Crude Form class example

CrudeForm.php

<?php

/**
 * A very basic crude Form class.
 * It can have input controls + will know their values.
 * Also will know if it (the form) was itself submitted.
 */
class CrudeForm {

	/** @var string Form name for identifying the form. **/
	protected $name;

	/** @var array Container for form controls' HTML. **/
	protected $controls = array();

	/** @var bool Was this form rendered? **/
	protected $rendered = false;

	/**
	 * Create new form. It is _your_ responsibility not to create two forms
	 * with the same name
	 */
	public function __construct(string $name) {
		$this->name = sprintf("_crudeform_%s", $name);
	}

	/**
	 * Get form name
	 */
	public function getName() {
		return $this->name;
	}

	/**
	 * Add textbox to the form.
	 * Shorthand for self::addInput().
	 */
	public function addTextbox(string $name, string $label) {

		$this->addInput($name, $label, 'text');
		return $this;

	}

	/**
	 * Add submit button to the form.
	 * Shorthand for self::addInput().
	 */
	public function addSubmit(string $name) {

		$this->addInput($name, null, 'submit');
		return $this;

	}

	/**
	 * Add an imput to the form.
	 */
	public function addInput(string $name, $label, string $type) {

		$uniqueName = $this->buildInputName($name);
		$this->controls[$name] = sprintf(
			"<label for='%s'>%s</label><input type='%s' name='%s'>",
			$uniqueName,
			$label,
			$type,
			$uniqueName
		);

		return $this;

	}

	/**
	 * Render the form. Output its final HTML to the page.
	 */
	public function render() {

		if ($this->rendered) {
			throw new \LogicException(sprintf("From '%s' has already been rendered.", $this->name));
		}

		$html = sprintf(
			"<form name='%s' method='post'>%s%s</form>",
			$this->name,
			self::getFormHiddenIdInput(),
			implode('<br>', $this->controls)
		);
		echo $html;

		$this->rendered = true;

	}

	/**
	 * Was this form submitted during the last request?
	 */
	public function wasSubmitted() {
		return isset($_POST[$this->getHiddenIdName()]);
	}

	/**
	 * Return an array containing values of form's controls.
	 */
	public function getValues() {

		$values = array();

		// Go through each of this form's controls and check if they have
		// any values in the POST data.
		foreach ($this->controls as $name => $controlHtml) {

			// This control's value will be recognized by its unique name
			// in the POST data array.
			$uniqueName = $this->buildInputName($name);

			if (isset($_POST[$uniqueName])) {
				$values[$name] = $_POST[$uniqueName];
			}

		}

		return $values;

	}

	// Helpers

	/**
	 * Build a page-wide unique name for _this_ input and _this_ form.
	 */
	protected function buildInputName(string $rawName) {

		return sprintf('_crudeform_input_%s', self::hashVariable([
			$this->name,
			$rawName
		]));

	}

	/**
	 * Returns the name of the form's hidden identification input.
	 */
	protected function getHiddenIdName() {
		return sprintf('_crudeform_id_%s', md5($this->name));
	}

	/**
	 * Returns HTML of the form's hidden ID input.
	 */
	protected function getFormHiddenIdInput() {

		return sprintf(
			"<input type='hidden' name='%s'>", $this->getHiddenIdName()
		);

	}

	/**
	 * Hash whatever is given to this.
	 */
	protected static function hashVariable() {
		return md5(json_encode(func_get_args()));
	}

}

index.php

<?php

include __DIR__ . "/CrudeForm.php";

// Build all forms

$formOne = new CrudeForm('first_form');
$formOne->addTextbox('first_textbox', 'Your name:');
$formOne->addInput('first_checkbox', 'Are you cool?', 'checkbox');
$formOne->addSubmit('first_submit', 'Test me');

$formTwo = new CrudeForm('second_form');
$formTwo->addTextbox('second_textbox', 'Your second name:');
$formTwo->addInput('second_checkbox', 'Are you really cool?', 'checkbox');
$formTwo->addSubmit('second_submit', 'Test me');

// All under this comment must be called
// after registration of all form's controls.

if ($formOne->wasSubmitted()) {
	$submittedForm = $formOne;
} elseif ($formTwo->wasSubmitted()) {
	$submittedForm = $formTwo;
}

// If any form was submitted at all
if (!empty($submittedForm)) {

	// Get form's values...
	if ($submittedValues = $submittedForm->getValues()) {

		// ...and echo informatino about the submitted form
		echo sprintf("<h2>Form '%s' data</h2>", $submittedForm->getName());
		foreach ($submittedValues as $name => $value) {
			echo sprintf("<b>%s</b>: %s<br>", $name, print_r($value, true));
		}

		echo "<hr>";

	}
}

?>

<h1>Cool form page title</h1>

<h2>First form</h2>
<div><?php $formOne->render(); ?></div>

<h2>Second form</h2>
<div><?php $formTwo->render(); ?></div>