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Forms

HTML forms are in practice the most used way to communicate with a browser. 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 - Often submit buttons that executes actions.
Validators - Validate the whole form, see Form validation topic for more information.

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

Since forms need a URL, the HelloForm() method needs to be handled like any other controller action. In order to whitelist its access through URLs, we add it to the $allowed_actions array.

Form actions ("doSayHello") on the other hand should NOT be included here, 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 the Controller::$allowed_actions() to be sure that form submissions get through to the correct action.

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 and 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 fields allow the form object to be re-created after submission. It's vital that they are properly set - if you ever have problems with 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' 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 can 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 only do this if you've got a lot of presentation text, 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 of all, you need to create your form on it's own class, 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 customization:

:::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)
		</div>
		
		<div id="Email" class="field password">
			<label class="left" for="{$FormName}_Password">Password</label>
			$Fields.dataFieldByName(Password)
		</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. In order to influence the form rendering, overloading these two methods is a good start.

In addition, most form fields are rendered through SilverStripe templates, e.g. TextareaField is rendered via framework/templates/forms/TextareaField.ss.

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

FormField->setTemplate()
FormField->setFieldHolderTemplate()
FormField->getSmallFieldHolderTemplate()

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 surface, 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');

API Documentation

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

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