FIX Don't assume searchableFields() exists in gridfield filter

src/Forms/GridField/GridFieldFilterHeader.php

@@ -6,6 +6,7 @@
 use SilverStripe\Admin\LeftAndMain;
 use SilverStripe\Control\Controller;
 use SilverStripe\Control\HTTPResponse;
+use SilverStripe\Core\ClassInfo;
 use SilverStripe\Core\Config\Config;
 use SilverStripe\Core\Convert;
 use SilverStripe\Dev\Deprecation;
@@ -258,20 +259,36 @@ public function canFilterAnyColumns($gridField)
             return false;
         }
         $modelClass = $gridField->getModelClass();
-        // note: searchableFields() will return summary_fields if there are no searchable_fields on the model
-        $searchableFields = array_keys($modelClass::singleton()->searchableFields());
-        $summaryFields = array_keys($modelClass::singleton()->summaryFields());
-        sort($searchableFields);
-        sort($summaryFields);
-        // searchable_fields has been explictily defined i.e. searchableFields() is not falling back to summary_fields
-        if ($searchableFields !== $summaryFields) {
-            return true;
-        }
-        // we have fallen back to summary_fields, check they are filterable
-        foreach ($searchableFields as $searchableField) {
-            if ($list->canFilterBy($searchableField)) {
+        $singleton = singleton($modelClass);
+        if (ClassInfo::hasMethod($singleton, 'summaryFields')
+            && ClassInfo::hasMethod($singleton, 'searchableFields')
+        ) {
+            // note: searchableFields() will return summary_fields if there are no searchable_fields on the model
+            $searchableFields = array_keys($singleton->searchableFields());
+            $summaryFields = array_keys($singleton->summaryFields());
+            sort($searchableFields);
+            sort($summaryFields);
+            // searchable_fields has been explictily defined i.e. searchableFields() is not falling back to summary_fields
+            if ($searchableFields !== $summaryFields) {
                 return true;
             }
+            // we have fallen back to summary_fields, check they are filterable
+            foreach ($searchableFields as $searchableField) {
+                if ($list->canFilterBy($searchableField)) {
+                    return true;
+                }
+            }
+        } else {
+            // Allows non-DataObject classes to be used with this component
+            $columns = $gridField->getColumns();
+            foreach ($columns as $columnField) {
+                $metadata = $gridField->getColumnMetadata($columnField);
+                $title = $metadata['title'];
+
+                if ($title && $list->canFilterBy($columnField)) {
+                    return true;
+                }
+            }
         }
         return false;
     }

tests/php/Forms/GridField/GridFieldFilterHeaderTest.php

@@ -8,13 +8,16 @@
 use SilverStripe\Forms\FieldList;
 use SilverStripe\Forms\Form;
 use SilverStripe\Forms\GridField\GridField;
+use SilverStripe\Forms\GridField\GridFieldConfig;
 use SilverStripe\Forms\GridField\GridFieldConfig_RecordEditor;
 use SilverStripe\Forms\GridField\GridFieldFilterHeader;
 use SilverStripe\Forms\Tests\GridField\GridFieldFilterHeaderTest\Cheerleader;
 use SilverStripe\Forms\Tests\GridField\GridFieldFilterHeaderTest\CheerleaderHat;
 use SilverStripe\Forms\Tests\GridField\GridFieldFilterHeaderTest\Mom;
+use SilverStripe\Forms\Tests\GridField\GridFieldFilterHeaderTest\NonDataObject;
 use SilverStripe\Forms\Tests\GridField\GridFieldFilterHeaderTest\Team;
 use SilverStripe\Forms\Tests\GridField\GridFieldFilterHeaderTest\TeamGroup;
+use SilverStripe\ORM\ArrayList;
 use SilverStripe\ORM\DataList;
 use SilverStripe\ORM\DataObject;
 
@@ -187,7 +190,7 @@ public function testCanFilterAnyColumns()
     {
         $gridField = $this->gridField;
         $filterHeader = $gridField->getConfig()->getComponentByType(GridFieldFilterHeader::class);
-        
+
         // test that you can filter by something if searchable_fields is not defined
         // silverstripe will scaffold db columns that are in the gridfield to be
         // searchable by default
@@ -208,4 +211,33 @@ public function testCanFilterAnyColumns()
         Config::modify()->set(Team::class, 'summary_fields', ['MySummaryField']);
         $this->assertFalse($filterHeader->canFilterAnyColumns($gridField));
     }
+
+    public function testCanFilterAnyColumnsNonDataObject()
+    {
+        $list = new ArrayList([
+            new NonDataObject([]),
+        ]);
+        $config = GridFieldConfig::create()->addComponent(new GridFieldFilterHeader());
+        $gridField = new GridField('testfield', 'testfield', $list, $config);
+        $form = new Form(null, 'Form', new FieldList([$gridField]), new FieldList());
+        /** @var GridFieldFilterHeader $component */
+        $component = $gridField->getConfig()->getComponentByType(GridFieldFilterHeader::class);
+
+        $this->assertFalse($component->canFilterAnyColumns($gridField));
+    }
+
+    public function testRenderHeadersNonDataObject()
+    {
+        $list = new ArrayList([
+            new NonDataObject([]),
+        ]);
+        $config = GridFieldConfig::create()->addComponent(new GridFieldFilterHeader());
+        $gridField = new GridField('testfield', 'testfield', $list, $config);
+        $form = new Form(null, 'Form', new FieldList([$gridField]), new FieldList());
+        /** @var GridFieldFilterHeader $component */
+        $component = $gridField->getConfig()->getComponentByType(GridFieldFilterHeader::class);
+        $htmlFragment = $component->getHTMLFragments($gridField);
+
+        $this->assertNull($htmlFragment);
+    }
 }

tests/php/Forms/GridField/GridFieldFilterHeaderTest/NonDataObject.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace SilverStripe\Forms\Tests\GridField\GridFieldFilterHeaderTest;
+
+use SilverStripe\Dev\TestOnly;
+use SilverStripe\View\ArrayData;
+
+class NonDataObject extends ArrayData implements TestOnly
+{
+    public function summaryFields()
+    {
+        return ['Title' => 'Title'];
+    }
+}