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The AbstractModel class's updated source code - PHP

In this ninth part of an 11-part series on method chaining, I will add three new chainable methods to the custom CodeIgniter model class we built in previous parts. You should find this a straightforward process, especially if you have a decent background in this framework’s database class.

TABLE OF CONTENTS:
  1. Method Chaining: Adding More Selecting Methods to the CodeIgniter Library
  2. Review: the AbstractModel class's source code
  3. Building the SELECT MIN, SELECT AVG and SELECT SUM parts of a SQL statement with chainable methods
  4. The AbstractModel class's updated source code
By: Alejandro Gervasio
Rating: starstarstarstarstar / 1
November 18, 2009

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As I sated in the section that you just read, below I listed the complete source code corresponding to the previous “AbstractModel” class, this time including the three chainable methods that were discussed earlier. Look at it, please:

The MIT License

 

Copyright (c) 2008 Simon Stenhouse

 

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

 

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

 

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 

 

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;

}

 

// Builds the select MIN part of the query

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

{

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

{

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

}

return $this;

}

 

// Builds the select AVG part of the query

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

{

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

{

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

}

return $this;

}

 

// Builds the select SUM part of the query

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

{

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

{

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

}

return $this;

}

}

Hopefully, with the complete source code of the above model class at your disposal, you’ll be able to grasp more quickly how each of its methods work, and how the method chaining approach has been used to implement them appropriately.

Finally, feel free introduce your own improvements to this custom CodeIgniter library to enhance its current functionality. The experience will be instructive and fun, trust me.

Final thoughts

That’s about it for the moment. In this ninth episode of the series, I added three new chainable methods to the custom CodeIgniter model class. This is certainly a process that should be pretty straightforward for you, especially if you have a decent background in this framework’s database class.

Moving forward, in the upcoming tutorial I’m going to keep adding more chainable methods to the class. These will be tasked with building the ORDER BY, LIKE, NOT LIKE and DISTINCT portions of a query.

Don’t miss the next part!



 
 
>>> More PHP Articles          >>> More By Alejandro Gervasio
 

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