<com:TContent ID="Main"> <h1>Creating Active Record Classes</h1> <p> We need to create two <a href="http://www.pradosoft.com/demos/quickstart/?page=Database.ActiveRecord">Active Record</a> classes, <tt>UserRecord</tt> and <tt>PostRecord</tt>, to represent data records in the <tt>users</tt> and <tt>posts</tt> tables, respectively. Active Record classes must extend from the base class <tt>ActiveRecord</tt>, and must define property names that matches with the field names of the corresponding table. </p> <p> To better organize our directories, we create a new directory <tt>protected/database</tt> to hold the class files. We also modify our application configuration by inserting the following lines. It is equivalent to adding the directory <tt>protected/database</tt> to PHP include_path, which allows us to use the classes without explicitly including them. </p> <com:TTextHighlighter CssClass="source" Language="xml"> <paths> <using namespace="Application.database.*" /> </paths> </com:TTextHighlighter> <p> Instead of writing the classes manually, we will use the <a href="?page=GettingStarted.Wsat">PRADO Web Site Administration Tool</a> to generate the classes for us. So we need to modify again our application configuration in the services section like follows: </p> <p class="block-content"> <com:TTextHighlighter CssClass="source" Language="xml"> <services> ... <service id="wsat" class="System.Wsat.TWsatService" Password="my_secret_password" /> </services> </com:TTextHighlighter> </p> <p class="block-content"> Then you are ready to go to: http://localhost/yoursite/index.php?wsat=TWsatLogin where you should see the following page: </p> <img src="<%~wsat_login.png%>" style="width: 700px;" /> <p class="block-content"> In the text field you need to type the password previosly specified in the service inclusion. This is part of a basic security system to avoid undesirable persons to use this tool. </p> <p class="block-content"> In order to generate AR classes you need to go to: http://localhost/divermania/index.php?wsat=TWsatGenerateAR by clicking the proper links in the welcome page. Then you should see the following page: </p> <img src="<%~blog_wsat_generate_ar.png%>" style="width: 700px;" /> <p> In the <tt>Output Folder</tt> field we used the <a href="http://www.pradosoft.com/demos/quickstart/?page=Fundamentals.Components">namespace format</a> again, the path <tt>Application.database</tt> indicates that we want to put our class's files in the <tt>protected/database/</tt> folder. The <tt>*</tt> in the <tt>Table Name</tt> field means that we want to generate all AR classes, you can specify a table name instead if you want to generate just a specific AR class. </p> <p> Afterward we should see the following directory structure with two new files under <tt>protected/database</tt>: </p> <img src="<%~ directories2.gif %>" class="output" /> <p> If we check the <tt>PostRecord</tt> class file, we should see something similar to the following content: </p> <com:TTextHighlighter CssClass="source" Language="php"> class PostRecord extends TActiveRecord { const TABLE='posts'; public $post_id; public $author_id; public $create_time; public $title; public $content; public $status; public static function finder($className=__CLASS__) { return parent::finder($className); } public static $RELATIONS = array ( 'author' => array(self::BELONGS_TO, 'UserRecord', 'author_id') ); public function __toString() { return $this->title; } } </com:TTextHighlighter> <p> As we see, for each field in the <tt>posts</tt> table, the class has a corresponding data member. The constant <tt>TABLE</tt> specifies the table name for the <tt>PostRecord</tt>. The static method <tt>finder()</tt> allows us to perform query and retrieve post data in terms of <tt>PostRecord</tt> objects. </p> <h1>Relationship Between Posts and Users</h1> <p> Recall that there was a foreign key relationship between the <tt>users</tt> and <tt>posts</tt> table. The entity-relationship diagram is shown below for convienence. </p> <img src="<%~ ER.gif %>" class="output" /> <p> From the entity-relationship diagram above, we see that the <tt>posts</tt> table contains a field named <tt>author_id</tt>. This <tt>author_id</tt> field is a foreign key to the reference table <tt>users</tt>. In particular, the values in the <tt>author_id</tt> field should be of that from the <tt>users</tt> table's <tt>username</tt> field. One of the consequence of this relationship, thinking in terms of objects, is that each "post" belongs to an "author" and one "author" may have many "posts". </p> <p> The static <tt>$RELATIONS</tt> property of <tt>PostRecord</tt> defines that the property <tt>$author</tt> belongs to an <tt>UserRecord</tt>. In <tt>array(self::BELONGS_TO, 'UserRecord')</tt>, the first element defines the relationship type, in this case <tt>self::BELONGS_TO</tt>. The second element is the name of related record, in this case an <tt>UserRecord</tt>. </p> <p> An array of <tt>UserRecord</tt> with and its corresponding posts may be fetched as follows. </p> <com:TTextHighlighter CssClass="source" Language="php"> $users = UserRecord::finder()->withPosts()->findAll(); </com:TTextHighlighter> <com:TipBox> The method <tt>withXXX()</tt> (where XXX is the relationship property name, in this case, <tt>Posts</tt>) fetches the corresponding <tt>PostRecords</tt> using a second query (not by using a join). The <tt>withXXX()</tt> method accepts the same arguments as other finder methods of TActiveRecord, e.g. <tt>withPosts('status = ?', 0)</tt>. </com:TipBox> <p> Further detailed documentation can be found in the quickstart <a href="http://www.pradosoft.com/demos/quickstart/?page=Database.ActiveRecord">Active Record</a> docs. </p> </com:TContent>