The AbstractModel class's full source code - PHP

Certainly, the best way to understand how the “AbstractModel” class does its business is by showing its entire source code, including the pair of chainable methods that were defined in the previous section.

With that idea in mind, below I’ve included the class, so you can see at a glance how it looks. Here it is:

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Copyright (c) 2008 Simon Stenhouse

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class AbstractModel

{

protected $table = '';

protected $fields = array();

protected $validation = array();

protected $error_prefix = '<p>';

protected static $instance = NULL;

protected $ci = NULL;

protected $db = NULL;

// Factory method that creates a singleton model object

public static function factory($model)

{

if (self::$instance == NULL)

{

$model = ucfirst($model);

self::$instance = new $model;

}

return self::$instance;

}

// Constructor

public function __construct()

{

$this->ci = & get_instance();

$this->db = $this->ci->db;

$table = strtolower(get_class($this)) . 's';

if ($this->db->table_exists($table))

{

$this->table = $table;

$this->fields = $this->db->field_names($this->table);

}

else

{

return;

}

}

// Sets a new property for the model

function __set($property, $value)

{

if(in_array($property, array_merge($this->fields, array('error', 'result')), TRUE))

{

$this->$property = $value;

}

}

// Gets the value of an existing property of the model

function __get($property)

{

if(isset($this->$property))

{

return $this->$property;

}

return NULL;

}

// Fetches rows from specified table

public function fetch($limit = NULL, $offset = NULL)

{

$data = array();

foreach ($this->fields as $field)

{

if (isset($this->$field) AND $this->$field != '')

{

$data[$field] = $this->$field;

}

}

$query = !empty($data) ? $this->db->get_where($this->table, $data, $limit, $offset) : $this->db->get($this->table, $limit, $offset);

if ($query->num_rows() > 0)

{

$this->result = $query->result();

return $this;

}

$this->error = 'No rows were returned.';

return FALSE;

}

// Inserts a new row into the specified database table

public function save()

{

$data = array();

foreach ($this->fields as $field)

{

if (isset($this->$field))

{

$data[$field] = $this->$field;

}

}

// if there is any data available go ahead and save/update row

if( !empty($data))

{

// validate input data

if ($this->validate($data) === FALSE)

{

$this->error = $this->get_error_string();

return FALSE;

}

// if id property has been set in the controller update existing row

if ( !empty($this->id))

{

// Update existing record

$this->db->where('id', $this->id);

$this->db->update($this->table, $data);

}

else

{

// otherwise insert new row

$this->db->insert($this->table, $data);

$this->id = $this->db->insert_id();

}

return TRUE;

}

$this->error = 'No valid data was provided to save row.';

return FALSE;

}

// Deletes a row

public function delete()

{

if (isset($this->id))

{

$this->db->where('id', $this->id);

$this->db->delete($this->table);

return TRUE;

}

$this->error = 'Error deleting row.';

return FALSE;

}

// Builds SELECT part of the query

public function select($select = '*', $protect_identifiers = TRUE)

{

if ($select != '*' AND !empty($select))

{

$select = explode(',', $select);

foreach ($select as $key => $field)

{

if ( !in_array($field, $this->fields, TRUE))

{

unset($select[$key]);

}

}

$select = !empty($select) ? $select : '*';

}

$this->db->select($select, $protect_identifiers);

return $this;

}

// Builds the select MAX part of the query

public function select_max($field, $alias = '')

{

if (in_array($field, $this->fields, TRUE))

{

$this->db->select_max($field, $alias);

}

return $this;

}

}

There you have it. At this stage, the above “AbstractModel” class looks much more functional due to the incorporation of the “select()” and “select_max()” methods, which can be easily chained to others as well. As usual, feel free to edit the class's source code and introduce your own enhancements. That will be a good exercise for improving your understanding of method chaining in PHP 5.

Final thoughts

That’s it for now. Over this eighth chapter of the series, I defined and implemented a few more methods for the custom CodeIgniter model class. As you saw for yourself, some of these methods are chainable, which hopefully demonstrates the actual benefits of using this programming methodology.

In the next episode, things will become even more interesting. I’m going to define more chainable methods within the model class, which will allow you to create the SELECT MIN, SELECT AVG and SELECT SUM parts of a SQL query.

Therefore, here’s my final suggestion: don’t miss the upcoming part!