NEW LinkFieldController to handle FormSchema

_config.php

@@ -5,5 +5,4 @@
 
 // Avoid creating global variables
 call_user_func(function () {
-
 });

src/Controllers/LinkFieldController.php

@@ -0,0 +1,137 @@
+<?php
+
+namespace SilverStripe\LinkField\Controllers;
+
+use SilverStripe\Admin\LeftAndMain;
+use SilverStripe\Control\HTTPRequest;
+use SilverStripe\Control\HTTPResponse;
+use SilverStripe\Core\Injector\Injector;
+use SilverStripe\LinkField\Form\FormFactory;
+use SilverStripe\Forms\Form;
+use SilverStripe\LinkField\Models\Link;
+use SilverStripe\Security\SecurityToken;
+use SilverStripe\ORM\ValidationResult;
+
+class LinkFieldController extends LeftAndMain
+{
+    private static $url_segment = 'linkfield';
+
+    // copying ElementalAreaController
+    private static $url_handlers = [
+        // API access points with structured data
+        'POST api/saveForm/$ID' => 'apiSaveForm',
+        # '$FormName/field/$FieldName' => 'formAction', // do we need this?
+    ];
+
+    /**
+     * Routed to be LeftAndMain::schema()
+     * /admin/linkfield/schema/linkForm/<linkID>
+     *
+     * Adapted from ElementalAreaController::getElementForm()
+     *
+     * @param int $elementID -- TODO not sure if this is required or not
+     * @return Form
+     */
+    public function getLinkForm(int $linkID): Form
+    {
+        $formFactory = FormFactory::create();
+
+        // this is a hackish way to get the correct DataObject type, I'm not sure what the clean method is
+        $obj = Link::get()->byID($linkID);
+        if ($obj && $obj->exists()) {
+            $className = $obj->ClassName;
+            $obj = $className::get()->byID($linkID);
+        } else {
+            $obj = Link::create();
+        }
+
+        /** @var Form $form */
+        $form = $formFactory->getForm($this, "LinkForm_$linkID", ['Record' => $obj]);
+        $form->addExtraClass('link-editor-editform__form');
+
+        if (!$obj->canEdit()) {
+            $form->makeReadonly();
+        }
+
+
+        return $form;
+    }
+
+    /**
+     * Code adapted from https://github.com/silverstripe/silverstripe-elemental/pull/1113/files#diff-942115e4b8f6030e4d72ebc2b3a0772ec65e5dfcd08fbd0e677c70d1231daf28R189
+     *
+     * Save an inline edit form for a Link
+     */
+    public function apiSaveForm(HTTPRequest $request): HTTPResponse
+    {
+        $id = $this->param('ID'); // $this->urlParams['ID']
+        // Validate required input data
+        if (!$id) {
+            $this->jsonError(400);
+        }
+
+        $data = $request->postVars();
+        // $data = json_decode($request->getBody(), true);
+        if (empty($data)) {
+            $this->jsonError(400);
+        }
+
+        // Check security token - TODO have temporarily disabled for easier dev
+        if (false) {
+            if (!SecurityToken::inst()->checkRequest($request)) {
+                $this->jsonError(400);
+            }
+        }
+
+        /** @var BaseElement $element */
+        $link = Link::get()->byID($id);
+        // Ensure the element can be edited by the current user
+        if (!$link || !$link->canEdit()) {
+            $this->jsonError(403);
+        }
+
+        // get form and populate it with POSTed data
+        $form = $this->getLinkForm($id);
+        $form->loadDataFrom($data);
+
+        // validate the Form
+        $validationResult = $form->validationResult();
+
+        // validate the DataObject
+        $element->updateFromFormData($data);
+        $validationResult->combineAnd($element->validate());
+
+        // handle validation failure and sent json formschema as response
+        if (!$validationResult->isValid()) {
+            // add headers to the request here so you don't need to do it in the client
+            // in the future I'd like these be the default response from formschema if
+            // the header wasn't defined
+            $request->addHeader('X-Formschema-Request', 'auto,schema,state,errors');
+            // generate schema response
+            $url = $this->getRequest()->getURL(); // admin/elemntal-area/api/saveForm/3
+            $response = $this->getSchemaResponse($url, $form, $validationResult);
+            // returning a 400 means that FormBuilder.js::handleSubmit() submitFn()
+            // that will end up in the catch() .. throw error block and the error
+            // will just end up in the javascript console
+            // $response->setStatusCode(400);
+            //
+            // return a 200 for now just to get things to work even though it's
+            // clearly the wrong code. Will require a PR to admin to fix this
+            $response->setStatusCode(200);
+            return $response;
+        }
+
+        $updated = false;
+        if ($element->isChanged()) {
+            $element->write();
+            // Track changes so we can return to the client
+            $updated = true;
+        }
+
+        // create and send success json response
+        return HTTPResponse::create(json_encode([
+            'status' => 'success',
+            'updated' => $updated,
+        ]))->addHeader('Content-Type', 'application/json');
+    }
+}