如何在SilverStripe中动态更改字段类型

您可以使用 替换字段 http://api.silverstripe.org/3.1/class-FieldList.html#_replaceField

function getCMSFields() {
  $fields = parent::getCMSFields();
  $fields->replaceField('MyField', DropdownField::create('MyField', 'My field'));
  return $fields;
}

可以在getCMSField中添加条件

function getCMSFields() {
    $fields = parent::getCMSFields();
    $source = SomeDataObject::get();
    $fields->removeByName('MyField');
    if($source->count() > 1) {
        $fields->addFieldToTab('MyTab', DropdownField::create('MyField', 'My field', $source->map()->toArray()));
    } else {
        $fields->addFieldToTab('MyTab', CheckboxField::create('MyField', 'My field', $source->first()->Name));
    }
    return $fields;
}

希望有帮助。