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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/>.
/**
* Abstract class for objects saved to the DB.
*
* @package core
* @copyright 2015 Damyon Wiese
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
namespace core;
defined('MOODLE_INTERNAL') || die();
use coding_exception;
use invalid_parameter_exception;
use lang_string;
use ReflectionMethod;
use stdClass;
use renderer_base;
/**
* Abstract class for core objects saved to the DB.
*
* @copyright 2015 Damyon Wiese
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
*/
abstract class persistent {
/** The table name. */
const TABLE = null;
/** @var array The model data. */
private $data = array();
/** @var array The list of validation errors. */
private $errors = array();
/** @var boolean If the data was already validated. */
private $validated = false;
/**
* Create an instance of this class.
*
* @param int $id If set, this is the id of an existing record, used to load the data.
* @param stdClass $record If set will be passed to {@link self::from_record()}.
*/
public function __construct($id = 0, stdClass $record = null) {
global $CFG;
if ($id > 0) {
$this->raw_set('id', $id);
$this->read();
}
if (!empty($record)) {
$this->from_record($record);
}
if ($CFG->debugdeveloper) {
$this->verify_protected_methods();
}
}
/**
* This function is used to verify that custom getters and setters are declared as protected.
*
* Persistent properties should always be accessed via get('property') and set('property', 'value') which
* will call the custom getter or setter if it exists. We do not want to allow inconsistent access to the properties.
*/
final protected function verify_protected_methods() {
$properties = static::properties_definition();
foreach ($properties as $property => $definition) {
$method = 'get_' . $property;
if (method_exists($this, $method)) {
$reflection = new ReflectionMethod($this, $method);
if (!$reflection->isProtected()) {
throw new coding_exception('The method ' . get_class($this) . '::'. $method . ' should be protected.');
}
}
$method = 'set_' . $property;
if (method_exists($this, $method)) {
$reflection = new ReflectionMethod($this, $method);
if (!$reflection->isProtected()) {
throw new coding_exception('The method ' . get_class($this) . '::'. $method . ' should be protected.');
}
}
}
}
/**
* Data setter.
*
* This is the main setter for all the properties. Developers can implement their own setters (set_propertyname)
* and they will be called by this function. Custom setters should call internal_set() to finally set the value.
* Internally this is not used {@link self::to_record()} or
* {@link self::from_record()} because the data is not expected to be validated or changed when reading/writing
* raw records from the DB.
*
* @param string $property The property name.
* @return $this
*/
final public function set($property, $value) {
if (!static::has_property($property)) {
throw new coding_exception('Unexpected property \'' . s($property) .'\' requested.');
}
$methodname = 'set_' . $property;
if (method_exists($this, $methodname)) {
$this->$methodname($value);
return $this;
}
return $this->raw_set($property, $value);
}
/**
* Data getter.
*
* This is the main getter for all the properties. Developers can implement their own getters (get_propertyname)
* and they will be called by this function. Custom getters can use raw_get to get the raw value.
* Internally this is not used by {@link self::to_record()} or
* {@link self::from_record()} because the data is not expected to be validated or changed when reading/writing
* raw records from the DB.
*
* @param string $property The property name.
* @return mixed
*/
final public function get($property) {
if (!static::has_property($property)) {
throw new coding_exception('Unexpected property \'' . s($property) .'\' requested.');
}
$methodname = 'get_' . $property;
if (method_exists($this, $methodname)) {
return $this->$methodname();
}
return $this->raw_get($property);
}
/**
* Internal Data getter.
*
* This is the main getter for all the properties. Developers can implement their own getters
* but they should be calling {@link self::get()} in order to retrieve the value. Essentially
* the getters defined by the developers would only ever be used as helper methods and will not
* be called internally at this stage. In other words, do not expect {@link self::to_record()} or
* {@link self::from_record()} to use them.
*
* This is protected because it is only for raw low level access to the data fields.
* Note this function is named raw_get and not get_raw to avoid naming clashes with a property named raw.
*
* @param string $property The property name.
* @return mixed
*/
final protected function raw_get($property) {
if (!static::has_property($property)) {
throw new coding_exception('Unexpected property \'' . s($property) .'\' requested.');
}
if (!array_key_exists($property, $this->data) && !static::is_property_required($property)) {
$this->raw_set($property, static::get_property_default_value($property));
}
return isset($this->data[$property]) ? $this->data[$property] : null;
}
/**
* Data setter.
*
* This is the main setter for all the properties. Developers can implement their own setters
* but they should always be calling {@link self::set()} in order to set the value. Essentially
* the setters defined by the developers are helper methods and will not be called internally
* at this stage. In other words do not expect {@link self::to_record()} or
* {@link self::from_record()} to use them.
*
* This is protected because it is only for raw low level access to the data fields.
*
* @param string $property The property name.
* @param mixed $value The value.
* @return $this
*/
final protected function raw_set($property, $value) {
if (!static::has_property($property)) {
throw new coding_exception('Unexpected property \'' . s($property) .'\' requested.');
}
if (!array_key_exists($property, $this->data) || $this->data[$property] != $value) {
// If the value is changing, we invalidate the model.
$this->validated = false;
}
$this->data[$property] = $value;
return $this;
}
/**
* Return the custom definition of the properties of this model.
*
* Each property MUST be listed here.
*
* The result of this method is cached internally for the whole request.
*
* The 'default' value can be a Closure when its value may change during a single request.
* For example if the default value is based on a $CFG property, then it should be wrapped in a closure
* to avoid running into scenarios where the true value of $CFG is not reflected in the definition.
* Do not abuse closures as they obviously add some overhead.
*
* Examples:
*
* array(
* 'property_name' => array(
* 'default' => 'Default value', // When not set, the property is considered as required.
* 'message' => new lang_string(...), // Defaults to invalid data error message.
* 'null' => NULL_ALLOWED, // Defaults to NULL_NOT_ALLOWED. Takes NULL_NOW_ALLOWED or NULL_ALLOWED.
* 'type' => PARAM_TYPE, // Mandatory.
* 'choices' => array(1, 2, 3) // An array of accepted values.
* )
* )
*
* array(
* 'dynamic_property_name' => array(
* 'default' => function() {
* return $CFG->something;
* },
* 'type' => PARAM_INT,
* )
* )
*
* @return array Where keys are the property names.
*/
protected static function define_properties() {
return array();
}
/**
* Get the properties definition of this model..
*
* @return array
*/
final public static function properties_definition() {
global $CFG;
static $def = null;
if ($def !== null) {
return $def;
}
$def = static::define_properties();
$def['id'] = array(
'default' => 0,
'type' => PARAM_INT,
);
$def['timecreated'] = array(
'default' => 0,
'type' => PARAM_INT,
);
$def['timemodified'] = array(
'default' => 0,
'type' => PARAM_INT
);
$def['usermodified'] = array(
'default' => 0,
'type' => PARAM_INT
);
// List of reserved property names. Mostly because we have methods (getters/setters) which would confict with them.
// Think about backwards compability before adding new ones here!
$reserved = array('errors', 'formatted_properties', 'records', 'records_select', 'property_default_value',
'property_error_message', 'sql_fields');
foreach ($def as $property => $definition) {
// Ensures that the null property is always set.
if (!array_key_exists('null', $definition)) {
$def[$property]['null'] = NULL_NOT_ALLOWED;
}
// Warn the developers when they are doing something wrong.
if ($CFG->debugdeveloper) {
if (!array_key_exists('type', $definition)) {
throw new coding_exception('Missing type for: ' . $property);
} else if (isset($definition['message']) && !($definition['message'] instanceof lang_string)) {
throw new coding_exception('Invalid error message for: ' . $property);
} else if (in_array($property, $reserved)) {
throw new coding_exception('This property cannot be defined: ' . $property);
}
}
}
return $def;
}
/**
* Gets all the formatted properties.
*
* Formatted properties are properties which have a format associated with them.
*
* @return array Keys are property names, values are property format names.
*/
final public static function get_formatted_properties() {
$properties = static::properties_definition();
$formatted = array();
foreach ($properties as $property => $definition) {
$propertyformat = $property . 'format';
if (($definition['type'] == PARAM_RAW || $definition['type'] == PARAM_CLEANHTML)
&& array_key_exists($propertyformat, $properties)
&& $properties[$propertyformat]['type'] == PARAM_INT) {
$formatted[$property] = $propertyformat;
}
}
return $formatted;
}
/**
* Gets the default value for a property.
*
* This assumes that the property exists.
*
* @param string $property The property name.
* @return mixed
*/
final protected static function get_property_default_value($property) {
$properties = static::properties_definition();
if (!isset($properties[$property]['default'])) {
return null;
}
$value = $properties[$property]['default'];
if ($value instanceof \Closure) {
return $value();
}
return $value;
}
/**
* Gets the error message for a property.
*
* This assumes that the property exists.
*
* @param string $property The property name.
* @return lang_string
*/
final protected static function get_property_error_message($property) {
$properties = static::properties_definition();
if (!isset($properties[$property]['message'])) {
return new lang_string('invaliddata', 'error');
}
return $properties[$property]['message'];
}
/**
* Returns whether or not a property was defined.
*
* @param string $property The property name.
* @return boolean
*/
final public static function has_property($property) {
$properties = static::properties_definition();
return isset($properties[$property]);
}
/**
* Returns whether or not a property is required.
*
* By definition a property with a default value is not required.
*
* @param string $property The property name.
* @return boolean
*/
final public static function is_property_required($property) {
$properties = static::properties_definition();
return !array_key_exists('default', $properties[$property]);
}
/**
* Populate this class with data from a DB record.
*
* Note that this does not use any custom setter because the data here is intended to
* represent what is stored in the database.
*
* @param \stdClass $record A DB record.
* @return static
*/
final public function from_record(stdClass $record) {
$record = (array) $record;
foreach ($record as $property => $value) {
$this->raw_set($property, $value);
}
return $this;
}
/**
* Create a DB record from this class.
*
* Note that this does not use any custom getter because the data here is intended to
* represent what is stored in the database.
*
* @return \stdClass
*/
final public function to_record() {
$data = new stdClass();
$properties = static::properties_definition();
foreach ($properties as $property => $definition) {
$data->$property = $this->raw_get($property);
}
return $data;
}
/**
* Load the data from the DB.
*
* @return static
*/
final public function read() {
global $DB;
if ($this->get('id') <= 0) {
throw new coding_exception('id is required to load');
}
$record = $DB->get_record(static::TABLE, array('id' => $this->get('id')), '*', MUST_EXIST);
$this->from_record($record);
// Validate the data as it comes from the database.
$this->validated = true;
return $this;
}
/**
* Hook to execute before a create.
*
* Please note that at this stage the data has already been validated and therefore
* any new data being set will not be validated before it is sent to the database.
*
* This is only intended to be used by child classes, do not put any logic here!
*
* @return void
*/
protected function before_create() {
}
/**
* Insert a record in the DB.
*
* @return static
*/
final public function create() {
global $DB, $USER;
if ($this->raw_get('id')) {
// The validation methods rely on the ID to know if we're updating or not, the ID should be
// falsy whenever we are creating an object.
throw new coding_exception('Cannot create an object that has an ID defined.');
}
if (!$this->is_valid()) {
throw new invalid_persistent_exception($this->get_errors());
}
// Before create hook.
$this->before_create();
// We can safely set those values bypassing the validation because we know what we're doing.
$now = time();
$this->raw_set('timecreated', $now);
$this->raw_set('timemodified', $now);
$this->raw_set('usermodified', $USER->id);
$record = $this->to_record();
unset($record->id);
$id = $DB->insert_record(static::TABLE, $record);
$this->raw_set('id', $id);
// We ensure that this is flagged as validated.
$this->validated = true;
// After create hook.
$this->after_create();
return $this;
}
/**
* Hook to execute after a create.
*
* This is only intended to be used by child classes, do not put any logic here!
*
* @return void
*/
protected function after_create() {
}
/**
* Hook to execute before an update.
*
* Please note that at this stage the data has already been validated and therefore
* any new data being set will not be validated before it is sent to the database.
*
* This is only intended to be used by child classes, do not put any logic here!
*
* @return void
*/
protected function before_update() {
}
/**
* Update the existing record in the DB.
*
* @return bool True on success.
*/
final public function update() {
global $DB, $USER;
if ($this->raw_get('id') <= 0) {
throw new coding_exception('id is required to update');
} else if (!$this->is_valid()) {
throw new invalid_persistent_exception($this->get_errors());
}
// Before update hook.
$this->before_update();
// We can safely set those values after the validation because we know what we're doing.
$this->raw_set('timemodified', time());
$this->raw_set('usermodified', $USER->id);
$record = $this->to_record();
unset($record->timecreated);
$record = (array) $record;
// Save the record.
$result = $DB->update_record(static::TABLE, $record);
// We ensure that this is flagged as validated.
$this->validated = true;
// After update hook.
$this->after_update($result);
return $result;
}
/**
* Hook to execute after an update.
*
* This is only intended to be used by child classes, do not put any logic here!
*
* @param bool $result Whether or not the update was successful.
* @return void
*/
protected function after_update($result) {
}
/**
* Saves the record to the database.
*
* If this record has an ID, then {@link self::update()} is called, otherwise {@link self::create()} is called.
* Before and after hooks for create() or update() will be called appropriately.
*
* @return void
*/
final public function save() {
if ($this->raw_get('id') <= 0) {
$this->create();
} else {
$this->update();
}
}
/**
* Hook to execute before a delete.
*
* This is only intended to be used by child classes, do not put any logic here!
*
* @return void
*/
protected function before_delete() {
}
/**
* Delete an entry from the database.
*
* @return bool True on success.
*/
final public function delete() {
global $DB;
if ($this->raw_get('id') <= 0) {
throw new coding_exception('id is required to delete');
}
// Hook before delete.
$this->before_delete();
$result = $DB->delete_records(static::TABLE, array('id' => $this->raw_get('id')));
// Hook after delete.
$this->after_delete($result);
// Reset the ID to avoid any confusion, this also invalidates the model's data.
if ($result) {
$this->raw_set('id', 0);
}
return $result;
}
/**
* Hook to execute after a delete.
*
* This is only intended to be used by child classes, do not put any logic here!
*
* @param bool $result Whether or not the delete was successful.
* @return void
*/
protected function after_delete($result) {
}
/**
* Hook to execute before the validation.
*
* This hook will not affect the validation results in any way but is useful to
* internally set properties which will need to be validated.
*
* This is only intended to be used by child classes, do not put any logic here!
*
* @return void
*/
protected function before_validate() {
}
/**
* Validates the data.
*
* Developers can implement addition validation by defining a method as follows. Note that
* the method MUST return a lang_string() when there is an error, and true when the data is valid.
*
* protected function validate_propertyname($value) {
* if ($value !== 'My expected value') {
* return new lang_string('invaliddata', 'error');
* }
* return true
* }
*
* It is OK to use other properties in your custom validation methods when you need to, however note
* they might not have been validated yet, so try not to rely on them too much.
*
* Note that the validation methods should be protected. Validating just one field is not
* recommended because of the possible dependencies between one field and another,also the
* field ID can be used to check whether the object is being updated or created.
*
* When validating foreign keys the persistent should only check that the associated model
* exists. The validation methods should not be used to check for a change in that relationship.
* The API method setting the attributes on the model should be responsible for that.
* E.g. On a course model, the method validate_categoryid will check that the category exists.
* However, if a course can never be moved outside of its category it would be up to the calling
* code to ensure that the category ID will not be altered.
*
* @return array|true Returns true when the validation passed, or an array of properties with errors.
*/
final public function validate() {
global $CFG;
// Before validate hook.
$this->before_validate();
// If this object has not been validated yet.
if ($this->validated !== true) {
$errors = array();
$properties = static::properties_definition();
foreach ($properties as $property => $definition) {
// Get the data, bypassing the potential custom getter which could alter the data.
$value = $this->raw_get($property);
// Check if the property is required.
if ($value === null && static::is_property_required($property)) {
$errors[$property] = new lang_string('requiredelement', 'form');
continue;
}
// Check that type of value is respected.
try {
if ($definition['type'] === PARAM_BOOL && $value === false) {
// Validate_param() does not like false with PARAM_BOOL, better to convert it to int.
$value = 0;
}
if ($definition['type'] === PARAM_CLEANHTML) {
// We silently clean for this type. It may introduce changes even to valid data.
$value = clean_param($value, PARAM_CLEANHTML);
}
validate_param($value, $definition['type'], $definition['null']);
} catch (invalid_parameter_exception $e) {
$errors[$property] = static::get_property_error_message($property);
continue;
}
// Check that the value is part of a list of allowed values.
if (isset($definition['choices']) && !in_array($value, $definition['choices'])) {
$errors[$property] = static::get_property_error_message($property);
continue;
}
// Call custom validation method.
$method = 'validate_' . $property;
if (method_exists($this, $method)) {
// Warn the developers when they are doing something wrong.
if ($CFG->debugdeveloper) {
$reflection = new ReflectionMethod($this, $method);
if (!$reflection->isProtected()) {
throw new coding_exception('The method ' . get_class($this) . '::'. $method . ' should be protected.');
}
}
$valid = $this->{$method}($value);
if ($valid !== true) {
if (!($valid instanceof lang_string)) {
throw new coding_exception('Unexpected error message.');
}
$errors[$property] = $valid;
continue;
}
}
}
$this->validated = true;
$this->errors = $errors;
}
return empty($this->errors) ? true : $this->errors;
}
/**
* Returns whether or not the model is valid.
*
* @return boolean True when it is.
*/
final public function is_valid() {
return $this->validate() === true;
}
/**
* Returns the validation errors.
*
* @return array
*/
final public function get_errors() {
$this->validate();
return $this->errors;
}
/**
* Extract a record from a row of data.
*
* Most likely used in combination with {@link self::get_sql_fields()}. This method is
* simple enough to be used by non-persistent classes, keep that in mind when modifying it.
*
* e.g. persistent::extract_record($row, 'user'); should work.
*
* @param stdClass $row The row of data.
* @param string $prefix The prefix the data fields are prefixed with, defaults to the table name followed by underscore.
* @return stdClass The extracted data.
*/
public static function extract_record($row, $prefix = null) {
if ($prefix === null) {
$prefix = str_replace('_', '', static::TABLE) . '_';
}
$prefixlength = strlen($prefix);
$data = new stdClass();
foreach ($row as $property => $value) {
if (strpos($property, $prefix) === 0) {
$propertyname = substr($property, $prefixlength);
$data->$propertyname = $value;
}
}
return $data;
}
/**
* Load a list of records.
*
* @param array $filters Filters to apply.
* @param string $sort Field to sort by.
* @param string $order Sort order.
* @param int $skip Limitstart.
* @param int $limit Number of rows to return.
*
* @return static[]
*/
public static function get_records($filters = array(), $sort = '', $order = 'ASC', $skip = 0, $limit = 0) {
global $DB;
$orderby = '';
if (!empty($sort)) {
$orderby = $sort . ' ' . $order;
}
$records = $DB->get_records(static::TABLE, $filters, $orderby, '*', $skip, $limit);
$instances = array();
foreach ($records as $record) {
$newrecord = new static(0, $record);
array_push($instances, $newrecord);
}
return $instances;
}
/**
* Load a single record.
*
* @param array $filters Filters to apply.
* @return false|static
*/
public static function get_record($filters = array()) {
global $DB;
$record = $DB->get_record(static::TABLE, $filters);
return $record ? new static(0, $record) : false;
}
/**
* Load a list of records based on a select query.
*
* @param string $select
* @param array $params
* @param string $sort
* @param string $fields
* @param int $limitfrom
* @param int $limitnum
* @return static[]
*/
public static function get_records_select($select, $params = null, $sort = '', $fields = '*', $limitfrom = 0, $limitnum = 0) {
global $DB;
$records = $DB->get_records_select(static::TABLE, $select, $params, $sort, $fields, $limitfrom, $limitnum);
// We return class instances.
$instances = array();
foreach ($records as $key => $record) {
$instances[$key] = new static(0, $record);
}
return $instances;
}
/**
* Return the list of fields for use in a SELECT clause.
*
* Having the complete list of fields prefixed allows for multiple persistents to be fetched
* in a single query. Use {@link self::extract_record()} to extract the records from the query result.
*
* @param string $alias The alias used for the table.
* @param string $prefix The prefix to use for each field, defaults to the table name followed by underscore.
* @return string The SQL fragment.
*/
public static function get_sql_fields($alias, $prefix = null) {
global $CFG;
$fields = array();
if ($prefix === null) {
$prefix = str_replace('_', '', static::TABLE) . '_';
}
// Get the properties and move ID to the top.
$properties = static::properties_definition();
$id = $properties['id'];
unset($properties['id']);
$properties = array('id' => $id) + $properties;
foreach ($properties as $property => $definition) {
$as = $prefix . $property;
$fields[] = $alias . '.' . $property . ' AS ' . $as;
// Warn developers that the query will not always work.
if ($CFG->debugdeveloper && strlen($as) > 30) {
throw new coding_exception("The alias '$as' for column '$alias.$property' exceeds 30 characters" .
" and will therefore not work across all supported databases.");
}
}
return implode(', ', $fields);
}
/**
* Count a list of records.
*
* @param array $conditions An array of conditions.
* @return int
*/
public static function count_records(array $conditions = array()) {
global $DB;
$count = $DB->count_records(static::TABLE, $conditions);
return $count;
}
/**
* Count a list of records.
*
* @param string $select
* @param array $params
* @return int
*/
public static function count_records_select($select, $params = null) {
global $DB;
$count = $DB->count_records_select(static::TABLE, $select, $params);
return $count;
}
/**
* Check if a record exists by ID.
*
* @param int $id Record ID.
* @return bool
*/
public static function record_exists($id) {
global $DB;
return $DB->record_exists(static::TABLE, array('id' => $id));
}
/**
* Check if a records exists.
*
* @param string $select
* @param array $params
* @return bool
*/
public static function record_exists_select($select, array $params = null) {
global $DB;
return $DB->record_exists_select(static::TABLE, $select, $params);
}
}