Improve the default LoginForm

- has the fields and actions extracted to a separate method, so it's more easily overridable
- Moved the global variable $_REQUEST to getting the info from the controller
- Updated string variables to `::class`
- Updated RequiredFields to be set in the YML, so it's overridable/updatable from either Config or code

_config/security.yml

@@ -0,0 +1,4 @@
+SilverStripe\Security\MemberLoginForm:
+  required_fields:
+    - Email
+    - Password

src/Security/Authenticator.php

@@ -22,7 +22,7 @@ abstract class Authenticator extends Object
      *
      * @var array
      */
-    private static $authenticators = array('SilverStripe\\Security\\MemberAuthenticator');
+    private static $authenticators = array(MemberAuthenticator::class);
 
     /**
      * Used to influence the order of authenticators on the login-screen
@@ -30,7 +30,7 @@ abstract class Authenticator extends Object
      *
      * @var string
      */
-    private static $default_authenticator = 'SilverStripe\\Security\\MemberAuthenticator';
+    private static $default_authenticator = MemberAuthenticator::class;
 
 
     /**
@@ -113,7 +113,7 @@ abstract class Authenticator extends Object
             return false;
         }
 
-        if (is_subclass_of($authenticator, 'SilverStripe\\Security\\Authenticator') == false) {
+        if (is_subclass_of($authenticator, self::class) == false) {
             return false;
         }
 

src/Security/MemberLoginForm.php

@@ -35,6 +35,12 @@ class MemberLoginForm extends LoginForm
      */
     public $loggedInAsField = 'FirstName';
 
+    /**
+     * Required fields for validation
+     * @var array
+     */
+    private static $required_fields;
+
     /**
      * Constructor
      *
@@ -69,8 +75,8 @@ class MemberLoginForm extends LoginForm
             Requirements::css($customCSS);
         }
 
-        if (isset($_REQUEST['BackURL'])) {
-            $backURL = $_REQUEST['BackURL'];
+        if ($controller->request->getVar('BackURL')) {
+            $backURL = $controller->request->getVar('BackURL');
         } else {
             $backURL = Session::get('BackURL');
         }
@@ -84,45 +90,10 @@ class MemberLoginForm extends LoginForm
             );
         } else {
             if (!$fields) {
-                $label = Member::singleton()->fieldLabel(Member::config()->unique_identifier_field);
-                $fields = FieldList::create(
-                    HiddenField::create("AuthenticationMethod", null, $this->authenticator_class, $this),
-                    // Regardless of what the unique identifer field is (usually 'Email'), it will be held in the
-                    // 'Email' value, below:
-                    $emailField = TextField::create("Email", $label, null, null, $this),
-                    PasswordField::create("Password", _t('Member.PASSWORD', 'Password'))
-                );
-                if (Security::config()->remember_username) {
-                    $emailField->setValue(Session::get('SessionForms.MemberLoginForm.Email'));
-                } else {
-                    // Some browsers won't respect this attribute unless it's added to the form
-                    $this->setAttribute('autocomplete', 'off');
-                    $emailField->setAttribute('autocomplete', 'off');
-                }
-                if (Security::config()->autologin_enabled) {
-                    $fields->push(
-                        CheckboxField::create(
-                            "Remember",
-                            _t('Member.KEEPMESIGNEDIN', "Keep me signed in")
-                        )->setAttribute(
-                            'title',
-                            sprintf(
-                                _t('Member.REMEMBERME', "Remember me next time? (for %d days on this device)"),
-                                RememberLoginHash::config()->uninherited('token_expiry_days')
-                            )
-                        )
-                    );
-                }
+                $fields = $this->getFormFields();
             }
             if (!$actions) {
-                $actions = FieldList::create(
-                    FormAction::create('dologin', _t('Member.BUTTONLOGIN', "Log in")),
-                    LiteralField::create(
-                        'forgotPassword',
-                        '<p id="ForgotPassword"><a href="' . Security::lost_password_url() . '">'
-                        . _t('Member.BUTTONLOSTPASSWORD', "I've lost my password") . '</a></p>'
-                    )
-                );
+                $actions = $this->getFormActions();
             }
         }
 
@@ -135,16 +106,69 @@ class MemberLoginForm extends LoginForm
 
         parent::__construct($controller, $name, $fields, $actions);
 
-        $this->setValidator(RequiredFields::create('Email', 'Password'));
+        $this->setValidator(RequiredFields::create(self::config()->get('required_fields')));
+    }
 
-        // Focus on the email input when the page is loaded
-        $js = <<<JS
-			(function() {
-				var el = document.getElementById("MemberLoginForm_LoginForm_Email");
-				if(el && el.focus && (typeof jQuery == 'undefined' || jQuery(el).is(':visible'))) el.focus();
-			})();
-JS;
-        Requirements::customScript($js, 'MemberLoginFormFieldFocus');
+    /**
+     * Build the FieldList for the login form
+     *
+     * @return FieldList
+     */
+    protected function getFormFields()
+    {
+        $label = Member::singleton()->fieldLabel(Member::config()->unique_identifier_field);
+        $fields = FieldList::create(
+            HiddenField::create("AuthenticationMethod", null, $this->authenticator_class, $this),
+            // Regardless of what the unique identifer field is (usually 'Email'), it will be held in the
+            // 'Email' value, below:
+            // @todo Rename the field to a more generic covering name
+            $emailField = TextField::create("Email", $label, null, null, $this),
+            PasswordField::create("Password", _t('Member.PASSWORD', 'Password'))
+        );
+        $emailField->setAttribute('autofocus', 'true');
+
+        if (Security::config()->remember_username) {
+            $emailField->setValue(Session::get('SessionForms.MemberLoginForm.Email'));
+        } else {
+            // Some browsers won't respect this attribute unless it's added to the form
+            $this->setAttribute('autocomplete', 'off');
+            $emailField->setAttribute('autocomplete', 'off');
+        }
+        if (Security::config()->autologin_enabled) {
+            $fields->push(
+                CheckboxField::create(
+                    "Remember",
+                    _t('Member.KEEPMESIGNEDIN', "Keep me signed in")
+                )->setAttribute(
+                    'title',
+                    sprintf(
+                        _t('Member.REMEMBERME', "Remember me next time? (for %d days on this device)"),
+                        RememberLoginHash::config()->uninherited('token_expiry_days')
+                    )
+                )
+            );
+        }
+
+        return $fields;
+    }
+
+    /**
+     * Build default login form action FieldList
+     *
+     * @return FieldList
+     */
+    protected function getFormActions()
+    {
+        $actions = FieldList::create(
+            FormAction::create('dologin', _t('Member.BUTTONLOGIN', "Log in")),
+            LiteralField::create(
+                'forgotPassword',
+                '<p id="ForgotPassword"><a href="' . Security::lost_password_url() . '">'
+                . _t('Member.BUTTONLOSTPASSWORD', "I've lost my password") . '</a></p>'
+            )
+        );
+
+        return $actions;
     }
 
     public function restoreFormState()