From 02fb7c3b178f85b75365b0efb46ae8b25a204590 Mon Sep 17 00:00:00 2001
From: Sam Minnee <sam@silverstripe.com>
Date: Sat, 24 Aug 2019 16:28:09 +1200
Subject: [PATCH] NEW: Support dot syntax in form field names

This change adds support for these in a few places.

 - Form::saveInto($record)
 - Form::loadDataForm($record)
 - Form::loadDataForm($_POST)

Fixes https://github.com/silverstripe/silverstripe-framework/issues/9163
---
 src/Forms/Form.php      | 29 +++++++++++++++++++++--------
 src/Forms/FormField.php | 14 ++++++++++++--
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/src/Forms/Form.php b/src/Forms/Form.php
index 1d351695417..d9e0e91c172 100644
--- a/src/Forms/Form.php
+++ b/src/Forms/Form.php
@@ -1462,16 +1462,29 @@ public function loadDataFrom($data, $mergeStrategy = 0, $fieldList = null)
             $val = null;
 
             if (is_object($data)) {
-                $exists = (
-                    isset($data->$name) ||
-                    $data->hasMethod($name) ||
-                    ($data->hasMethod('hasField') && $data->hasField($name))
-                );
-
-                if ($exists) {
-                    $val = $data->__get($name);
+                // Allow dot-syntax traversal of has-one relations fields
+                if (strpos($name, '.') !== false && $data->hasMethod('relField')) {
+                    $val = $data->relField($name);
+                    $exists = true;
+
+                // Regular ViewableData access
+                } else {
+                    $exists = (
+                        isset($data->$name) ||
+                        $data->hasMethod($name) ||
+                        ($data->hasMethod('hasField') && $data->hasField($name))
+                    );
+
+                    if ($exists) {
+                        $val = $data->__get($name);
+                    }
                 }
+
+            // Regular array access. Note that dot-syntax not supported here
             } elseif (is_array($data)) {
+                // PHP turns the '.'s in POST vars into '_'s
+                $name = str_replace('.', '_', $name);
+
                 if (array_key_exists($name, $data)) {
                     $exists = true;
                     $val = $data[$name];
diff --git a/src/Forms/FormField.php b/src/Forms/FormField.php
index 9cad1e8df6c..d35871c3a94 100644
--- a/src/Forms/FormField.php
+++ b/src/Forms/FormField.php
@@ -469,8 +469,18 @@ public function Value()
      */
     public function saveInto(DataObjectInterface $record)
     {
-        if ($this->name) {
-            $record->setCastedField($this->name, $this->dataValue());
+        $component = $record;
+        $fieldName = $this->name;
+
+        // Allow for dot syntax
+        if (($pos = strrpos($this->name, '.')) !== false) {
+            $relation = substr($this->name, 0, $pos);
+            $fieldName = substr($this->name, $pos + 1);
+            $component = $record->relObject($relation);
+        }
+
+        if ($fieldName) {
+            $component->setCastedField($fieldName, $this->dataValue());
         }
     }