diff --git a/docs/en/02_Developer_Guides/03_Forms/00_Introduction.md b/docs/en/02_Developer_Guides/03_Forms/00_Introduction.md
index fcb6952fafa..a2d033127c4 100644
--- a/docs/en/02_Developer_Guides/03_Forms/00_Introduction.md
+++ b/docs/en/02_Developer_Guides/03_Forms/00_Introduction.md
@@ -332,6 +332,8 @@ class PageController extends ContentController
 
 ```
 
+See [how_tos/handle_nested_data](How to: Handle nested form data) for more advanced use cases.
+
 ## Validation
 
 Form validation is handled by the [Validator](api:SilverStripe\Forms\Validator) class and the `validator` property on the `Form` object. The validator 
diff --git a/docs/en/02_Developer_Guides/03_Forms/How_Tos/06_Handle_Nested_data.md b/docs/en/02_Developer_Guides/03_Forms/How_Tos/06_Handle_Nested_data.md
new file mode 100644
index 00000000000..e9a6ea15e81
--- /dev/null
+++ b/docs/en/02_Developer_Guides/03_Forms/How_Tos/06_Handle_Nested_data.md
@@ -0,0 +1,279 @@
+---
+title: How to handle nested data in forms
+summary: Forms can save into arrays, including has_one relations
+iconBrand: wpforms
+---
+
+# How to: Save nested data
+
+## Overview
+
+Forms often save into fields `DataObject` records, through [Form::saveInto()](api:Form::saveInto()).
+There are a number of ways to save nested data into those records, including their relationships.
+
+Let's take the following data structure, and walk through different approaches.
+
+```php
+<?php
+use SilverStripe\ORM\DataObject;
+
+class Player extends DataObject
+{
+    private static $db = [
+        'Name' => 'Varchar',
+    ];
+
+    private static $has_one = [
+        'HometownTeam' => Team::class,
+    ];
+
+    private static $many_many = [
+        'Teams' => Team::class,
+    ];
+}
+```
+
+```
+<?php
+use SilverStripe\ORM\DataObject;
+
+class Team extends DataObject
+{
+    private static $db = [
+        'Name' => 'Varchar',
+    ];
+
+    private static $belongs_many_many = [
+        'Players' => Player::class,
+    ];
+}
+```
+
+## Form fields
+
+Some form fields like [MultiSelectField](api:MultiSelectField) and [CheckboxSetField](api:CheckboxSetField)
+support saving lists of identifiers into a relation. Naming the field by the relation name will
+trigger the form field to write into the relationship.
+
+Example: Select teams for an existing player
+
+```php
+<?php
+
+use SilverStripe\Control\Controller;
+use SilverStripe\Forms\CheckboxSetField;
+use SilverStripe\Forms\FieldList;
+use SilverStripe\Forms\Form;
+use SilverStripe\Forms\FormAction;
+use SilverStripe\Forms\HiddenField;
+use SilverStripe\Forms\RequiredFields;
+use SilverStripe\Forms\TextField;
+
+class MyController extends Controller
+{
+    private static $allowed_actions = ['Form'];
+
+    private static $url_segment = 'MyController';
+
+    public function Form()
+    {
+        $player = Player::get()->byID(1);
+        return Form::create(
+            $this,
+            'Form',
+            FieldList::create([
+                TextField::create('Name'),
+                CheckboxSetField::create('Teams')
+                    ->setSource(Team::get()->map()),
+                HiddenField::create('ID'),
+            ]),
+            FieldList::create([
+                FormAction::create('doSubmitForm', 'Submit')
+            ]),
+            RequiredFields::create([
+                'Name',
+                'Teams',
+                'ID',
+            ])
+        )->loadDataFrom($player);
+    }
+
+    public function doSubmitForm($data, $form)
+    {
+        $player = Player::get()->byID($data['ID']);
+
+        // Only works for updating existing records
+        if (!$player) {
+            return false;
+        }
+
+        // Check permissions for the current user.
+        if (!$player->canEdit()) {
+            return false;
+        }
+
+        // Automatically writes Teams() relationship
+        $form->saveInto($player);
+
+        $form->sessionMessage('Saved!', 'good');
+
+        return $this->redirectBack();
+    }
+}
+```
+
+
+## Dot notation
+
+For single record relationships (e.g. `has_one`),
+forms can automatically traverse into this relationship by using dot notation
+in the form field name. This also works with custom getters returning 
+`DataObject` instances. 
+
+Example: Update team name (via a `has_one` relationship) on an existing player.
+
+```php
+<?php
+
+use SilverStripe\Control\Controller;
+use SilverStripe\Forms\FieldList;
+use SilverStripe\Forms\Form;
+use SilverStripe\Forms\FormAction;
+use SilverStripe\Forms\HiddenField;
+use SilverStripe\Forms\RequiredFields;
+use SilverStripe\Forms\TextField;
+
+class MyController extends Controller
+{
+    private static $allowed_actions = ['Form'];
+
+    private static $url_segment = 'MyController';
+
+    public function Form()
+    {
+        return Form::create(
+            $this,
+            'Form',
+            FieldList::create([
+                TextField::create('Name'),
+                TextField::create('HometownTeam.Name'),
+                HiddenField::create('ID'),
+            ]),
+            FieldList::create([
+                FormAction::create('doSubmitForm', 'Submit')
+            ]),
+            RequiredFields::create([
+                'Name',
+                'HometownTeam.Name',
+                'ID',
+            ])
+        );
+    }
+
+    public function doSubmitForm($data, $form)
+    {
+        $player = Player::get()->byID($data['ID']);
+
+        // Only works for updating existing records
+        if (!$player) {
+            return false;
+        }
+
+        // Check permissions for the current user.
+        if (!$player->canEdit() || !$player->HometownTeam()->canEdit()) {
+            return false;
+        }
+
+        $form->saveInto($player);
+
+        // Write relationships *before* the original object
+        // to avoid changes being lost when flush() is called after write().
+        // CAUTION: This will create a new record if none is set on the relationship.
+        // This might or might not be desired behaviour.
+        $player->HometownTeam()->write();
+        $player->write();
+
+        $form->sessionMessage('Saved!', 'good');
+
+        return $this->redirectBack();
+    }
+}
+```
+
+## Array notation
+
+This is the most advanced technique, since it works with the form submission directly,
+rather than relying on form field logic. 
+
+Example: Create one or more new teams for existing player
+
+```
+<?php
+
+use SilverStripe\Control\Controller;
+use SilverStripe\Forms\FieldList;
+use SilverStripe\Forms\Form;
+use SilverStripe\Forms\FormAction;
+use SilverStripe\Forms\HiddenField;
+use SilverStripe\Forms\RequiredFields;
+use SilverStripe\Forms\TextField;
+
+class MyController extends Controller
+{
+    private static $allowed_actions = ['Form'];
+
+    private static $url_segment = 'MyController';
+
+    public function Form()
+    {
+        $player = Player::get()->byID(1);
+        return Form::create(
+            $this,
+            'Form',
+            FieldList::create([
+                TextField::create('Name'),
+                // The UI could duplicate this field to allow creating multiple fields
+                TextField::create('NewTeams[]', 'New Teams'),
+                HiddenField::create('ID'),
+            ]),
+            FieldList::create([
+                FormAction::create('doSubmitForm', 'Submit')
+            ]),
+            RequiredFields::create([
+                'Name',
+                'MyTeams[]',
+                'ID',
+            ])
+        )->loadDataFrom($player);
+    }
+
+    public function doSubmitForm($data, $form)
+    {
+        $player = Player::get()->byID($data['ID']);
+
+        // Only works for updating existing records
+        if (!$player) {
+            return false;
+        }
+
+        // Check permissions for the current user.
+        // if (!$player->canEdit()) {
+        //     return false;
+        // }
+
+        $form->saveInto($player);
+
+        // Manually create teams based on provided data
+        foreach ($data['NewTeams'] as $teamName) {
+            // Caution: Requires data validation on model
+            $team = Team::create()->update(['Name' => $teamName]);
+            $team->write();
+            $player->Teams()->add($team);
+        }
+
+        $form->sessionMessage('Saved!', 'good');
+
+        return $this->redirectBack();
+    }
+}
+```
diff --git a/docs/en/04_Changelogs/4.9.0.md b/docs/en/04_Changelogs/4.9.0.md
new file mode 100644
index 00000000000..ef299090671
--- /dev/null
+++ b/docs/en/04_Changelogs/4.9.0.md
@@ -0,0 +1,6 @@
+# 4.9.0 (Unreleased)
+
+
+## New features
+
+* [Dot notation support in form fields](https://github.com/silverstripe/silverstripe-framework/pull/9192): Save directly into nested has_one relationships (see [docs](/developer_guides/forms/how_tos/handle_nested_data)).
diff --git a/src/Forms/FieldList.php b/src/Forms/FieldList.php
index 5ec25798a04..1044b64b30e 100644
--- a/src/Forms/FieldList.php
+++ b/src/Forms/FieldList.php
@@ -511,6 +511,7 @@ public function findOrMakeTab($tabName, $title = null)
      */
     public function fieldByName($name)
     {
+        $fullName = $name;
         if (strpos($name, '.') !== false) {
             list($name, $remainder) = explode('.', $name, 2);
         } else {
@@ -518,7 +519,9 @@ public function fieldByName($name)
         }
 
         foreach ($this as $child) {
-            if (trim($name) == trim($child->getName()) || $name == $child->id) {
+            if (trim($fullName) == trim($child->getName()) || $fullName == $child->id) {
+                return $child;
+            } elseif (trim($name) == trim($child->getName()) || $name == $child->id) {
                 if ($remainder) {
                     if ($child instanceof CompositeField) {
                         return $child->fieldByName($remainder);
diff --git a/src/Forms/Form.php b/src/Forms/Form.php
index 1d351695417..c35561d23f7 100644
--- a/src/Forms/Form.php
+++ b/src/Forms/Form.php
@@ -1462,19 +1462,39 @@ 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) {
+                    $exists = (
+                        $data->hasMethod('relField')
+                    );
+                    try {
+                        $val = $data->relField($name);
+                    } catch (\LogicException $e) {
+                        // There's no other way to tell whether the relation actually exists
+                        $exists = false;
+                    }
+                // 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($data)) {
                 if (array_key_exists($name, $data)) {
                     $exists = true;
                     $val = $data[$name];
+                // PHP turns the '.'s in POST vars into '_'s
+                } elseif (array_key_exists($altName = str_replace('.', '_', $name), $data)) {
+                    $exists = true;
+                    $val = $data[$altName];
                 } elseif (preg_match_all('/(.*)\[(.*)\]/U', $name, $matches)) {
                     // If field is in array-notation we need to access nested data
                     //discard first match which is just the whole string
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());
         }
     }
 
diff --git a/src/Forms/FormTemplateHelper.php b/src/Forms/FormTemplateHelper.php
index 227e248ed3f..a487ac44aff 100644
--- a/src/Forms/FormTemplateHelper.php
+++ b/src/Forms/FormTemplateHelper.php
@@ -61,14 +61,17 @@ public function generateFieldHolderID($field)
      */
     public function generateFieldID($field)
     {
+        // Don't include '.'s in IDs, they confused JavaScript
+        $name = str_replace('.', '_', $field->getName());
+
         if ($form = $field->getForm()) {
             return sprintf(
                 "%s_%s",
                 $this->generateFormID($form),
-                Convert::raw2htmlid($field->getName())
+                Convert::raw2htmlid($name)
             );
         }
 
-        return Convert::raw2htmlid($field->getName());
+        return Convert::raw2htmlid($name);
     }
 }
diff --git a/src/ORM/DataObject.php b/src/ORM/DataObject.php
index 0d0910aeb05..e67fc8201c5 100644
--- a/src/ORM/DataObject.php
+++ b/src/ORM/DataObject.php
@@ -1844,6 +1844,11 @@ public function getComponent($componentName)
             return $this->components[$componentName];
         }
 
+        // The join object can be returned as a component, named for its alias
+        if (isset($this->record[$componentName]) && $this->record[$componentName] === $this->joinRecord) {
+            return $this->record[$componentName];
+        }
+
         $schema = static::getSchema();
         if ($class = $schema->hasOneComponent(static::class, $componentName)) {
             $joinField = $componentName . 'ID';
diff --git a/tests/php/Forms/FormTest.php b/tests/php/Forms/FormTest.php
index b31a4a25437..8ee42df4bb1 100644
--- a/tests/php/Forms/FormTest.php
+++ b/tests/php/Forms/FormTest.php
@@ -88,7 +88,8 @@ public function testLoadDataFromRequest()
                 new TextField('key1'),
                 new TextField('namespace[key2]'),
                 new TextField('namespace[key3][key4]'),
-                new TextField('othernamespace[key5][key6][key7]')
+                new TextField('othernamespace[key5][key6][key7]'),
+                new TextField('dot.field')
             ),
             new FieldList()
         );
@@ -108,7 +109,9 @@ public function testLoadDataFromRequest()
                         'key7' => 'val7'
                     ]
                 ]
-            ]
+            ],
+            'dot.field' => 'dot.field val'
+
         ];
 
         $form->loadDataFrom($requestData);
@@ -118,6 +121,7 @@ public function testLoadDataFromRequest()
         $this->assertEquals('val2', $fields->fieldByName('namespace[key2]')->Value());
         $this->assertEquals('val4', $fields->fieldByName('namespace[key3][key4]')->Value());
         $this->assertEquals('val7', $fields->fieldByName('othernamespace[key5][key6][key7]')->Value());
+        $this->assertEquals('dot.field val', $fields->fieldByName('dot.field')->Value());
     }
 
     public function testSubmitReadonlyFields()
@@ -186,7 +190,8 @@ public function testLoadDataFromObject()
                 new TextField('Name'), // appears in both Player and Team
                 new TextareaField('Biography'),
                 new DateField('Birthday'),
-                new NumericField('BirthdayYear') // dynamic property
+                new NumericField('BirthdayYear'), // dynamic property
+                new TextField('FavouriteTeam.Name') // dot syntax
             ),
             new FieldList()
         );
@@ -200,6 +205,7 @@ public function testLoadDataFromObject()
                 'Biography' => 'Bio 1',
                 'Birthday' => '1982-01-01',
                 'BirthdayYear' => '1982',
+                'FavouriteTeam.Name' => 'Team 1',
             ],
             'LoadDataFrom() loads simple fields and dynamic getters'
         );
@@ -213,6 +219,7 @@ public function testLoadDataFromObject()
                 'Biography' => null,
                 'Birthday' => null,
                 'BirthdayYear' => 0,
+                'FavouriteTeam.Name' => null,
             ],
             'LoadNonBlankDataFrom() loads only fields with values, and doesnt overwrite existing values'
         );
@@ -229,6 +236,7 @@ public function testLoadDataFromClearMissingFields()
                 new TextareaField('Biography'),
                 new DateField('Birthday'),
                 new NumericField('BirthdayYear'), // dynamic property
+                new TextField('FavouriteTeam.Name'), // dot syntax
                 $unrelatedField = new TextField('UnrelatedFormField')
                 //new CheckboxSetField('Teams') // relation editing
             ),
@@ -245,6 +253,7 @@ public function testLoadDataFromClearMissingFields()
                 'Biography' => 'Bio 1',
                 'Birthday' => '1982-01-01',
                 'BirthdayYear' => '1982',
+                'FavouriteTeam.Name' => 'Team 1',
                 'UnrelatedFormField' => 'random value',
             ],
             'LoadDataFrom() doesnt overwrite fields not found in the object'
@@ -261,6 +270,7 @@ public function testLoadDataFromClearMissingFields()
                 'Biography' => '',
                 'Birthday' => '',
                 'BirthdayYear' => 0,
+                'FavouriteTeam.Name' => null,
                 'UnrelatedFormField' => null,
             ],
             'LoadDataFrom() overwrites fields not found in the object with $clearMissingFields=true'