Created
August 8, 2019 13:25
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a simple sample of PHP Method Chaining
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<?php | |
// taken from: https://stackoverflow.com/questions/3724112/php-method-chaining | |
class DBManager | |
{ | |
private $selectables = array(); | |
private $table; | |
private $whereClause; | |
private $limit; | |
public function select() { | |
$this->selectables = func_get_args(); | |
return $this; | |
} | |
public function from($table) { | |
$this->table = $table; | |
return $this; | |
} | |
public function where($where) { | |
$this->whereClause = $where; | |
return $this; | |
} | |
public function limit($limit) { | |
$this->limit = $limit; | |
return $this; | |
} | |
public function result() { | |
$query[] = "SELECT"; | |
// if the selectables array is empty, select all | |
if (empty($this->selectables)) { | |
$query[] = "*"; | |
} | |
// else select according to selectables | |
else { | |
$query[] = join(', ', $this->selectables); | |
} | |
$query[] = "FROM"; | |
$query[] = $this->table; | |
if (!empty($this->whereClause)) { | |
$query[] = "WHERE"; | |
$query[] = $this->whereClause; | |
} | |
if (!empty($this->limit)) { | |
$query[] = "LIMIT"; | |
$query[] = $this->limit; | |
} | |
return join(' ', $query); | |
} | |
} | |
// Now to use the class and see how METHOD CHAINING works | |
// let us instantiate the class DBManager | |
$testOne = new DBManager(); | |
$testOne->select()->from('users'); | |
echo $testOne->result(); | |
// OR | |
echo $testOne->select()->from('users')->result(); | |
// both displays: 'SELECT * FROM users' | |
$testTwo = new DBManager(); | |
$testTwo->select()->from('posts')->where('id > 200')->limit(10); | |
echo $testTwo->result(); | |
// this displays: 'SELECT * FROM posts WHERE id > 200 LIMIT 10' | |
$testThree = new DBManager(); | |
$testThree->select( | |
'firstname', | |
'email', | |
'country', | |
'city' | |
)->from('users')->where('id = 2399'); | |
echo $testThree->result(); | |
// this will display: | |
// 'SELECT firstname, email, country, city FROM users WHERE id = 2399' | |
?> |
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