Help creating my first class

[Kyle W]

I figure if I can get walked through this class I should be well on my way to creating my own.

What I want to accomplish is a class to create a form, something very close to one I found on Google (http://php.xivix.net/php_7_Object_Oriented_Forms), only not as advanced. I just want the class to create a template for the form and a variable inside to display all text fields that are created (just setting it up for text fields will be fine).

So the class would print from <form action="$var"> down to </form> including the submit button. The only problem is I can only figure out how to add a single text field. How do I add any number of fields?

[bhanson]

It might be helpful if you posted what you have so far.

Basically though, you will store your "fields" in an array, and then you can call a method to add another field to the array.

<?php

class Form
{
    private $_fields = array();

    public function addField($string)
    {
        $this->_fields[] = $string;
        return $this;
    }

    public function getFields()
    {
        return $this->_fields;
    }
}

$form = new Form();
$form->addField('Foo')
     ->addField('Bar')
     ->addField('Baz');


print_r($form->getFields());

Output

Array
(
    [0] => Foo
    [1] => Bar
    [2] => Baz
)

Edit:

Here is a slightly more complex example using object composition.

<?php

$form = new Form();
$form->setAction('page2.php')
     ->addElement(new Form_Element_Text('foo'))
     ->addElement(new Form_Element_Text('bar'))
     ->addElement(new Form_Element_Submit('submit'));

echo $form->render();

class Form
{
    protected $_elements = array();
    protected $_action   = null;
    protected $_method   = 'post';

    public function addElement(Form_Element $element)
    {
        $this->_elements[] = $element;
        return $this;
    }

    public function setAction($action)
    {
        $this->_action = $action;
        return $this;
    }

    public function setMethod($method)
    {
        $this->_method = $method;
        return $this;
    }

    public function render()
    {
        $output = '<form action="' . $this->_action . '" method="' . $this->_method . '">';
        foreach ($this->_elements as $element)
        {
            $output .= $element->getHtml();
        }
        $output .= '</form>';
        return $output;
    }
}

abstract class Form_Element
{
    protected $_name;

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

    abstract public function getHtml();
}

class Form_Element_Text extends Form_Element
{
    public function getHtml()
    {
        return '<input type="text" name="' . $this->_name . '" />';
    }
}

class Form_Element_Submit extends Form_Element
{
    public function getHtml()
    {
        return '<input type="submit" name="' . $this->_name . '" />';
    }
}

Output:

<form action="page2.php" method="post"><input type="text" name="foo" /><input type="text" name="bar" /><input type="submit" name="submit" /></form>

It's very basic, but should help demonstrate how objects can work together.

[bhanson]

I had a spare hour so I extended it to include Validation support.

Obviously it's still rough, but it should be functional and easily extendable.

Library: (each of these classes should really be in a separate file)

class Form
{
    protected $_elements = array();
    protected $_action   = null;
    protected $_method   = 'post';

    public function __construct()
    {
        $this->init();
    }

    public function init()
    {}

    public function addElement(Form_Element $element)
    {
        if (null === $element->getName()) {
            throw new Exception('Element must have name');
        }

        $this->_elements[$element->getName()] = $element;

        return $this;
    }

    public function setAction($action)
    {
        $this->_action = $action;
        return $this;
    }

    public function setMethod($method)
    {
        $this->_method = $method;
        return $this;
    }

    public function render()
    {
        $output = '<form action="' . $this->_action . '" method="' . $this->_method . '">';
        foreach ($this->_elements as $element) {
            $output .= '<pre>' . print_r($element->getErrors(), true) . '</pre>';
            $output .= '<p>' . $element->getHtml() . '</p>';
        }
        $output .= '</form>';
        return $output;
    }

    public function isValid(array $data)
    {
        $valid = true;
        foreach ($this->getElements() as $key => $element) {
            if (isset($data[$key])) {
                $valid = $element->isValid($data[$key]) && $valid;
                $element->setValue($data[$key]);
            } else {
                $valid = $element->isValid(null) && $valid;
            }
        }
        return $valid;
    }

    public function getElements()
    {
        return $this->_elements;
    }
}

abstract class Form_Element
{
    protected $_name = null;
    protected $_validators = array();
    protected $_value = null;
    protected $_errors = array();

    public function __construct($name = null)
    {
        $this->setName($name);
    }

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

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

    public function setValue($string)
    {
        $this->_value = $string;
    }

    public function addValidator(Validate $validator)
    {
        $this->_validators[] = $validator;
    }

    public function isValid($string)
    {
        $valid = true;
        foreach ($this->getValidators() as $validator) {
            if ($validator->isValid($string)) {
                $valid = true && $valid;
            } else {
                $valid = false;
                $this->_errors[] = $validator->getError();
            }
        }
        return $valid;
    }

    public function getErrors()
    {
        return $this->_errors;
    }

    public function getValidators()
    {
        return $this->_validators;
    }

    abstract public function getHtml();
}

class Form_Element_Text extends Form_Element
{
    public function getHtml()
    {
        return '<input type="text" name="' . $this->_name . '" value="' . $this->_value . '"/>';
    }
}

class Form_Element_Submit extends Form_Element
{
    public function getHtml()
    {
        return '<input type="submit" name="' . $this->_name . '" />';
    }
}

abstract class Validate
{
    protected $_options = array();
    protected $_error = null;

    public function __construct(array $options = array())
    {
        $this->setOptions($options);
    }

    public function setOptions(array $options = array())
    {
        $this->_options = $options;
    }

    public function getOption($key)
    {
        return $this->_options[$key];
    }

    protected function _setError($text)
    {
        $this->_error = $text;
    }

    public function getError()
    {
        if (null === $this->_error) {
            return false;
        } else {
            return $this->_error;
        }
    }

    abstract public function isValid($string); 
}

class Validate_StringLength extends Validate
{
    public function isValid($string)
    {
        $length = strlen($string);
        if (($length >= $this->getOption('min')) && ($length <= $this->getOption('max'))) {
            return true;
        }
        $this->_setError("\"$string\" length is not >= {$this->getOption('min')} && <= {$this->getOption('max')}");
        return false;
    }
}

class Validate_Numeric extends Validate
{
    public function isValid($string)
    {
        if (is_numeric($string)) {
            return true;
        }
        $this->_setError("$string is not numeric");
        return false;
    }
} 

Build your form:

class ExampleForm extends Form
{
    public function init()
    {
        $this->setMethod('post');

        $name = new Form_Element_Text('name');
        $name->addValidator(
            new Validate_StringLength(array(
                'min' => 4,
                'max' => 20,
            ))
        );

        $age = new Form_Element_Text('age');
        $age->addValidator(new Validate_Numeric());
        $age->addValidator(
            new Validate_StringLength(array(
                'min' => 1,
                'max' => 2,
            ))
        );

        $submit = new Form_Element_Submit('submit');

        $this->addElement($name)
             ->addElement($age)
             ->addElement($submit);
    }
} 

Use it!

$form = new ExampleForm();
$form->setAction($_SERVER['PHP_SELF']);

if (!empty($_POST)) {
    if ($form->isValid($_POST)) {
        echo "Valid form!\n";
    }
}

echo $form->render(); 

This displays the form, validates it, displays error messages, and auto repopulates data automatically for you.

If anyone has questions feel free to ask.

[AnthonySterling]

Brad,

First off, great example! It's really good to see people post advanced examples for others...

Secondly, could you please tell me why you coded Form_Element::isValid() the way you have, more specifically "$valid = true && $valid;" and not like the following...

<?php
public function isValid($string)
{
    $valid = true;
    foreach ($this->getValidators() as $validator) {
        if (!$validator->isValid($string)) {
            $valid = false;
            $this->_errors[] = $validator->getError();
        }
    }
    return $valid;
}
?>

Am I missing something?

[bhanson]

Brad,

First off, great example! It's really good to see people post advanced examples for others...

Secondly, could you please tell me why you coded Form_Element::isValid() the way you have, more specifically "$valid = true && $valid;" and not like the following...

<?php
public function isValid($string)
{
    $valid = true;
    foreach ($this->getValidators() as $validator) {
        if (!$validator->isValid($string)) {
            $valid = false;
            $this->_errors[] = $validator->getError();
        }
    }
    return $valid;
}
?>

Am I missing something?

I think I had some extra code there which needed a true case, but I guess I removed it and never refactored.

There's some other things that should probably be changed as well, but I'll leave that as an exercise for anyone who may want to use the code. I don't actually build libraries anymore for common functionality in my projects, I reuse existing ones. Overall it saves me a lot of time.

[AnthonySterling]

Thanks for the reply Brad, I figured as much.

I just wanted to be sure I wasn't missing something, I hope you have a great new year and hope to see more of your code in 2009.

Anthony.

[Kyle W]

Hey thanks for all the input! And the same as SBUK said, have a great new year and hope to see you all in '09! Have a safe holiday!

[binarysys]

I had a spare hour so I extended it to include Validation support.

Obviously it's still rough, but it should be functional and easily extendable.

Library: (each of these classes should really be in a separate file)

[PHP]class Form
{
protected $_elements = array();
protected $_action = null;
protected $_method = 'post';

public function __construct()
{
$this->init();
}

public function init()
{}

// ...

Truly a great example! Wish I had seen this when I was trying to figure out OOP