API Unify search filter functionality across the CMS

CMSMain had different search filter code paths than the grid field
search filter, and there was a lot of duplication of code. This commit
works alongside a commit in silverstripe/silverstripe-cms to unify those
code paths

Author: GuySartorelli

src/Forms/Form.php

@@ -308,7 +308,9 @@ public function __construct(
         }
 
         // Form error controls
-        $this->restoreFormState();
+        if ($controller) {
+            $this->restoreFormState();
+        }
 
         // Check if CSRF protection is enabled, either on the parent controller or from the default setting. Note that
         // method_exists() is used as some controllers (e.g. GroupTest) do not always extend from Object.
@@ -1790,6 +1792,21 @@ public function removeExtraClass($class)
         return $this;
     }
 
+    public function __clone(): void
+    {
+        $this->fields = clone $this->fields;
+        $this->actions = clone $this->actions;
+        if ($this->validator) {
+            $this->setValidator(clone $this->validator);
+        }
+        foreach ($this->fields as $field) {
+            $field->setForm($this);
+        }
+        foreach ($this->actions as $action) {
+            $action->setForm($this);
+        }
+    }
+
     public function debug(): string
     {
         $class = static::class;

src/Forms/FormRequestHandler.php

@@ -4,16 +4,15 @@
 
 use BadMethodCallException;
 use SilverStripe\Control\Controller;
-use SilverStripe\Control\Director;
 use SilverStripe\Control\HTTPRequest;
 use SilverStripe\Control\HTTPResponse;
 use SilverStripe\Control\HTTPResponse_Exception;
 use SilverStripe\Control\RequestHandler;
 use SilverStripe\Core\ClassInfo;
-use SilverStripe\Core\Convert;
 use SilverStripe\Core\Validation\ValidationResult;
 use SilverStripe\Model\List\SS_List;
 use SilverStripe\Core\Validation\ValidationException;
+use SilverStripe\Forms\Schema\FormSchema;
 
 class FormRequestHandler extends RequestHandler
 {
@@ -27,6 +26,7 @@ class FormRequestHandler extends RequestHandler
      * @var array
      */
     private static $allowed_actions = [
+        'getSchema',
         'handleField',
         'httpSubmission',
         'forTemplate',
@@ -37,6 +37,7 @@ class FormRequestHandler extends RequestHandler
      * @var array
      */
     private static $url_handlers = [
+        'GET schema' => 'getSchema',
         'field/$FieldName!' => 'handleField',
         'POST ' => 'httpSubmission',
         'GET ' => 'httpSubmission',
@@ -67,6 +68,18 @@ public function __construct(Form $form)
         }
     }
 
+    /**
+     * Gets a JSON schema representing a form.
+     */
+    public function getSchema(HTTPRequest $request): HTTPResponse
+    {
+        $schemaID = $request->getURL();
+        $parts = $request->getHeader(FormSchema::SCHEMA_HEADER);
+        $data = FormSchema::singleton()->getMultipartSchema($parts, $schemaID, $this->form);
+        $response = HTTPResponse::create(json_encode($data));
+        $response->addHeader('Content-Type', 'application/json');
+        return $response;
+    }
 
     /**
      * Get link for this form

src/Forms/GridField/GridField.php

@@ -275,8 +275,8 @@ public function performReadonlyTransformation()
         $hadEditButton = $copyConfig->getComponentByType(GridFieldEditButton::class) !== null;
 
         // get the whitelist for allowable readonly components
-        $allowedComponents = $this->getReadonlyComponents();
-        foreach ($this->getConfig()->getComponents() as $component) {
+        $allowedComponents = $copy->getReadonlyComponents();
+        foreach ($copy->getConfig()->getComponents() as $component) {
             // if a component doesn't exist, remove it from the readonly version.
             if (!in_array(get_class($component), $allowedComponents ?? [])) {
                 $copyConfig->removeComponent($component);
@@ -297,7 +297,7 @@ public function performReadonlyTransformation()
             }
         }
 
-        $copy->extend('afterPerformReadonlyTransformation', $this);
+        $copy->extend('afterPerformReadonlyTransformation', $copy);
 
         return $copy;
     }
@@ -1346,6 +1346,11 @@ public function saveInto(DataObjectInterface $record)
         }
     }
 
+    public function __clone(): void
+    {
+        $this->config = clone $this->config;
+    }
+
     /**
      * @param array $content
      *

src/Forms/GridField/GridFieldConfig.php

@@ -155,4 +155,13 @@ public function getComponentByType($type)
         }
         return null;
     }
+
+    public function __clone(): void
+    {
+        $components = $this->components;
+        $this->components = ArrayList::create();
+        foreach ($components as $component) {
+            $this->components->add(clone $component);
+        }
+    }
 }