From b407f26e024c9f3d10fc9c0ea14fe2649c01e1e2 Mon Sep 17 00:00:00 2001
From: Luke Towers <github@luketowers.ca>
Date: Thu, 10 Sep 2020 12:12:46 -0600
Subject: [PATCH] Add support for \Path\To\Class::staticMethodName for defining
 field options.

Related: https://github.com/octobercms/library/commit/95d0b61a298d0933dd2117967481e00b416029c4
---
 modules/backend/lang/en/lang.php |  1 +
 modules/backend/widgets/Form.php | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/modules/backend/lang/en/lang.php b/modules/backend/lang/en/lang.php
index 368664c63..230e744a4 100644
--- a/modules/backend/lang/en/lang.php
+++ b/modules/backend/lang/en/lang.php
@@ -9,6 +9,7 @@ return [
         'invalid_type' => 'Invalid field type used :type.',
         'options_method_invalid_model' => "The attribute ':field' does not resolve to a valid model. Try specifying the options method for model class :model explicitly.",
         'options_method_not_exists' => "The model class :model must define a method :method() returning options for the ':field' form field.",
+        'options_static_method_invalid_value' => "The static method ':method()' on :class did not return a valid options array.",
         'colors_method_not_exists' => "The model class :model must define a method :method() returning html color HEX codes for the ':field' form field.",
     ],
     'widget' => [
diff --git a/modules/backend/widgets/Form.php b/modules/backend/widgets/Form.php
index 5b79a6c75..c2acbb2a3 100644
--- a/modules/backend/widgets/Form.php
+++ b/modules/backend/widgets/Form.php
@@ -1283,6 +1283,7 @@ class Form extends WidgetBase
     {
         /*
          * Advanced usage, supplied options are callable
+         * [\Path\To\Class, methodName]
          */
         if (is_array($fieldOptions) && is_callable($fieldOptions)) {
             $fieldOptions = call_user_func($fieldOptions, $this, $field);
@@ -1328,6 +1329,22 @@ class Form extends WidgetBase
          * Field options are an explicit method reference
          */
         elseif (is_string($fieldOptions)) {
+            // \Path\To\Class::staticMethodOptions
+            if (str_contains($fieldOptions, '::')) {
+                $options = explode('::', $fieldOptions);
+                if (count($options) === 2 && class_exists($options[0]) && method_exists($options[0], $options[1])) {
+                    $result = $options[0]::{$options[1]}();
+                    if (!is_array($result)) {
+                        throw new ApplicationException(Lang::get('backend::lang.field.options_static_method_invalid_value', [
+                            'class' => $options[0],
+                            'method' => $options[1]
+                        ]));
+                    }
+                    return $result;
+                }
+            }
+
+            // $model->{$fieldOptions}()
             if (!$this->objectMethodExists($this->model, $fieldOptions)) {
                 throw new ApplicationException(Lang::get('backend::lang.field.options_method_not_exists', [
                     'model'  => get_class($this->model),