How to use ORM (Object Relational Mapping) in Kohana framework?

Kohana is a lightweight PHP framework developed using the MVC architectural style. It provides ORM (Object Relational Mapping) to simplify database operations and improve development efficiency. In this article, we will explore how to use ORM with Kohana framework.

1. Configuring the database connection

First, to use the ORM in the Kohana framework, we need to configure the database connection in the configuration file. Open the /application/config/database.php file, modify the mysql array, and fill in the correct database host, user name, password and database name.

For example:

return array(
   'default' => array(
       'type'       => 'MySQLi',
       'connection' => array(
           'hostname'   => 'localhost',
           'database'   => 'mydatabase',
           'username'   => 'myusername',
           'password'   => 'mypassword',
           'persistent' => false,
       ),
       'table_prefix' => '',
       'charset'      => 'utf8',
       'caching'      => false,
       'profiling'    => true,
   ),
);

2. Define the ORM model

The ORM model is a PHP class that represents a database table. We need to create a new file in the /application/classes/Model directory to define the ORM model. The name of this file should be associated with the table name and end with the _Model suffix.

For example, if we want to create an ORM model that represents an article, we need to create a file named article_Model.php in the /application/classes/Model directory.

The following is an example of an ORM model:

<?php defined('SYSPATH') or die('No direct script access.');

class Model_Article extends ORM {

    protected $_table_name = 'articles';

    protected $_primary_key = 'id';

}

In the above example, the ORM model Model_Article inherits the ORM class, indicating that its functions are provided by the ORM class. The protected $_table_name variable specifies the name of the data table represented by the ORM model, and the protected $_primary_key variable specifies the primary key column name of the data table represented by the ORM model.

In addition, Kohana's ORM model provides many other variables and methods, such as $_belongs_to, $_has_many, $_has_one, find_all(), etc., we can use them when needed.

3. Using ORM methods

After we have defined the ORM model, we can use the methods provided by the ORM class to operate the database table.

The following are some commonly used ORM methods:

• create(): Create a new object and persist it to the database
• find(): Find a single object
• find_all(): Find multiple objects
• update(): Update objects in the database
• delete(): Delete objects from the database

The following is an example of using the ORM method:

<?php defined('SYSPATH') or die('No direct script access.');

class Controller_Articles extends Controller {

    public function action_index()
    {
        $articles = ORM::factory('Article')->find_all();

        foreach ($articles as $article) {
            echo $article->title . ' - ' . $article->body . '<br />';
        }
    }

}

In the above example, we use $articles = ORM::factory('Article')->find_all(); to find all articles and make the loop output the titles and texts of these articles.

4. Conclusion

In the Kohana framework, ORM provides a very convenient way to operate the database. Using ORM, we can quickly define the ORM model, and then use the methods provided by the ORM class to easily operate the database. Hope this article can help you better understand the use of ORM in Kohana framework.

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