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Adding more chainable methods to the abstract model class - PHP

In this eleventh part of a 12-part series on method chaining, I will finish building the custom CodeIgniter library we've been working on by adding to it some very useful features. When we're done, the library will be able to autoload a specified model and validate input data.

TABLE OF CONTENTS:
  1. Completing a CodeIgniter Library with Method Chaining
  2. Adding more chainable methods to the abstract model class
  3. Autoloading models and validating incoming data
  4. The final version of the abstract model class
By: Alejandro Gervasio
Rating: starstarstarstarstar / 1
December 02, 2009

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Definitely, it’d be useful to list the full source code of the abstract model class as it was in the preceding tutorial before I start adding some other methods to it.

Given that, here’s the complete signature of the class, as a quick reminder:

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;

}

 

// 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;

}

}

If you pay attention to the above “AbstractModel” class and closely analyze the implementation of its methods, you’ll realize that despite its rather lengthy source code, its structure is actually very modular and easy to follow.

This permits you to quickly grasp how it works, so I’m going to code the methods that are charged first with building the HAVING, NOT HAVING and LIMIT sections of a query, and second with counting the rows of the database table associated with the model.

In summary, the respective definitions of these methods are as following:

// 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);

} 

As you can see above, the first three methods are chainable also, and are simple wrappers for their counterparts defined within the native CodeIgniter database class. If you’re familiar with the class, then you shouldn’t have major problems understanding how they work.

Finally, the remaining ones aren’t chainable but perform two crucial tasks: counting the number of rows retrieved by a dynamically-generated retrieving operation, and determining the total number of rows contained in the database table associated with the model.

Well, at this point the abstract model class has become even more functional, due to the addition of the group of methods that you saw before. So, I’m going to define a couple more methods, which will accomplish two truly relevant operations: recursively autoading a specified model, and validating the data used when inserting and updating a particular database row.

These two core methods will be defined and discussed in detail in the section to come. Therefore, to learn more about them, click on the link below and keep reading.



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

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