I struggle with this problem for a while - and the reason is probably trivial.
Background
I've created parser module for my Yii2 application so I can call it from other places (mobile app, etc.) to get data from various websites. There may be many parser classes, all implementing same interface.
Project structure
...
/modules
\_ parser
\_components
\_parsers
\_SampleParser.php
\_controllers
\_DefaultController.php
\_Parser.php
...
I've removed some code for better readability.
DefaultController.php:
namespace app\modules\parser\controllers;
use Yii;
use yii\web\Controller;
use app\modules\parser\components\parsers;
use app\modules\parser\components\parsers\SampleParser;
/**
* Default controller for the `parser` module
*/
class DefaultController extends Controller
{
private function loadParser($parserName){
return new SampleParser(); // if I leave this here, everything works okay
$className = $parserName.'Parser';
$object = new $className();
if ($object instanceof IParseProvider){
return $object;
}
}
...
public function actionIndex()
{
$url = "http://google.com";
$parser = 'Sample';
$loadedParser = $this->loadParser($parser);
$response = $loadedParser->parse($url);
\Yii::$app->response->format = 'json';
return $response->toJson();
}
...
SampleParser.php:
<?php
namespace app\modules\parser\components\parsers;
use app\modules\parser\models\IParseProvider;
class SampleParser implements IParseProvider {
public function canParse($url){
}
public function parse($url){
}
}
Right now everything works more or less ok, so I guess I'm importing correct namespaces. But when I remove return new SampleParser(); and let the object to be created by string name, it fails with error:
PHP Fatal Error – yii\base\ErrorException
Class 'SampleParser' not found
with highlighted line:
$object = new $className();
What am I doing wrong here? Thanks!
Try again with help of Yii:
private function loadParser($parserName)
{
return \yii\di\Instance::ensure(
'app\modules\parser\components\parsers\\' . $parserName . 'Parser',
IParseProvider::class
);
}
Remember that ensure() throws \yii\base\InvalidConfigException when passed reference is not of the type you expect so you need to catch it at some point.
If you are using PHP < 5.5 instead of IParseProvider::class you can use full class name with it's namespace.
P.S. remove use app\modules\parser\components\parsers; unless you have got class named parsers you want to use.
Related
I am trying to inject one class (a simple PHP class) into another (an ORM\Entity annotated class), and getting an error, but I cannot discover the source. Looking at the code I feel like I am doing everything correctly, yet I cannot solve this error.
Here is the relevant code:
First, the class ORM\Entity where I want to inject the ErrorConstants class:
use Base\Model\Constants\ErrorConstants;
/**
* #ORM\Entity ...
*/
class CwPackagePeriod extends AbstractRestEntity
public $errors;
public function __construct()
{
parent::__construct();
$this->errors = new ErrorConstants();
}
}
The ErrorConstants class is a simple class that contains a list of error constants:
class ErrorConstants
{
public const ERR_MISSING = 'Record could not be found.';
}
The error occurs when I try to throw an exception in the CwPackagePeriod class if an integer value is out of bounds on a setter:
throw new InvalidOrMissingParameterException(
sprintf($this->errors::ERR_MISSING)
);
The error is the following:
Class name must be a valid object or a string
The AbstractRestEntity class does not contain any reference to ErrorConstants, and when I add the reference there, nothing changes with respect to the error. What am I doing wrong?
As u_mulder noted constants refer to class, not to class instance. In order to properly get the constants from your class you could use something like that in your ErrorConstants class:
public function getConstants()
{
$reflectionClass = new \ReflectionClass($this);
return $reflectionClass->getConstants();
}
then in your CwPackagePeriod class:
public function __construct()
{
parent::__construct();
$errorConstants = new ErrorConstants();
$this->errors = $errorConstants->getConstants();
}
...
throw new InvalidOrMissingParameterException(
sprintf($this->errors['ERR_MISSING']);
);
Of course the simplest solution would be to use just:
throw new InvalidOrMissingParameterException(
sprintf(ErrorConstants::ERR_MISSING);
);
Finally I would like to note, although it is not very intuitive, you CAN indeed use $this->errors::ERR_MISSING to get a constant. The reason because you get this error is probably because $this->errors is not defined in that part of code for some reason.
As the title states; how can I use the HTMLPurifier library inside my class?
I'm trying to get to grips with OOP and PHP classes for the first time and have successfully built a class that connects to my database using my database class and returns a blog article.
I would now like to parse the HTML markup for the blog article using HTMLPurifier but I would like to achieve this inside my blog class and I'm wondering how it can be achieved, as HTMLPurifier is a class.
My class so far:
namespace Blog\Reader;
use PDO;
use HTMLPurifier_Config; <--- trying to include it here
use \Database\Connect;
class BlogReader {
private static $instance = null;
private static $article = null;
private static $config = null;
private static $db = null;
private static function InitDB() {
if (self::$db) return;
try {
$connect = Connect::getInstance(self::$config['database']);
self::$db = $connect->getConnection();
} catch (Throwable $t) {}
}
private function __construct($config) {
self::$config = $config;
}
public static function getInstance($config) {
if (!self::$instance) {
self::$instance = new BlogReader($config);
}
return self::$instance;
}
public static function getArticle($id) {
self::InitDB();
try {
if (self::$db) {
$q = self::$db->prepare("
// sql
");
$q->bindValue(':id', (int) $id, PDO::PARAM_INT);
$q->execute();
self::$article = $q->fetchAll(PDO::FETCH_ASSOC);
//////////// <----- and trying to use it here
$HTMLPurifier_Config = HTMLPurifier_Config::createDefault();
$purifier = new HTMLPurifier($HTMLPurifier_Config);
///////////
} else {
throw new Exception("No database connection found.");
self::$article = null;
}
} catch (Throwable $t) {
self::$article = null;
}
return self::$article;
}
private function __clone() {}
private function __sleep() {}
private function __wakeup() {}
}
However, I get the following error log when trying anything like this:
Uncaught Error: Class 'HTMLPurifier_Config' not found in
....../php/classes/blog/reader/blogreader.class.php
And the line number of the error is on this line:
$HTMLPurifier_Config = HTMLPurifier_Config::createDefault();
My class directory structure:
[root]
[blog]
blog.php <--- using classes here
[php]
afs-autoload.php
[classes]
[blog]
[database]
[vendor]
[htmlpurifier-4.10.0]
[library]
HTMLPurifier.auto.php <--- this is what I used to `include` on blog.php to autoload HTMLPurifier_Config::createDefault() and new HTMLPurifier($purifier_config).
My Autoloader (afs-autoload.php) file:
define('CLASS_ROOT', dirname(__FILE__));
spl_autoload_register(function ($class) {
$file = CLASS_ROOT . '/classes/' . str_replace('\\', '/', strtolower($class)) . '.class.php';
if (file_exists($file)) {
require $file;
}
});
I literally started learning classes today, so I'm really baffled as to how I can achieve this, especially with the namespace system I used.
I hope somebody with better experience can guide me in the right direction.
Rewritten answer:
1) Your auto loader is looking for <class>.class.php files; but your HTMLPurifier_Config is in a HTMLPurifier.auto.php file.
2) Still in your autoloader: str_replace('\\' You do not need to escape characters when in single quotes, so this should be: str_replace('\'.
3) This excellent answer should help you learn when and how to use the use PHP keyword.
4) Your issue is not the scope of your use (I don't think you even need to use use). But is that your autoloader is looking for the wrong type of files. Try manually loading the class using require and seeing if it works properly.
Original Answer
namespace Blog\Reader;
use PDO;
use HTMLPurifier_Config;
What you're actually doing here is using the values within the defined namespace; so you're using:
Blog\Reader\HTMLPurifier_Config
If you're HTMLPurifier_Config file is within its own namespace you need to specify that so that the "use" grabs the right data!
If its not in its own namespace then it will be in the global namespace which is identified with a slash:
namespace Blog\Reader;
use PDO;
use \HTMLPurifier_Config;
If it is in the namespace HTMLPurifier, for example:
namespace Blog\Reader;
use PDO;
use \HTMLPurifier\HTMLPurifier_Config;
to load the correct data reference.
Just to wrap this up, if you are using namespaces inside a class which as been placed in a namespace, this is how you create your purifier objects:
$config = \HTMLPurifier_Config::createDefault();
$purifier = new \HTMLPurifier($config);
$clean_html = $purifier->purify($dirty_html);
You do not have to use a use command since the HTMLPurifier classes themselves are not in a namespace. But when your code is in a namespace, you need to pre-pend '\' to non-namespaced classes.
namespace \Tdiscus; // This is the line that makes the difference.
use \Tsugi\Util\Net;
class Threads {
...
$config = \HTMLPurifier_Config::createDefault();
...
$retval = new \stdClass();
...
$dbh = new \PDO($dsn, $user, $password);
}
Because you placed the class in a namespace, any "non-namespaced" classes need a "" prefix - like PDO and stdClass in the above example.
The HTMLPurifier folks could have put their classes in a namespace - but they chose not to do that.
Using namespaces is a common practice when developing libraries intended for use with composer. But HTMLPurifier existed before composer was in common use and their classes have a nice unique prefix because they started out in a global class namespace - so they decided to leave well enough alone and not break the non-dynamic loading / non-namespace legacy adopters of their library.
I need to use method from Nette library, that I'm including by use command. But it doesn't work as I want to, throws fatal error, that I am calling undefined method.
How should I approach that method to make it work? Stupid question, but I am kinda new to OOP...
Method from class PresenterComponent.php
public function getPresenter($need = TRUE)
{
return $this->lookup('Nette\Application\UI\Presenter', $need);
}
And my code, where I need to use that method:
use Nette\Application\UI\PresenterComponent;
class DatabaseCollectionAdapter extends ArrayDataAdapter
{
// ..... some code......
$this->user = $this->getPresenter()->getUser();
Error:
Fatal Error
Call to undefined method Ctech\Gridator\DataAdapter\DatabaseCollectionAdapter::getPresenter()
change this
$this->user = $this->getPresenter()->getUser();
to this:
$object = new yourObject(); // yourObject extends PresenterComponent
$this->user = $object->getPresenter()->getUser();
use Nette\Application\UI\PresenterComponent; does not include or do any kind of magic to make it's functions available on the fly.
https://secure.php.net/manual/de/language.namespaces.importing.php
It's just a shorthand that helps you to use PresenterComponent directly without specifying the whole namespace.
Your DatabaseCollectionAdapter or ArrayDataAdapter has to have a function that looks like this:
class AdapterClass
public function getPresenter() {
return new Nette\Application\UI\PresenterComponent;
}
}
or something like this
use Nette\Application\UI\PresenterComponent;
class AdapterClass
public function getPresenter() {
return new PresenterComponent;
}
}
I've got an Object Oriented library I wanted to add a method to, and while I'm fairly certain I could just go into the source of that library and add it, I imagine this is what's generally known as A Bad Idea.
How would I go about adding my own method to a PHP object correctly?
UPDATE ** editing **
The library I'm trying to add a method to is simpleHTML, nothing fancy, just a method to improve readability. So I tried adding to my code:
class simpleHTMLDOM extends simple_html_dom {
public function remove_node() {
$this->outertext = "";
}
}
which got me: Fatal error: Call to undefined method simple_html_dom_node::remove_node(). So obviously, when you grab an element in simpleHTML it returns an object of type simple_html_dom_node.
If I add the method to simple_html_dom_node my subclass isn't what will be created by simplHTML ... so stuck as to where to go next.
A solution would be to create a new class, that extends the one from your library -- and, then, use your class, which have have all methods of the original one, plus yours.
Here's a (very quick and simple) example :
class YourClass extends TheLibraryClass {
public function yourNewMethod() {
// do what you want here
}
}
And, then, you use your class :
$obj = new YourClass();
$obj->yourNewMethod();
And you can call the methods of the TheLibraryClass class, as yours inherits the properties and methods of that one :
$obj->aMethodFromTheLibrary();
About that, you can take a look at the Object Inheritance section of the manual.
And, as you guessed, modifying a library is definitly a bad idea : you'll have to re-do that modification each time you update the library !
(One day or another, you'll forget -- or one of your colleagues will forget ^^ )
You could do it with inheritance, but you could also use a decorator pattern if you do not need access to any protected members from SimpleHtml. This is a somewhat more flexible approach. See the linked page for details.
class MySimpleHtmlExtension
{
protected $_dom;
public function __construct(simple_html_dom $simpleHtml)
{
$this->_dom = $simpleHtml;
}
public function removeNode(simple_html_dom_node $node)
{
$node->outertext = '';
return $this;
}
public function __call($method, $args)
{
if(method_exists($this->_dom, $method)) {
return call_user_func_array(array($this->_dom , $method), $args));
}
throw new BadMethodCallException("$method does not exist");
}
}
You'd use the above like this
$ext = new MySimpleHtmlExtension( new simple_html_dom );
$ext->load('<html><body>Hello <span>World</span>!</body></html>');
$ext->removeNode( $ext->find('span', 0) );
I don't why adding the method would be bad, however if you want to so without editing the library, your best bet would be to extend the class like so:
class NewClass extends OldClass {
function newMethod() {
//do stuff
}
}
class myExtenstionClass extends SomeClassInLibrary
{
public function myMethod()
{
// your function definition
}
}
As Pascal suggests... read the manual :-)
I may just need a terminology update, but I have been playing in Magento and Joomla, and they do references like
$mage = new Mage;
$mage->block('blockname');
where class Mage through some process I am failing to figure out is calling:
class blockname extends something{
}
Don't quote me on that code, however I am looking to do something like that where I have a file that I can do $myscript->block('blockname'); and it will load and call the file with class blockname.
class Mage {
private $block;
public function block($blockname) {
if (!class_exists($blockname, true)) {
throw new InvalidArgumentException("Not a valid class name: $blockname");
}
$this->block = new $blockname;
}
}
The loading of the class definition (if not already done) is typically accomplished through autoloading (see here).