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<?php
// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Generic exporter to take a stdClass and prepare it for return by webservice.
*
* @package core
* @copyright 2015 Damyon Wiese
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core\external;
defined('MOODLE_INTERNAL') || die();
require_once($CFG->libdir . '/externallib.php');
use stdClass;
use renderer_base;
use context;
use context_system;
use coding_exception;
use external_single_structure;
use external_multiple_structure;
use external_value;
use external_format_value;
/**
* Generic exporter to take a stdClass and prepare it for return by webservice, or as the context for a template.
*
* templatable classes implementing export_for_template, should always use a standard exporter if it exists.
* External functions should always use a standard exporter if it exists.
*
* @copyright 2015 Damyon Wiese
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class exporter {
/** @var array $related List of related objects used to avoid DB queries. */
protected $related = array();
/** @var stdClass|array The data of this exporter. */
protected $data = null;
/**
* Constructor - saves the persistent object, and the related objects.
*
* @param mixed $data - Either an stdClass or an array of values.
* @param array $related - An optional list of pre-loaded objects related to this object.
*/
public function __construct($data, $related = array()) {
$this->data = $data;
// Cache the valid related objects.
foreach (static::define_related() as $key => $classname) {
$isarray = false;
$nullallowed = false;
// Allow ? to mean null is allowed.
if (substr($classname, -1) === '?') {
$classname = substr($classname, 0, -1);
$nullallowed = true;
}
// Allow [] to mean an array of values.
if (substr($classname, -2) === '[]') {
$classname = substr($classname, 0, -2);
$isarray = true;
}
$missingdataerr = 'Exporter class is missing required related data: (' . get_called_class() . ') ';
$scalartypes = ['string', 'int', 'bool', 'float'];
$scalarcheck = 'is_' . $classname;
if ($nullallowed && (!array_key_exists($key, $related) || $related[$key] === null)) {
$this->related[$key] = null;
} else if ($isarray) {
if (array_key_exists($key, $related) && is_array($related[$key])) {
foreach ($related[$key] as $index => $value) {
if (!$value instanceof $classname && !$scalarcheck($value)) {
throw new coding_exception($missingdataerr . $key . ' => ' . $classname . '[]');
}
}
$this->related[$key] = $related[$key];
} else {
throw new coding_exception($missingdataerr . $key . ' => ' . $classname . '[]');
}
} else {
if (array_key_exists($key, $related) &&
((in_array($classname, $scalartypes) && $scalarcheck($related[$key])) ||
($related[$key] instanceof $classname))) {
$this->related[$key] = $related[$key];
} else {
throw new coding_exception($missingdataerr . $key . ' => ' . $classname);
}
}
}
}
/**
* Function to export the renderer data in a format that is suitable for a
* mustache template. This means raw records are generated as in to_record,
* but all strings are correctly passed through external_format_text (or external_format_string).
*
* @param renderer_base $output Used to do a final render of any components that need to be rendered for export.
* @return stdClass
*/
final public function export(renderer_base $output) {
$data = new stdClass();
$properties = self::read_properties_definition();
$values = (array) $this->data;
$othervalues = $this->get_other_values($output);
if (array_intersect_key($values, $othervalues)) {
// Attempt to replace a standard property.
throw new coding_exception('Cannot override a standard property value.');
}
$values += $othervalues;
$record = (object) $values;
foreach ($properties as $property => $definition) {
if (isset($data->$property)) {
// This happens when we have already defined the format properties.
continue;
} else if (!property_exists($record, $property) && array_key_exists('default', $definition)) {
// We have a default value for this property.
$record->$property = $definition['default'];
} else if (!property_exists($record, $property) && !empty($definition['optional'])) {
// Fine, this property can be omitted.
continue;
} else if (!property_exists($record, $property)) {
// Whoops, we got something that wasn't defined.
throw new coding_exception('Unexpected property ' . $property);
}
$data->$property = $record->$property;
// If the field is PARAM_RAW and has a format field.
if ($propertyformat = self::get_format_field($properties, $property)) {
if (!property_exists($record, $propertyformat)) {
// Whoops, we got something that wasn't defined.
throw new coding_exception('Unexpected property ' . $propertyformat);
}
$formatparams = $this->get_format_parameters($property);
$format = $record->$propertyformat;
list($text, $format) = external_format_text($data->$property, $format, $formatparams['context'],
$formatparams['component'], $formatparams['filearea'], $formatparams['itemid'], $formatparams['options']);
$data->$property = $text;
$data->$propertyformat = $format;
} else if ($definition['type'] === PARAM_TEXT) {
$formatparams = $this->get_format_parameters($property);
if (!empty($definition['multiple'])) {
foreach ($data->$property as $key => $value) {
$data->{$property}[$key] = external_format_string($value, $formatparams['context'],
$formatparams['striplinks'], $formatparams['options']);
}
} else {
$data->$property = external_format_string($data->$property, $formatparams['context'],
$formatparams['striplinks'], $formatparams['options']);
}
}
}
return $data;
}
/**
* Get the format parameters.
*
* This method returns the parameters to use with the functions external_format_text(), and
* external_format_string(). To override the default parameters, you can define a protected method
* called 'get_format_parameters_for_<propertyName>'. For example, 'get_format_parameters_for_description',
* if your property is 'description'.
*
* Your method must return an array containing any of the following keys:
* - context: The context to use. Defaults to $this->related['context'] if defined, else throws an exception.
* - component: The component to use with external_format_text(). Defaults to null.
* - filearea: The filearea to use with external_format_text(). Defaults to null.
* - itemid: The itemid to use with external_format_text(). Defaults to null.
* - options: An array of options accepted by external_format_text() or external_format_string(). Defaults to [].
* - striplinks: Whether to strip the links with external_format_string(). Defaults to true.
*
* @param string $property The property to get the parameters for.
* @return array
*/
final protected function get_format_parameters($property) {
$parameters = [
'component' => null,
'filearea' => null,
'itemid' => null,
'options' => [],
'striplinks' => true,
];
$candidate = 'get_format_parameters_for_' . $property;
if (method_exists($this, $candidate)) {
$parameters = array_merge($parameters, $this->{$candidate}());
}
if (!isset($parameters['context'])) {
if (!isset($this->related['context']) || !($this->related['context'] instanceof context)) {
throw new coding_exception("Unknown context to use for formatting the property '$property' in the " .
"exporter '" . get_class($this) . "'. You either need to add 'context' to your related objects, " .
"or create the method '$candidate' and return the context from there.");
}
$parameters['context'] = $this->related['context'];
} else if (!($parameters['context'] instanceof context)) {
throw new coding_exception("The context given to format the property '$property' in the exporter '" .
get_class($this) . "' is invalid.");
}
return $parameters;
}
/**
* Get the additional values to inject while exporting.
*
* These are additional generated values that are not passed in through $data
* to the exporter. For a persistent exporter - these are generated values that
* do not exist in the persistent class. For your convenience the format_text or
* format_string functions do not need to be applied to PARAM_TEXT fields,
* it will be done automatically during export.
*
* These values are only used when returning data via {@link self::export()},
* they are not used when generating any of the different external structures.
*
* Note: These must be defined in {@link self::define_other_properties()}.
*
* @param renderer_base $output The renderer.
* @return array Keys are the property names, values are their values.
*/
protected function get_other_values(renderer_base $output) {
return array();
}
/**
* Get the read properties definition of this exporter. Read properties combines the
* default properties from the model (persistent or stdClass) with the properties defined
* by {@link self::define_other_properties()}.
*
* @return array Keys are the property names, and value their definition.
*/
final public static function read_properties_definition() {
$properties = static::properties_definition();
$customprops = static::define_other_properties();
$customprops = static::format_properties($customprops);
$properties += $customprops;
return $properties;
}
/**
* Recursively formats a given property definition with the default fields required.
*
* @param array $properties List of properties to format
* @return array Formatted array
*/
final public static function format_properties($properties) {
foreach ($properties as $property => $definition) {
// Ensures that null is set to its default.
if (!isset($definition['null'])) {
$properties[$property]['null'] = NULL_NOT_ALLOWED;
}
if (!isset($definition['description'])) {
$properties[$property]['description'] = $property;
}
// If an array is provided, it may be a nested array that is unformatted so rinse and repeat.
if (is_array($definition['type'])) {
$properties[$property]['type'] = static::format_properties($definition['type']);
}
}
return $properties;
}
/**
* Get the properties definition of this exporter used for create, and update structures.
* The read structures are returned by: {@link self::read_properties_definition()}.
*
* @return array Keys are the property names, and value their definition.
*/
final public static function properties_definition() {
$properties = static::define_properties();
foreach ($properties as $property => $definition) {
// Ensures that null is set to its default.
if (!isset($definition['null'])) {
$properties[$property]['null'] = NULL_NOT_ALLOWED;
}
if (!isset($definition['description'])) {
$properties[$property]['description'] = $property;
}
}
return $properties;
}
/**
* Return the list of additional properties used only for display.
*
* Additional properties are only ever used for the read structure, and during
* export of the persistent data.
*
* The format of the array returned by this method has to match the structure
* defined in {@link \core\persistent::define_properties()}. The display properties
* can however do some more fancy things. They can define 'multiple' => true to wrap
* values in an external_multiple_structure automatically - or they can define the
* type as a nested array of more properties in order to generate a nested
* external_single_structure.
*
* You can specify an array of values by including a 'multiple' => true array value. This
* will result in a nested external_multiple_structure.
* E.g.
*
* 'arrayofbools' => array(
* 'type' => PARAM_BOOL,
* 'multiple' => true
* ),
*
* You can return a nested array in the type field, which will result in a nested external_single_structure.
* E.g.
* 'competency' => array(
* 'type' => competency_exporter::read_properties_definition()
* ),
*
* Other properties can be specifically marked as optional, in which case they do not need
* to be included in the export in {@link self::get_other_values()}. This is useful when exporting
* a substructure which cannot be set as null due to webservices protocol constraints.
* E.g.
* 'competency' => array(
* 'type' => competency_exporter::read_properties_definition(),
* 'optional' => true
* ),
*
* @return array
*/
protected static function define_other_properties() {
return array();
}
/**
* Return the list of properties.
*
* The format of the array returned by this method has to match the structure
* defined in {@link \core\persistent::define_properties()}. Howewer you can
* add a new attribute "description" to describe the parameter for documenting the API.
*
* Note that the type PARAM_TEXT should ONLY be used for strings which need to
* go through filters (multilang, etc...) and do not have a FORMAT_* associated
* to them. Typically strings passed through to format_string().
*
* Other filtered strings which use a FORMAT_* constant (hear used with format_text)
* must be defined as PARAM_RAW.
*
* @return array
*/
protected static function define_properties() {
return array();
}
/**
* Returns a list of objects that are related to this persistent.
*
* Only objects listed here can be cached in this object.
*
* The class name can be suffixed:
* - with [] to indicate an array of values.
* - with ? to indicate that 'null' is allowed.
*
* @return array of 'propertyname' => array('type' => classname, 'required' => true)
*/
protected static function define_related() {
return array();
}
/**
* Get the context structure.
*
* @return external_single_structure
*/
final protected static function get_context_structure() {
return array(
'contextid' => new external_value(PARAM_INT, 'The context id', VALUE_OPTIONAL),
'contextlevel' => new external_value(PARAM_ALPHA, 'The context level', VALUE_OPTIONAL),
'instanceid' => new external_value(PARAM_INT, 'The Instance id', VALUE_OPTIONAL),
);
}
/**
* Get the format field name.
*
* @param array $definitions List of properties definitions.
* @param string $property The name of the property that may have a format field.
* @return bool|string False, or the name of the format property.
*/
final protected static function get_format_field($definitions, $property) {
$formatproperty = $property . 'format';
if (($definitions[$property]['type'] == PARAM_RAW || $definitions[$property]['type'] == PARAM_CLEANHTML)
&& isset($definitions[$formatproperty])
&& $definitions[$formatproperty]['type'] == PARAM_INT) {
return $formatproperty;
}
return false;
}
/**
* Get the format structure.
*
* @param string $property The name of the property on which the format applies.
* @param array $definition The definition of the format property.
* @param int $required Constant VALUE_*.
* @return external_format_value
*/
final protected static function get_format_structure($property, $definition, $required = VALUE_REQUIRED) {
if (array_key_exists('default', $definition)) {
$required = VALUE_DEFAULT;
}
return new external_format_value($property, $required);
}
/**
* Returns the create structure.
*
* @return external_single_structure
*/
final public static function get_create_structure() {
$properties = self::properties_definition();
$returns = array();
foreach ($properties as $property => $definition) {
if ($property == 'id') {
// The can not be set on create.
continue;
} else if (isset($returns[$property]) && substr($property, -6) === 'format') {
// We've already treated the format.
continue;
}
$required = VALUE_REQUIRED;
$default = null;
// We cannot use isset here because we want to detect nulls.
if (array_key_exists('default', $definition)) {
$required = VALUE_DEFAULT;
$default = $definition['default'];
}
// Magically treat the contextid fields.
if ($property == 'contextid') {
if (isset($properties['context'])) {
throw new coding_exception('There cannot be a context and a contextid column');
}
$returns += self::get_context_structure();
} else {
$returns[$property] = new external_value($definition['type'], $definition['description'], $required, $default,
$definition['null']);
// Magically treat the format properties.
if ($formatproperty = self::get_format_field($properties, $property)) {
if (isset($returns[$formatproperty])) {
throw new coding_exception('The format for \'' . $property . '\' is already defined.');
}
$returns[$formatproperty] = self::get_format_structure($property,
$properties[$formatproperty], VALUE_REQUIRED);
}
}
}
return new external_single_structure($returns);
}
/**
* Returns the read structure.
*
* @return external_single_structure
*/
final public static function get_read_structure() {
$properties = self::read_properties_definition();
return self::get_read_structure_from_properties($properties);
}
/**
* Returns the read structure from a set of properties (recursive).
*
* @param array $properties The properties.
* @param int $required Whether is required.
* @param mixed $default The default value.
* @return external_single_structure
*/
final protected static function get_read_structure_from_properties($properties, $required = VALUE_REQUIRED, $default = null) {
$returns = array();
foreach ($properties as $property => $definition) {
if (isset($returns[$property]) && substr($property, -6) === 'format') {
// We've already treated the format.
continue;
}
$thisvalue = null;
$type = $definition['type'];
$proprequired = VALUE_REQUIRED;
$propdefault = null;
if (array_key_exists('default', $definition)) {
$propdefault = $definition['default'];
}
if (array_key_exists('optional', $definition)) {
// Mark as optional. Note that this should only apply to "reading" "other" properties.
$proprequired = VALUE_OPTIONAL;
}
if (is_array($type)) {
// This is a nested array of more properties.
$thisvalue = self::get_read_structure_from_properties($type, $proprequired, $propdefault);
} else {
if ($definition['type'] == PARAM_TEXT || $definition['type'] == PARAM_CLEANHTML) {
// PARAM_TEXT always becomes PARAM_RAW because filters may be applied.
$type = PARAM_RAW;
}
$thisvalue = new external_value($type, $definition['description'], $proprequired, $propdefault, $definition['null']);
}
if (!empty($definition['multiple'])) {
$returns[$property] = new external_multiple_structure($thisvalue, $definition['description'], $proprequired,
$propdefault);
} else {
$returns[$property] = $thisvalue;
// Magically treat the format properties (not possible for arrays).
if ($formatproperty = self::get_format_field($properties, $property)) {
if (isset($returns[$formatproperty])) {
throw new coding_exception('The format for \'' . $property . '\' is already defined.');
}
$returns[$formatproperty] = self::get_format_structure($property, $properties[$formatproperty]);
}
}
}
return new external_single_structure($returns, '', $required, $default);
}
/**
* Returns the update structure.
*
* This structure can never be included at the top level for an external function signature
* because it contains optional parameters.
*
* @return external_single_structure
*/
final public static function get_update_structure() {
$properties = self::properties_definition();
$returns = array();
foreach ($properties as $property => $definition) {
if (isset($returns[$property]) && substr($property, -6) === 'format') {
// We've already treated the format.
continue;
}
$default = null;
$required = VALUE_OPTIONAL;
if ($property == 'id') {
$required = VALUE_REQUIRED;
}
// Magically treat the contextid fields.
if ($property == 'contextid') {
if (isset($properties['context'])) {
throw new coding_exception('There cannot be a context and a contextid column');
}
$returns += self::get_context_structure();
} else {
$returns[$property] = new external_value($definition['type'], $definition['description'], $required, $default,
$definition['null']);
// Magically treat the format properties.
if ($formatproperty = self::get_format_field($properties, $property)) {
if (isset($returns[$formatproperty])) {
throw new coding_exception('The format for \'' . $property . '\' is already defined.');
}
$returns[$formatproperty] = self::get_format_structure($property,
$properties[$formatproperty], VALUE_OPTIONAL);
}
}
}
return new external_single_structure($returns);
}
}