lib/components/web/form/fields/Relation.php
public function getRelationModelField()
    {
        $field = $this->model->tabularPrefix;
        if ($this->modelField->relationship->companionRole($this->modelField->modelRole) === 'child') {
            $field .= 'child_object_id';
        } else {
            $field .= 'parent_object_id';
        }

        return $field;
    }
public function getRelationModelField()
    {
        $field = $this->model->tabularPrefix;
        if ($this->modelField->relationship->companionRole($this->modelField->modelRole) === 'child') {
            $field .= 'child_object_id';
        } else {
            $field .= 'parent_object_id';
        }

        return $field;
    }
Get relation model field.

@return [[@doctodo return_type:getRelationModelField]] [[@doctodo return_description:getRelationModelField]]