silverstripe-framework/docs/en/02_Developer_Guides/03_Forms/00_Forms.md

Forms

HTML forms are in practice the most used way to interact with a user. SilverStripe provides classes to generate and handle the actions and data from a form.

Overview

A fully implemented form in SilverStripe includes a couple of classes that individually have separate concerns.

• Controller — Takes care of assembling the form and receiving data from it.
• Form — Holds sets of fields, actions and validators.
• FormField — Fields that receive data or displays them, e.g input fields.
• FormActions — Buttons that execute actions.
• Validators — Validate the whole form.

Depending on your needs you can customize and override any of the above classes; the defaults, however, are often sufficient.

The Controller

Forms start at the controller. Here is a simple example on how to set up a form in a controller.

Page.php

:::php
class Page_Controller extends ContentController {
	
	private static $allowed_actions = array(
		'HelloForm'
	);
	
	// Template method
	public function HelloForm() {
		$fields = new FieldList();
		$actions = new FieldList(
			FormAction::create("doSayHello")->setTitle("Say hello")
		);
		$form = new Form($this, 'HelloForm', $fields, $actions);
		// Load the form with previously sent data
		$form->loadDataFrom($this->request->postVars());
		return $form;
	}
	
	public function doSayHello($data, Form $form) {
		// Do something with $data
		return $this->render();
	}
}

The name of the form ("HelloForm") is passed into the Form constructor as a second argument. It needs to match the method name.

Because forms need a URL, the HelloForm() method needs to be handled like any other controller action. To grant it access through URLs, we add it to the $allowed_actions array.

Form actions ("doSayHello"), on the other hand, should not be included in $allowed_actions; these are handled separately through Form->httpSubmission().

You can control access on form actions either by conditionally removing a FormAction from the form construction, or by defining $allowed_actions in your own Form class (more information in the "controllers" topic).

Page.ss

:::ss
<%-- place where you would like the form to show up --%>
<div>$HelloForm</div>

Be sure to add the Form name 'HelloForm' to your controller's $allowed_actions array to enable form submissions.

You'll notice that we've used a new notation for creating form fields, using `create()` instead of the `new` operator. These are functionally equivalent, but allows PHP to chain operations like `setTitle()` without assigning the field instance to a temporary variable. For in-depth information on the create syntax, see the [Injector](/reference/injector) documentation or the API documentation for `[api:Object]`::create().

The Form

Form is the base class of all forms in a SilverStripe application. Forms in your application can be created either by instantiating the Form class itself, or by subclassing it.

Instantiating a form

Creating a form is a matter of defining a method to represent that form. This method should return a form object. The constructor takes the following arguments:

• $controller: This must be an instance of the controller that contains the form, often $this.
• $name: This must be the name of the method on that controller that is called to return the form. The first two arguments allow the form object to be re-created after submission. It's vital that they be properly set—if you ever have problems with a form action handler not working, check that these values are correct.
• $fields: A [api:FieldList] containing [api:FormField] instances make up fields in the form.
• $actions: A [api:FieldList] containing the [api:FormAction] objects - the buttons at the bottom.
• $validator: An optional [api:Validator] for validation of the form.

Example:

:::php
// Controller action
public function MyCustomForm() {
	$fields = new FieldList(
		EmailField::create("Email"),
		PasswordField::create("Password")
	);
	$actions = new FieldList(FormAction::create("login")->setTitle("Log in"));
	return new Form($this, "MyCustomForm", $fields, $actions);
}

Subclassing a form

It's the responsibility of your subclass's constructor to call

:::php
parent::__construct()

with the right parameters. You may choose to take $fields and $actions as arguments if you wish, but $controller and $name must be passed—their values depend on where the form is instantiated.

:::php
class MyForm extends Form {
	public function __construct($controller, $name) {
		$fields = new FieldList(
			EmailField::create("Email"),
			PasswordField::create("Password")
		);
		$actions = new FieldList(FormAction::create("login")->setTitle("Log in"));
		
		parent::__construct($controller, $name, $fields, $actions);
	}
}

The real difference, however, is that you can then define your controller methods within the form class itself. This means that the form takes responsibilities from the controller and manage how to parse and use the form data.

Page.php

:::php
class Page_Controller extends ContentController {
	
	private static $allowed_actions = array(
		'HelloForm',
	);
	
	// Template method
	public function HelloForm() {
		return new MyForm($this, 'HelloForm');
	}
}

MyForm.php

:::php
class MyForm extends Form {

	public function __construct($controller, $name) {
		$fields = new FieldList(
			EmailField::create("Email"),
			PasswordField::create("Password")
		);

		$actions = new FieldList(FormAction::create("login")->setTitle("Log in"));
		
		parent::__construct($controller, $name, $fields, $actions);
	}
	
	public function login(array $data, Form $form) {
		// Authenticate the user and redirect the user somewhere
		Controller::curr()->redirectBack();
	}
}

The FormField classes

There are many classes extending [api:FormField]. There is a full overview at form field types.

Using Form Fields

To get these fields automatically rendered into a form element, all you need to do is create a new instance of the class, and add it to the FieldList of the form.

:::php
$form = new Form(
	$this, // controller
	"SignupForm", // form name
	new FieldList( // fields
		TextField::create("FirstName")->setTitle('First name'),
		TextField::create("Surname")->setTitle('Last name')->setMaxLength(50),
		EmailField::create("Email")->setTitle("Email address")->setAttribute('type', 'email')
	), 
	new FieldList( // actions
		FormAction::create("signup")->setTitle("Sign up")
	), 
	new RequiredFields( // validation
		"Email", "FirstName"
	)
);

Readonly

You can turn a form or individual fields into a readonly version. This is handy in the case of confirmation pages or when certain fields cannot be edited due to permissions.

Readonly on a Form

:::php
$myForm->makeReadonly();

Readonly on a FieldList

:::php
$myFieldList->makeReadonly();

Readonly on a FormField

:::php
$myReadonlyField = $myField->transform(new ReadonlyTransformation());
// shortcut
$myReadonlyField = $myField->performReadonlyTransformation();

Custom form templates

You can use a custom form template to render with, instead of Form.ss

It's recommended you do this only if you have a lot of presentation text or graphics that surround the form fields. This is better than defining those as LiteralField objects, as it doesn't clutter the data layer with presentation junk.

First you need to create your own form class extending Form; that way you can define a custom template using a forTemplate() method on your Form class.

:::php
class MyForm extends Form {

	public function __construct($controller, $name) {
		$fields = new FieldList(
			EmailField::create("Email"),
			PasswordField::create("Password")
		);

		$actions = new FieldList(FormAction::create("login")->setTitle("Log in"));
		parent::__construct($controller, $name, $fields, $actions);
	}
	
	public function login(array $data, Form $form) {
		// Do something with $data
		Controller::curr()->redirectBack();
	}
	
	public function forTemplate() {
		return $this->renderWith(array($this->class, 'Form'));
	}
}

MyForm->forTemplate() tells the [api:Form] class to render with a template of return value of $this->class, which in this case is MyForm. If the template doesn't exist, then it falls back to using Form.ss.

MyForm.ss should then be placed into your templates/Includes directory for your project. Here is an example of basic customisation, with two ways of presenting the field and its inline validation:

:::ss
<form $FormAttributes>
	<% if $Message %>
		<p id="{$FormName}_error" class="message $MessageType">$Message</p>
	<% else %>
		<p id="{$FormName}_error" class="message $MessageType" style="display: none"></p>
	<% end_if %>
	
	<fieldset>
		<div id="Email" class="field email">
			<label class="left" for="{$FormName}_Email">Email</label>
			$Fields.dataFieldByName(Email)
			<span id="{$FormName}_error" class="message $Fields.dataFieldByName(Email).MessageType">
				$Fields.dataFieldByName(Email).Message
			</span>
		</div>
		
		<div id="Email" class="field password">
			<label class="left" for="{$FormName}_Password">Password</label>
			<% with $Fields.dataFieldByName(Password) %>
				$field
				<% if $Message %>
					<p id="{$FormName}_error" class="message $MessageType">$Message</p>
				<% end_if %>
			<% end_with %>
		</div>
		
		$Fields.dataFieldByName(SecurityID)
	</fieldset>
	
	<% if $Actions %>
	<div class="Actions">
		<% loop $Actions %>$Field<% end_loop %>
	</div>
	<% end_if %>
</form>

$Fields.dataFieldByName(FirstName) will return the form control contents of Field() for the particular field object, in this case EmailField->Field() or PasswordField->Field() which returns an <input> element with specific markup for the type of field. Pass in the name of the field as the first parameter, as done above, to render it into the template.

To find more methods, have a look at the [api:Form] class and [api:FieldList] class as there is a lot of different methods of customising the form templates. An example is that you could use <% loop $Fields %> instead of specifying each field manually, as we've done above.

Custom form field templates

The easiest way to customize form fields is adding CSS classes and additional attributes.

:::php
$field = TextField::create('MyText')
	->addExtraClass('largeText');
	->setAttribute('data-validation-regex', '[\d]*');

Will be rendered as:

:::html
<input type="text" name="MyText" class="text largeText" id="MyForm_MyCustomForm_MyText" data-validation-regex="[\d]*">

Each form field is rendered into a form via the [FormField->FieldHolder()](api:FormField) method, which includes a container <div> as well as a <label> element (if applicable).

You can also render each field without these structural elements through the [FormField->Field()](api:FormField) method. To influence form rendering, overriding these two methods is a good start.

In addition, most form fields are rendered through SilverStripe templates; for example, TextareaField is rendered via framework/templates/forms/TextareaField.ss.

These templates can be overridden globally by placing a template with the same name in your mysite directory, or set on a form field instance via any of these methods:

• FormField->setTemplate()
• FormField->setFieldHolderTemplate()
• FormField->setSmallFieldHolderTemplate()

Caution: Not all FormFields consistently uses templates set by the above methods.

Securing forms against Cross-Site Request Forgery (CSRF)

SilverStripe tries to protect users against Cross-Site Request Forgery (CSRF) by adding a hidden SecurityID parameter to each form. See secure-development for details.

In addition, you should limit forms to the intended HTTP verb (mostly GET or POST) to further reduce attack exposure, by using [api:Form->setStrictFormMethodCheck()].

:::php
$myForm->setFormMethod('POST');
$myForm->setStrictFormMethodCheck(true);
$myForm->setFormMethod('POST', true); // alternative short notation

Remove existing fields

If you want to remove certain fields from your subclass:

:::php
class MyCustomForm extends MyForm {

	public function __construct($controller, $name) {
		parent::__construct($controller, $name);
		
		// remove a normal field
		$this->Fields()->removeByName('MyFieldName');
		
		// remove a field from a tab
		$this->Fields()->removeFieldFromTab('TabName', 'MyFieldName');
	}
}

Working with tabs

Adds a new text field called FavouriteColour next to the Content field in the CMS

:::php
$this->Fields()->addFieldToTab('Root.Content', new TextField('FavouriteColour'), 'Content');

Form Validation

SilverStripe provides PHP form validation out of the box, but doesn't come with any built-in JavaScript validation (the previously used Validator.js approach has been deprecated).

Required Fields

Validators are implemented as an argument to the [api:Form] constructor, and are subclasses of the abstract [api:Validator] base class. The only implementation that comes with SilverStripe is the [api:RequiredFields] class, which ensures that fields are filled out when the form is submitted.

:::php
public function Form() {
	$form = new Form($this, 'Form',
		new FieldList(
			new TextField('MyRequiredField'),
			new TextField('MyOptionalField')
		),
		new FieldList(
			new FormAction('submit', 'Submit form')
		),
		new RequiredFields(array('MyRequiredField'))
	);
	// Optional: Add a CSS class for custom styling
	$form->dataFieldByName('MyRequiredField')->addExtraClass('required');
	return $form;
}

Form Field Validation

Form fields are responsible for validating the data they process, through the [api:FormField->validate()] method. There are many fields for different purposes (see "form field types" for a full list).

Adding your own validation messages

In many cases, you want to add PHP validation that is more complex than validating the format or existence of a single form field input. For example, you might want to have dependent validation on a postcode which depends on the country you've selected in a different field.

There are two ways to go about this: attach a custom error message to a specific field, or a generic message to the whole form.

Example: Validate postcodes based on the selected country (on the controller).

:::php
class MyController extends Controller {
	private static $allowed_actions = array('Form');
	public function Form() {
		return Form::create($this, 'Form',
			new FieldList(
				new NumericField('Postcode'),
				new CountryDropdownField('Country')
			),
			new FieldList(
				new FormAction('submit', 'Submit form')
			),
			new RequiredFields(array('Country'))
		);
	}
	public function submit($data, $form) {
		// At this point, RequiredFields->validate() will have been called already,
		// so we can assume that the values exist.
		
		// German postcodes need to be five digits
		if($data['Country'] == 'de' && isset($data['Postcode']) && strlen($data['Postcode']) != 5) {
			$form->addErrorMessage('Postcode', 'Need five digits for German postcodes', 'bad');
			return $this->redirectBack();
		}
		
		// Global validation error (not specific to form field)
		if($data['Country'] == 'IR' && isset($data['Postcode']) && $data['Postcode']) {
			$form->sessionMessage("Ireland doesn't have postcodes!", 'bad');
			return $this->redirectBack();
		}
		
		// continue normal processing...
	}
}

JavaScript Validation

Although there are no built-in JavaScript validation handlers in SilverStripe, the FormField API is flexible enough to provide the information required in order to plug in custom libraries.

HTML5 attributes

HTML5 specifies some built-in form validations (source), which are evaluated by modern browsers without any need for JavaScript. SilverStripe supports this by allowing to set custom attributes on fields.

:::php
// Markup contains <input type="text" required />
TextField::create('MyText')->setAttribute('required', true);

// Markup contains <input type="url" pattern="https?://.+" />
TextField::create('MyText')
	->setAttribute('type', 'url')
	->setAttribute('pattern', 'https?://.+')

HTML5 metadata

In addition, HTML5 elements can contain custom data attributes with the data- prefix. These are general-purpose attributes, but can be used to hook in your own validation.

:::php
// Validate a specific date format (in PHP)
// Markup contains <input type="text" data-dateformat="dd.MM.yyyy" />
DateField::create('MyDate')->setConfig('dateformat', 'dd.MM.yyyy');

// Limit extensions on upload (in PHP)
// Markup contains <input type="file" data-allowed-extensions="jpg,jpeg,gif" />
$exts = array('jpg', 'jpeg', 'gif');
$fileField = FileField::create('MyFile');
$fileField->getValidator()->setAllowedExtensions($exts);
$fileField->setAttribute('data-allowed-extensions', implode(',', $exts));

Note that these examples don't have any effect on the client as such, but are just a starting point for custom validation with JavaScript.

Model Validation

An alternative (or additional) approach to validation is to place it directly on the model. SilverStripe provides a [api:DataObject->validate()] method for this purpose. Refer to the "datamodel" topic for more information.

Validation in the CMS

Since you're not creating the forms for editing CMS records, SilverStripe provides you with a getCMSValidator() method on your models to return a [api:Validator] instance.

:::php
class Page extends SiteTree {
	private static $db = array('MyRequiredField' => 'Text');
	
	public function getCMSValidator() {
		return new RequiredFields(array('MyRequiredField'));
	}
}

Subclassing Validator

To create your own validator, you need to subclass validator and define two methods:

• javascript() Should output a snippet of JavaScript that will get called to perform javascript validation.
• php($data) Should return true if the given data is valid, and call $this->validationError() if there were any errors.

Related

• Form Field Types
• MultiForm Module
• Model Validation with [api:DataObject->validate()]

API Documentation

• [api:Form]
• [api:FormField]
• [api:FieldList]
• [api:FormAction]