulars
      1. PTAnswer
    3. PO
      singulars
      1. PTAnswer
    1. VO
      singulars
      1. POHow to build a PHP Dependency Injection Container
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. POHow to build a PHP Dependency Injection Container
      1. This table or related slice is empty.
      1. VTApproveEditSuggestion
    3. VO
      singulars
      1. POHow to build a PHP Dependency Injection Container
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI've read that website a couple of times, mainly out of a fascination about how consistently angry the author is. Apparently his freedom of speech extends to insulting people on their own blogs, and the people who delete him are Nazis. Oh dear... `:)`
      singulars
      1. POHow to build a PHP Dependency Injection Container
      1. UShalfer
    2. COTo answer the question a bit more directly (!), Symfony2 has a [standalone DI component](http://symfony.com/doc/current/components/dependency_injection/index.html), which you may find worth looking at.
      singulars
      1. POHow to build a PHP Dependency Injection Container
      1. UShalfer
    3. COcheck out http://docs.codehaus.org/display/PICO/IoC+Types for some information on various approaches.
      singulars
      1. POHow to build a PHP Dependency Injection Container
      1. USGordon
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload