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<?php
/**
* A DataFormatter object handles transformation of data from SilverStripe model objects to a particular output
* format, and vice versa. This is most commonly used in developing RESTful APIs.
*
* @package framework
* @subpackage formatters
*/
abstract class DataFormatter extends Object {
/**
* Set priority from 0-100.
* If multiple formatters for the same extension exist,
* we select the one with highest priority.
*
* @var int
*/
public static $priority = 50;
/**
* Follow relations for the {@link DataObject} instances
* ($has_one, $has_many, $many_many).
* Set to "0" to disable relation output.
*
* @todo Support more than one nesting level
*
* @var int
*/
public $relationDepth = 1;
/**
* Allows overriding of the fields which are rendered for the
* processed dataobjects. By default, this includes all
* fields in {@link DataObject::inheritedDatabaseFields()}.
*
* @var array
*/
protected $customFields = null;
/**
* Allows addition of fields
* (e.g. custom getters on a DataObject)
*
* @var array
*/
protected $customAddFields = null;
/**
* Allows to limit or add relations.
* Only use in combination with {@link $relationDepth}.
* By default, all relations will be shown.
*
* @var array
*/
protected $customRelations = null;
/**
* Fields which should be expicitly excluded from the export.
* Comes in handy for field-level permissions.
* Will overrule both {@link $customAddFields} and {@link $customFields}
*
* @var array
*/
protected $removeFields = null;
/**
* Specifies the mimetype in which all strings
* returned from the convert*() methods should be used,
* e.g. "text/xml".
*
* @var string
*/
protected $outputContentType = null;
/**
* Used to set totalSize properties on the output
* of {@link convertDataObjectSet()}, shows the
* total number of records without the "limit" and "offset"
* GET parameters. Useful to implement pagination.
*
* @var int
*/
protected $totalSize;
/**
* Get a DataFormatter object suitable for handling the given file extension.
*
* @param string $extension
* @return DataFormatter
*/
public static function for_extension($extension) {
$classes = ClassInfo::subclassesFor("DataFormatter");
array_shift($classes);
$sortedClasses = array();
foreach($classes as $class) {
$sortedClasses[$class] = singleton($class)->stat('priority');
}
arsort($sortedClasses);
foreach($sortedClasses as $className => $priority) {
$formatter = new $className();
if(in_array($extension, $formatter->supportedExtensions())) {
return $formatter;
}
}
}
/**
* Get formatter for the first matching extension.
*
* @param array $extensions
* @return DataFormatter
*/
public static function for_extensions($extensions) {
foreach($extensions as $extension) {
if($formatter = self::for_extension($extension)) return $formatter;
}
return false;
}
/**
* Get a DataFormatter object suitable for handling the given mimetype.
*
* @param string $mimeType
* @return DataFormatter
*/
public static function for_mimetype($mimeType) {
$classes = ClassInfo::subclassesFor("DataFormatter");
array_shift($classes);
$sortedClasses = array();
foreach($classes as $class) {
$sortedClasses[$class] = singleton($class)->stat('priority');
}
arsort($sortedClasses);
foreach($sortedClasses as $className => $priority) {
$formatter = new $className();
if(in_array($mimeType, $formatter->supportedMimeTypes())) {
return $formatter;
}
}
}
/**
* Get formatter for the first matching mimetype.
* Useful for HTTP Accept headers which can contain
* multiple comma-separated mimetypes.
*
* @param array $mimetypes
* @return DataFormatter
*/
public static function for_mimetypes($mimetypes) {
foreach($mimetypes as $mimetype) {
if($formatter = self::for_mimetype($mimetype)) return $formatter;
}
return false;
}
/**
* @param array $fields
*/
public function setCustomFields($fields) {
$this->customFields = $fields;
}
/**
* @return array
*/
public function getCustomFields() {
return $this->customFields;
}
/**
* @param array $fields
*/
public function setCustomAddFields($fields) {
$this->customAddFields = $fields;
}
/**
* @param array $relations
*/
public function setCustomRelations($relations) {
$this->customRelations = $relations;
}
/**
* @return array
*/
public function getCustomRelations() {
return $this->customRelations;
}
/**
* @return array
*/
public function getCustomAddFields() {
return $this->customAddFields;
}
/**
* @param array $fields
*/
public function setRemoveFields($fields) {
$this->removeFields = $fields;
}
/**
* @return array
*/
public function getRemoveFields() {
return $this->removeFields;
}
public function getOutputContentType() {
return $this->outputContentType;
}
/**
* @param int $size
*/
public function setTotalSize($size) {
$this->totalSize = (int)$size;
}
/**
* @return int
*/
public function getTotalSize() {
return $this->totalSize;
}
/**
* Returns all fields on the object which should be shown
* in the output. Can be customised through {@link self::setCustomFields()}.
*
* @todo Allow for custom getters on the processed object (currently filtered through inheritedDatabaseFields)
* @todo Field level permission checks
*
* @param DataObject $obj
* @return array
*/
protected function getFieldsForObj($obj) {
$dbFields = array();
// if custom fields are specified, only select these
if(is_array($this->customFields)) {
foreach($this->customFields as $fieldName) {
// @todo Possible security risk by making methods accessible - implement field-level security
if($obj->hasField($fieldName) || $obj->hasMethod("get{$fieldName}")) {
$dbFields[$fieldName] = $fieldName;
}
}
} else {
// by default, all database fields are selected
$dbFields = $obj->inheritedDatabaseFields();
}
if(is_array($this->customAddFields)) {
foreach($this->customAddFields as $fieldName) {
// @todo Possible security risk by making methods accessible - implement field-level security
if($obj->hasField($fieldName) || $obj->hasMethod("get{$fieldName}")) {
$dbFields[$fieldName] = $fieldName;
}
}
}
// add default required fields
$dbFields = array_merge($dbFields, array('ID'=>'Int'));
if(is_array($this->removeFields)) {
$dbFields = array_diff_key($dbFields, array_combine($this->removeFields,$this->removeFields));
}
return $dbFields;
}
/**
* Return an array of the extensions that this data formatter supports
*/
abstract public function supportedExtensions();
abstract public function supportedMimeTypes();
/**
* Convert a single data object to this format. Return a string.
*/
abstract public function convertDataObject(DataObjectInterface $do);
/**
* Convert a data object set to this format. Return a string.
*/
abstract public function convertDataObjectSet(SS_List $set);
/**
* @param string $strData HTTP Payload as string
*/
public function convertStringToArray($strData) {
user_error('DataFormatter::convertStringToArray not implemented on subclass', E_USER_ERROR);
}
}
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