/**
  * Returns the class name in the class hierarchy which contains a given
  * field column for a {@link DataObject}. If the field does not exist, this
  * will return null.
  *
  * @param string $candidateClass
  * @param string $fieldName
  * @return string
  */
 public function classForField($candidateClass, $fieldName)
 {
     // normalise class name
     $candidateClass = ClassInfo::class_name($candidateClass);
     if ($candidateClass === 'SilverStripe\\ORM\\DataObject') {
         return null;
     }
     // Short circuit for fixed fields
     $fixed = DataObject::config()->fixed_fields;
     if (isset($fixed[$fieldName])) {
         return $this->baseDataClass($candidateClass);
     }
     // Find regular field
     while ($candidateClass) {
         $fields = $this->databaseFields($candidateClass);
         if (isset($fields[$fieldName])) {
             return $candidateClass;
         }
         $candidateClass = get_parent_class($candidateClass);
     }
     return null;
 }
 /**
  * Gets the form fields as defined through the metadata
  * on {@link $obj} and the custom parameters passed to FormScaffolder.
  * Depending on those parameters, the fields can be used in ajax-context,
  * contain {@link TabSet}s etc.
  *
  * @return FieldList
  */
 public function getFieldList()
 {
     $fields = new FieldList();
     // tabbed or untabbed
     if ($this->tabbed) {
         $fields->push(new TabSet("Root", $mainTab = new Tab("Main")));
         $mainTab->setTitle(_t('SiteTree.TABMAIN', "Main"));
     }
     // Add logical fields directly specified in db config
     foreach ($this->obj->config()->db as $fieldName => $fieldType) {
         // Skip restricted fields
         if ($this->restrictFields && !in_array($fieldName, $this->restrictFields)) {
             continue;
         }
         // @todo Pass localized title
         if ($this->fieldClasses && isset($this->fieldClasses[$fieldName])) {
             $fieldClass = $this->fieldClasses[$fieldName];
             $fieldObject = new $fieldClass($fieldName);
         } else {
             $fieldObject = $this->obj->dbObject($fieldName)->scaffoldFormField(null, $this->getParamsArray());
         }
         // Allow fields to opt-out of scaffolding
         if (!$fieldObject) {
             continue;
         }
         $fieldObject->setTitle($this->obj->fieldLabel($fieldName));
         if ($this->tabbed) {
             $fields->addFieldToTab("Root.Main", $fieldObject);
         } else {
             $fields->push($fieldObject);
         }
     }
     // add has_one relation fields
     if ($this->obj->hasOne()) {
         foreach ($this->obj->hasOne() as $relationship => $component) {
             if ($this->restrictFields && !in_array($relationship, $this->restrictFields)) {
                 continue;
             }
             $fieldName = $component === 'SilverStripe\\ORM\\DataObject' ? $relationship : "{$relationship}ID";
             if ($this->fieldClasses && isset($this->fieldClasses[$fieldName])) {
                 $fieldClass = $this->fieldClasses[$fieldName];
                 $hasOneField = new $fieldClass($fieldName);
             } else {
                 $hasOneField = $this->obj->dbObject($fieldName)->scaffoldFormField(null, $this->getParamsArray());
             }
             if (empty($hasOneField)) {
                 continue;
             }
             // Allow fields to opt out of scaffolding
             $hasOneField->setTitle($this->obj->fieldLabel($relationship));
             if ($this->tabbed) {
                 $fields->addFieldToTab("Root.Main", $hasOneField);
             } else {
                 $fields->push($hasOneField);
             }
         }
     }
     // only add relational fields if an ID is present
     if ($this->obj->ID) {
         // add has_many relation fields
         if ($this->obj->hasMany() && ($this->includeRelations === true || isset($this->includeRelations['has_many']))) {
             foreach ($this->obj->hasMany() as $relationship => $component) {
                 if ($this->tabbed) {
                     $fields->findOrMakeTab("Root.{$relationship}", $this->obj->fieldLabel($relationship));
                 }
                 $fieldClass = isset($this->fieldClasses[$relationship]) ? $this->fieldClasses[$relationship] : 'SilverStripe\\Forms\\GridField\\GridField';
                 /** @var GridField $grid */
                 $grid = Object::create($fieldClass, $relationship, $this->obj->fieldLabel($relationship), $this->obj->{$relationship}(), GridFieldConfig_RelationEditor::create());
                 if ($this->tabbed) {
                     $fields->addFieldToTab("Root.{$relationship}", $grid);
                 } else {
                     $fields->push($grid);
                 }
             }
         }
         if ($this->obj->manyMany() && ($this->includeRelations === true || isset($this->includeRelations['many_many']))) {
             foreach ($this->obj->manyMany() as $relationship => $component) {
                 if ($this->tabbed) {
                     $fields->findOrMakeTab("Root.{$relationship}", $this->obj->fieldLabel($relationship));
                 }
                 $fieldClass = isset($this->fieldClasses[$relationship]) ? $this->fieldClasses[$relationship] : 'SilverStripe\\Forms\\GridField\\GridField';
                 /** @var GridField $grid */
                 $grid = Object::create($fieldClass, $relationship, $this->obj->fieldLabel($relationship), $this->obj->{$relationship}(), GridFieldConfig_RelationEditor::create());
                 if ($this->tabbed) {
                     $fields->addFieldToTab("Root.{$relationship}", $grid);
                 } else {
                     $fields->push($grid);
                 }
             }
         }
     }
     return $fields;
 }