Deleting database records with a final model class method - PHP

In the prior section, I showed you the partial definition of the model class, which is responsible for performing CRUD operations against a selected MySQL table. Nevertheless, the development of this class is still incomplete, since it’s necessary to add a method that deletes database rows; that is the “D” letter within the CRUD acronym.

Below I listed the full source code of the file that contains the model class, this time including the missing method. Take a look at this file:

(Model.php)

<?php

class Model

{

private $db = NULL;

private $table = 'users';

// constructor

public function __construct(MySQL $db, $table = '')

{

$this->db = $db;

if ($table !== '')

{

$this->table = $table;

}

}

// get all rows from the specified table

public function fetchAll()

{

$rows = array();

$this->db->query('SELECT * FROM ' . $this->table);

while ($row = $this->db->fetch())

{

$rows[] = $row;

}

return $rows;

}

// update/insert row

public function save(array $data, $id = NULL)

{

if (!empty($data))

{

foreach ($data as $field => $value)

{

$value = mysql_escape_string($value);

if (!is_numeric($value))

{

$data[$field] = ''' . $value . ''';

}

}

if ($id !== NULL)

{

$set = '';

foreach($data as $field => $value)

{

$set .= $field .'=' . $value . ',';

}

$set = substr($set, 0, -1);

$this->db->query('UPDATE ' . $this->table . ' SET ' . $set . ' WHERE id=' . (int)$id);

}

else

{

$fields = implode(',', array_keys($data));

$values = implode(',', array_values($data));

$this->db->query('INSERT INTO ' . $this->table . ' (' . $fields . ')' . ' VALUES (' . $values . ')');

}

}

}

// delete row

public function delete($id = NULL)

{

if ($id !== NULL)

{

$this->db->query('DELETE FROM ' . $this->table . ' WHERE id=' . (int)$id);

}

}

}// End Model class

Done. With the incorporation of the brand new “delete()” method, the model can perform true CRUD operations on a selected MySQL table. With this addition, the framework is also capable of handling the data layer through a compact API.

At this point, do you realize how the MVC structure which this framework relies on is starting to take shape? I bet you do. Even so, the best way to understand how to use the framework is by way of a concrete example that puts all of its building blocks to work together. This process will be tackled in the upcoming part.

Final thoughts

In this ninth episode of the series, I added to the framework an extensible model class, which as you saw, can be used for running CRUD operations against a selected MySQL database table.

In the next part, things will become even more interesting. I’m going to start developing a basic database-driven application by using the set of classes developed so far, which naturally will require coding a controller class as well.

Don’t miss the forthcoming tutorial!