Fluent interface and method chaining in PHP and JavaScript

Mofiqul Islam — Wed, 15 Aug 2018 05:52:23 +0000

A Fluent Interface is an object oriented API that provides "more readable" code.
A fluent interface allows you to chain method calls, which results in less typed characters when applying multiple operations on the same object.

read more about fluent interface

Fluent interface let us write code like this:

$programmer->born()->eat()->sleep()->code()->die();

instead of

$programmer->born();
$programmer->eat();
$programmer->sleep();
$programmer->code();
$programmer->die();

Implementation:
A fluent interface is normally implemented by using method chaining to implement method cascading (in languages that do not natively support cascading), concretely by having each method return this (self). Stated more abstractly, a fluent interface relays the instruction context of a subsequent call in method chaining, where generally the context is

defined through the return value of a called method
self-referential, where the new context is equivalent to the last context
terminated through the return of a void context.

from here

A simple PHP example

class Person{
  private $_name;
  private $_sex;
  private $_age;
  private $_height;
  private $_weight;

  public function name($name){
    $this->_name = $name;
    return $this;
  }

  public function sex($sex){
    $this->_sex = $sex;
    return $this;
  }

  public function age($age){
    $this->_age = $age;
    return $this;
  }

  public function height($h){
    $this->_height = $h;
    return $this;
  }

  public function weight($w){
    $this->_weight = $w;
    return $this;
  }
  public function save(){
    $properties = get_object_vars($this);
    $str = '';
    foreach($properties as $property){
        $str .= $property.' ';
    }
    return $str;
  }
}

Now we can call the methods on the object of Person like

$p = new Person();
$res = $p->name('Sonia')->sex('Female')->age('30')->height('5.8')->weight('51')->save();
echo $res; # Sonia Female 30 5.8 51

we can call only few of them

$res = $p->name('Sonia')->sex('Female')->age('30')->save();
echo $res; # Sonia Female 30

we also can call chain methods in deffrent order

$res = $p->name('Sonia')->height('5.8')->weight('51')->sex('Female')->age('30')->save();
echo $res; # Sonia Female 30 5.8 51

Same in JavaScript

var Person = function() {
  this._name = '';
  this._sex = '';
  this._age = '';
  this._height = '';
  this._weight = '';
};

Person.prototype.name = function(name) {
  this._name = name;
  return this;
};

Person.prototype.sex = function(sex) {
  this._sex = sex;
  return this;
};

Person.prototype.age = function(age) {
  this._age = age;
  return this;
};

Person.prototype.height = function(height) {
  this._height = height;
  return this;
};

Person.prototype.weight = function(weight) {
  this._weight = weight;
  return this;
};


Person.prototype.save = function() { 
  let str = '';
  for(let property of Object.keys(this)){
    str += this[property] + ' ';
  } 
  console.log(str);
};

Using it

new Person().name('Sonia').sex('Female').age('30').height('5.8').weight('51').save();
// Sonia Female 30 5.8 51

How do you write your PHP validator?

Mofiqul Islam — Sun, 12 Aug 2018 15:53:47 +0000

I recently started to write an MVC framework in PHP for the better understanding of object-oriented design and how the framework works. Today I was writing a validator for the MVC. I was wondering if there is are better ways to do than what I did.

Here is my validator class

class Validator{

    private $_errors = [];


    public function validate($src, $rules = [] ){

        foreach($src as $item => $item_value){
            if(key_exists($item, $rules)){
                foreach($rules[$item] as $rule => $rule_value){

                    if(is_int($rule))
                         $rule = $rule_value;

                    switch ($rule){
                        case 'required':
                        if(empty($item_value) && $rule_value){
                            $this->addError($item,ucwords($item). ' required');
                        }
                        break;

                        case 'minLen':
                        if(strlen($item_value) < $rule_value){
                            $this->addError($item, ucwords($item). ' should be minimum '.$rule_value. ' characters');
                        }       
                        break;

                        case 'maxLen':
                        if(strlen($item_value) > $rule_value){
                            $this->addError($item, ucwords($item). ' should be maximum '.$rule_value. ' characters');
                        }
                        break;

                        case 'numeric':
                        if(!ctype_digit($item_value) && $rule_value){
                            $this->addError($item, ucwords($item). ' should be numeric');
                        }
                        break;
                        case 'alpha':
                        if(!ctype_alpha($item_value) && $rule_value){
                            $this->addError($item, ucwords($item). ' should be alphabetic characters');
                        }
                    }
                }
            }
        }    
    }

    private function addError($item, $error){
        $this->_errors[$item][] = $error;
    }


    public function error(){
        if(empty($this->_errors)) return false;
        return $this->_errors;
    }
}

Now testing the validator.

$data = ['username' => '', 'password' => 'pass'];
$rules = [
    'username' => ['required', 'minLen' => 6,'maxLen' => 150, 'alpha'],
    'password' => ['required', 'minLen' => 8]
];
$v = new Validator();
$v->validate($data, $rules);
if($v->error()){
    print_r($v->error());
} else{
    echo 'Ok';
}

Result

Array
(
    [username] => Array
        (
            [0] => Username required
            [1] => Username should be minimum 6 characters
            [2] => Username should be alphabetic characters
        )

    [password] => Array
        (
            [0] => Password should be minimum 8 characters
        )

)

DEV Community: Mofiqul Islam

Fluent interface and method chaining in PHP and JavaScript

How do you write your PHP validator?