The final version of the abstract model class - PHP

As I said in the previous section, here’s the complete source code that corresponds to the abstract model class, so you can see more clearly how it looks when finished:

<?php

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.

// register file extensions and the method that will be used for autoloading models

spl_autoload_register(NULL, FALSE);

spl_autoload_extensions('.php');

spl_autoload_register(array('AbstractModel','autoload'));

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;

}

// Builds the JOIN part of the query

public function join($table, $join, $join_type = '')

{

if ( !empty($table) AND !empty($join))

{

$this->db->join($table, $join, $join_type);

}

return $this;

}

// Builds the ORDER BY part of the query

public function order_by($field = 'id', $order = 'ASC')

{

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

{

$this->db->order_by($field, $order);

}

return $this;

}

// Builds the GROUP BY part of the query

public function group_by($field)

{

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

{

$this->db->group_by($field);

}

return $this;

}

// Builds the LIKE part of the query using the AND operator

public function like($field, $match, $position = '')

{

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

{

$this->db->like($field, $match, $position);

}

return $this;

}

// Builds the OR LIKE part if the query using the OR operator

public function or_like($field, $match, $position = '')

{

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

{

$this->db->or_like($field, $match, $position);

}

return $this;

}

// Builds the NOT LIKE part of the query

public function not_like($field, $match, $position = '')

{

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

{

$this->db->not_like($field, $match, $position);

}

return $this;

}

// Builds the DISTINCT part of the query

public function distinct()

{

$this->db->distinct();

return $this;

}

// Builds the WHERE part of the query using AND and other operators

public function get_where($where, $protect_identifiers = TRUE)

{

if ((is_string($where) OR is_array($where)) AND !empty($where))

{

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

}

return $this;

}

// Builds the OR WHERE part of the query using OR and other operators

public function get_or_where($where, $protect_identifiers = TRUE)

{

if ((is_string($where) OR is_array($where)) AND !empty($where))

{

$this->db->or_where($where, $protect_identifiers);

}

return $this;

}

// Builds the WHERE IN part of the query

public function where_in($field, $values)

{

if (in_array($field, $this->fields, TRUE) AND is_array($values) AND !empty($values))

{

$this->db->where_in($field, $values);

}

return $this;

}

// Builds the WHERE NOT IN part of the query

public function where_not_in($field, $values)

{

if (in_array($field, $this->fields, TRUE) AND is_array($values) AND !empty($values))

{

$this->db->where_not_in($field, $values);

}

return $this;

}

// Builds the OR WHERE NOT IN part of the query using the OR operator

public function or_where_not_in($field, $values)

{

if (in_array($field, $this->fields, TRUE) AND is_array($values) AND !empty($values))

{

$this->db->or_where_not_in($field, $values);

}

return $this;

}

// Builds the HAVING part of the query

public function having($field, $value = '', $protect_identifiers = TRUE)

{

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

{

$this->db->having($field, $value, $protect_identifiers);

}

return $this;

}

// Builds the OR HAVING part of the query using the OR operator

public function or_having($field, $value = '', $protect_identifiers = TRUE)

{

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

{

$this->db->or_having($field, $value, $protect_identifiers);

}

return $this;

}

// Builds the LIMIT part of the query

public function limit($limit = 0)

{

if ($limit != 0)

{

$limit = (int)abs($limit);

$this->db->limit($limit);

}

return $this;

}

// Determines the number of rows produced by an Active Record query

public function count_all_results($table = '')

{

return $this->db->count_all_results($table);

}

// Determines the number of rows contained in a given table

public function count_all($table)

{

$table = $this->db->table_exists($table) ? $table : $this->table;

return $this->db->count_all($table);

}

// Autoloads recursively child models required by the Abstract Model class

public static function autoload($model)

{

// Don't attempt to autoload CI_ or MY_ prefixed classes

if (in_array(substr($model, 0, 3), array('CI_', 'MY_')))

{

return;

}

// Set path and model

$path = APPPATH . '/models/';

$model = strtolower($model) . EXT;

// try to include recursively the model file

$rit = new RecursiveIteratorIterator(new RecursiveDirectoryIterator($path));

foreach ($rit as $entry)

{

if ($model === $entry->getFileName())

{

require_once($entry->getPathname());

return;

}

}

show_error('Model class not found.');

}

// Validates model data

protected function validate($data)

{

// If no validation rules were set trigger an error

if (empty($this->validation))

{

$this->error = 'No validation rules were set for the model.';

return FALSE;

}

// Load CI validation library

$this->ci->load->library('validation');

// Load CI language file for validation

$this->ci->lang->load('validation');

// reset error messages

$this->error = array();

foreach ($this->validation as $field => $rules)

{

$exprules = explode('|', $rules);

// if the field is not required check next one

if (! in_array('required', $exprules, TRUE))

{

continue;

}

// Iterates through the validation rules

foreach ($exprules as $rule)

{

// Removes the parameter from the rule (when specified)

$param = FALSE;

if (preg_match("/(.*?)\[(.*?)\]/", $rule, $match))

{

$rule = $match[1];

$param = $match[2];

}

// Calls the validation method that corresponds to the rule

if (method_exists($this->ci->validation, $rule))

{

$result = $this->ci->validation->$rule($data[$field], $param);

}

elseif (function_exists($rule))

{

// Tries to run a native PHP function if method of CI validation class doesn't exist

$result = $rule($data[$field]);

}

// if an offending field was found store error message in error array

if ($result === FALSE)

{

$this->error[] = sprintf($this->ci->lang->line($rule), $field);

}

}

}

return empty($this->error) ? TRUE : FALSE;

}

// Returns error string when performing validation

protected function get_error_string()

{

$str = '';

$error_sufix = str_replace('<', '</', $this->error_prefix);

foreach ($this->error as $error)

{

$str .= $this->error_prefix . $error . $error_sufix;

 }

return $str;

}

}

That took a pretty long time to read, right? Don’t get tired now; you’ve learned how to apply the method chaining approach to building a PHP application that can be used in a real-world environment. Finally, before you move on and read the conclusion, feel free to introduce your own enhancements to the previous “AbstractModel” class, in case you want to use it when developing database-driven programs with CodeIgniter.

Final thoughts

That’s all for now. In this penultimate episode of the series, I finished building this custom library for CodeIgniter by adding to it some really useful features, such as the ability to autoload a specified model and validate input data as well.

However, if you’re anything like me, then a this point you may want to see how this library can be used for developing a database-driven application with CodeIgniter. In the last part of the series, I’m going to build a sample program that will reveal not only the real functionality of the library, but the convenience of using its chainable methods.

Don’t miss the next part!