PHP Implementation of MVC pattern example

{Some_text} {Some_more_text} Copy Code They don't make sense in the document, they mean just that PHP will replace it with something else. If you agree with this loosely described view, you will agree that the vast majority of template schemes do not effectively separate views and models. The template label will be replaced with what is stored in the model. Ask yourself a few questions when you implement the view: "Is it easy to replace the whole view?" "" How long does it take to implement a new view? "Can you easily replace the description language of the view?" (such as replacing an HTML document with a SOAP document in the same view) " Second, model The model represents the program logic. (often referred to as the business layer in an enterprise-level program) In general, the task of the model is to convert the original data into data that contains some meaning that will be displayed by the view. Typically, the model encapsulates the data query, possibly through some abstract data classes (the data access layer). For example, if you want to calculate the annual rainfall in the UK (just to find a better place for yourself), the model will receive a daily rainfall of ten years, calculate the average, and pass it on to the view. III. Controllers (Controller) Simply put, the controller is part of the first call to the HTTP request that is entered in the Web application. It checks the received requests, such as some get variables, to make the appropriate feedback. Before you write out your first controller, it's hard to start writing other PHP code. The most common usage is the structure of a switch statement in index.php: Switch ($_get[' ViewPage ')} { Case "News": $page =new Newsrenderer; Break Case "Links": $page =new Linksrenderer; Break Default $page =new Homepagerenderer; Break } $page->display (); ?> Copy Code This code mixes process-and object-oriented code, but this is usually the best choice for small sites. Although the above code can also be optimized. A controller is actually a control that is used to trigger a binding between a model's data and a view element. Here is a simple example of using the MVC pattern. First we need a database access class, which is a generic class. /** * A Simple class for querying MySQL */ Class DataAccess { /** * Private * $DB stores a database resource */ var $db; /** * Private * $query stores a query resource */ var $query; Query Resource //! A constructor. /** * Constucts a new DataAccess object * @param $host string hostname for DBServer * @param $user string DBServer user * @param $pass string dbserver user password * @param $db String database name */ function DataAccess ($host, $user, $pass, $db) { $this->db=mysql_pconnect ($host, $user, $pass); mysql_select_db ($db, $this->db); } //! An accessor /** * Fetches a query resources and stores it in a local member * @param $sql string The database query to run * @return void */ function Fetch ($sql) { $this->query=mysql_unbuffered_query ($sql, $this->db); Perform query here } //! An accessor /** * Returns an associative array of a query row * @return Mixed */ function GetRow () { if ($row =mysql_fetch_array ($this->query,mysql_assoc)) return $row; Else return false; } } ?> Copy Code Put the model on top of it. /** * fetches ' products ' from the database * link:http://bbs.it-home.org */ Class ProductModel { /** * Private * $dao An instance of the DataAccess class */ var $dao; //! A constructor. /** * Constucts a new ProductModel object * @param $dbobject An instance of the DataAccess class */ Function ProductModel (& $dao) { $this->dao=& $dao; } //! A Manipulator /** * tells the $dboject to store this query as a resource * @param $start the row to start from * @param $rows The number of rows to fetch * @return void */ function listproducts ($start =1, $rows =50) { $this->dao->fetch ("SELECT * FROM Products LIMIT". $start. ",". $rows); } //! A Manipulator /** * tells the $dboject to store this query as a resource * @param $id A primary key for a row * @return void */ function Listproduct ($id) { $this->dao->fetch ("SELECT * FROM Products WHERE productid= '". $id. ""); } //! A Manipulator /** * Fetches a product as an associative array from the $dbobject * @return Mixed */ function GetProduct () { if ($product = $this->dao->getrow ()) return $product; Else return false; } } ?> Copy Code Note: Between the model and the data access class, they never have more than one line of interaction--no more than one line is passed, which slows the program down very quickly. The same program for a class that uses patterns, it just needs to keep one row in memory (row)--the other to the saved query resource--in other words, we let MySQL keep the results for us. Next is the view (the following code removes the HTML content). /** * Binds product data to HTML rendering * link:http://bbs.it-home.org */ Class ProductView { /** * Private * $model An instance of the ProductModel class */ var $model; /** * Private * $output rendered HTML is stored here for display */ var $output; //! A constructor. /** * Constucts a new ProductView object * @param $model An instance of the ProductModel class */ Function ProductView (& $model) { $this->model=& $model; } //! A Manipulator /** * Builds the top of an HTML page * @return void */ function header () { } //! A Manipulator /** * Builds the bottom of an HTML page * @return void */ function Footer () { } //! A Manipulator /** * Displays a single product * @return void */ function Productitem ($id =1) { $this->model->listproduct ($id); while ($product = $this->model->getproduct ()) { Bind data to HTML } } //! A Manipulator /** * Builds a product table * @return void */ function producttable ($rownum =1) { $rowsperpage = ' 20 '; $this->model->listproducts ($rownum, $rowsperpage); while ($product = $this->model->getproduct ()) { Bind data to HTML } } //! An accessor /** * Returns the rendered HTML * @return String */ function display () { return $this->output; } } ?> Copy Code Finally, the controller, we will implement the view as a subclass. /** * Controls the application */ Class Productcontroller extends ProductView { //! A constructor. /** * Constucts a new Productcontroller object * @param $model An instance of the ProductModel class * @param $getvars The incoming HTTP GET method variables */ Function Productcontroller (& $model, $getvars =null) { ProductView::P Roductview ($model); $this->header (); Switch ($getvars [' view ']) { Case "Product": $this->productitem ($getvars [' id ']); Break Default if (Empty ($getvars [' rownum '])) { $this->producttable (); } else { $this->producttable ($getvars [' rownum ']); } Break } $this->footer (); } } ?> Copy Code Note: This is not the only way to implement MVC-for example, you can integrate the view with the controller implementation model. This is just one way to demonstrate the pattern. The index.php file looks like this: Require_once (' lib/dataaccess.php '); Require_once (' lib/productmodel.php '); Require_once (' lib/productview.php '); Require_once (' lib/productcontroller.php '); $dao =& new DataAccess (' localhost ', ' user ', ' Pass ', ' dbname '); $productModel =& New ProductModel ($dao); $productController =& New Productcontroller ($productModel, $_get); echo $productController->display (); ?> Copy Code There are some techniques for using the controller, which you can do in PHP: $this->{$_get[' method '} ($_get[' param ')); It is recommended that you define the namespace form (namespace) of the program URL so that it compares specifications such as: "Index.php?class=productview&method=productitem&id=4" Copy Code Through it you can handle the controller: $view =new $_get[' class '); $view->{$_get[' method '] ($_get[' id '); Copy Code Sometimes it's not easy to build a controller, such as when it comes to balancing development speed and adaptability. A good place to get inspired is the Java Struts of the Apache group, whose controllers are completely defined by the XML document.

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