Checking for existence of URL parameters

Question

I'm busy rewriting some from my spaghetti code into OOP classes. I'm still learning OOP and very new to the concept. From help from this answer from @EliasVanOotegemto on a previous question I've asked I have written the following class which sets up conditionals according to 4 values passed to it by a user and checking these values against URL parameters whether they exist or not

Here is the class with its interface:

ConditionsRefInterface.php

namespace PG\Referrer\Single\Post;
interface ConditionsReferInterface
{
 /**
 * @param (string)$authorReferrer
 * @return $this
 */
 public function setAuthorReferrer($isAuthorReferrer);
 /**
 * @param (string)$dateReferrer
 * @return $this
 */
 public function setDateReferrer($isDateReferrer);
 /**
 * @param (string)$searchReferrer
 * @return $this
 */
 public function setSearchReferrer($isSearchReferrer);
 /**
 * @param (string)$taxReferrer
 * @return $this
 */
 public function setTaxReferrer($isTaxReferrer);
 /**
 * @return (bool)
 */
 public function isAuthorReferrer();
 /**
 * @return (bool)
 */
 public function isDateReferrer();
 /**
 * @return (bool)
 */
 public function isSearchReferrer();
 /**
 * @return (bool)
 */
 public function isTaxReferrer();
}

ConditionsRef.php

namespace PG\Referrer\Single\Post;
class ConditionsRefer implements ConditionsReferInterface {
 /**
 * @var $authorReferrer = null
 */
 protected $isAuthorReferrer = null;
 /**
 * @var $dateReferrer = null
 */
 protected $isDateReferrer = null;
 /**
 * @var $searchReferrer = null
 */
 protected $isSearchReferrer = null;
 /**
 * @var $taxReferrer = null
 */
 protected $isTaxReferrer = null;
 /**
 * @param array $values = null;
 *
 * Accepted parameters that can be passed to $values. 
 * @param (string) authorReferrer
 * @param (string) dateReferrer
 * @param (string) searchReferrer
 * @param (string) taxReferrer
 *
 */
 public function __construct(array $values = null)
 {
 if(isset($values['authorReferrer']))
 $this->setAuthorReferrer($values['authorReferrer']);
 if(isset($values['dateReferrer']))
 $this->setDateReferrer($values['dateReferrer']);
 if(isset($values['searchReferrer']))
 $this->setSearchReferrer($values['searchReferrer']);
 if(isset($values['taxReferrer']))
 $this->setTaxReferrer($values['taxReferrer']);
 }
 /**
 * @param (string)$authorReferrer
 * @return $this
 */
 public function setAuthorReferrer($isAuthorReferrer)
 {
 $isAuthorReferrer = filter_var($isAuthorReferrer, FILTER_SANITIZE_STRING);
 $isAuthorReferrer = isset($_GET[$isAuthorReferrer]);
 $this->isAuthorReferrer = $isAuthorReferrer;
 return $this;
 }
 /**
 * @param (string)$dateReferrer
 * @return $this
 */
 public function setDateReferrer($isDateReferrer)
 {
 $isDateReferrer = filter_var($isDateReferrer, FILTER_SANITIZE_STRING);
 $isDateReferrer = isset($_GET[$isDateReferrer]);
 $this->isDateReferrer = $isDateReferrer;
 return $this;
 }
 /**
 * @param (string)$searchReferrer
 * @return $this
 */
 public function setSearchReferrer($isSearchReferrer)
 {
 $isSearchReferrer = filter_var($isSearchReferrer, FILTER_SANITIZE_STRING);
 $isSearchReferrer = isset($_GET[$isSearchReferrer]);
 $this->isSearchReferrer = $isSearchReferrer;
 return $this;
 }
 /**
 * @param (string)$taxReferrer
 * @return $this
 */
 public function setTaxReferrer($isTaxReferrer)
 {
 $isTaxReferrer = filter_var($isTaxReferrer, FILTER_SANITIZE_STRING);
 $isTaxReferrer = isset($_GET[$isTaxReferrer]);
 $this->isTaxReferrer = $isTaxReferrer;
 return $this;
 }
 /**
 * @return (bool)
 */
 public function isAuthorReferrer()
 {
 return $this->isAuthorReferrer;
 }
 /**
 * @return (bool)
 */
 public function isDateReferrer()
 {
 return $this->isDateReferrer;
 }
 /**
 * @return (bool)
 */
 public function isSearchReferrer()
 {
 return $this->isSearchReferrer;
 }
 /**
 * @return (bool)
 */
 public function isTaxReferrer()
 {
 return $this->isTaxReferrer;
 }
}

This works.

I have written another class that will use the conditions set by the class above. This is how it works

• User sets the arguments in this new class (QueryArgumentsRef.php) which is passed to the ConditionsRef class through the constructo method public function __construct(ConditionsReferInterface $conditionalReferrer, array $values = null)

• The get* methods from the ConditionsRef class is then used to get the conditional values through $this->conditionalReferrer->isAuthorReferrer() for instance

• $referArgs returns values according to the user set arguments

Here is the interface and class:

QueryArgumentsRefInterface.php

namespace PG\Referrer\Single\Post;
interface QueryArgumentsReferInterface
{
 /**
 * @return (array) arguments
 */
 public function getReferrerArgs();
}

QueryArgumentsRef.php

namespace PG\Referrer\Single\Post;
class QueryArgumentsRefer implements QueryArgumentsReferInterface 
{
 /**
 * @var $conditionalReferrer = null
 */
 protected $conditionalReferrer = null;
 /**
 * @var $values = null
 */
 protected $values = null;
 /**
 * @var $referArgs = null
 */
 protected $referArgs = null;
 /**
 * @param $conditionalReferrer
 * @param array $values = null;
 *
 * Accepted parameters that can be passed to $values. 
 * @param (string) authorReferrer
 * @param (string) dateReferrer
 * @param (string) searchReferrer
 * @param (string) taxReferrer
 *
 */
 public function __construct(ConditionsReferInterface $conditionalReferrer, array $values = null)
 {
 $this->conditionalReferrer = $conditionalReferrer;
 $this->values = $values;
 if(isset($values['authorReferrer']))
 $this->conditionalReferrer->setAuthorReferrer($values['authorReferrer']);
 if(isset($values['dateReferrer']))
 $this->conditionalReferrer->setDateReferrer($values['dateReferrer']);
 if(isset($values['searchReferrer']))
 $this->conditionalReferrer->setSearchReferrer($values['searchReferrer']);
 if(isset($values['taxReferrer']))
 $this->conditionalReferrer->setTaxReferrer($values['taxReferrer']);
 $this->referrerArgs();
 }
 public function referrerArgs()
 {
 switch (true) {
 case ($this->conditionalReferrer->isAuthorReferrer() && isset($this->values['authorReferrer'])):
 /**
 * If the referrer came from an author archive page
 */ 
 $author = $this->values['authorReferrer'];
 $author = filter_var($author, FILTER_SANITIZE_STRING);
 $referArgs = ['author' => (int) $_GET[$author]];
 break;
 case ($this->conditionalReferrer->isDateReferrer() && isset($this->values['dateReferrer'])):
 /**
 * If the referrer came from a date archive page
 */ 
 $date = $this->values['dateReferrer'];
 //$referArgs = (STILL TO WORKOUT);
 break;
 case ($this->conditionalReferrer->isSearchReferrer() && isset($this->values['searchReferrer'])):
 /**
 * If the referrer came from an search page
 */ 
 $search = $this->values['searchReferrer'];
 $search = filter_var($search, FILTER_SANITIZE_STRING);
 $search_terms = $_GET[$search];
 $referArgs = ['s' => (string) $search_terms];
 break;
 case ($this->conditionalReferrer->isTaxReferrer() && isset($this->values['taxReferrer'])):
 /**
 * If the referrer came from a taxonomy archive page
 */
 $tax = $this->values['taxReferrer'];
 $tax = filter_var($tax, FILTER_SANITIZE_STRING);
 $terms = $_GET[$tax]; 
 $terms = explode( ' ', $terms );
 $taxonomy_objects = get_taxonomy( $terms[0] );
 $hierarchical = $taxonomy_objects->hierarchical;
 $referArgs = ['tax_query' => [
 [
 'taxonomy' => (string) $terms[0], 
 'terms' => (int) $terms[1], 
 'include_children' => false
 ]
 ]];
 break;
 default:
 $referArgs = null;
 }
 $this->referArgs = (array) $referArgs;
 return $this;
 }
 /**
 * @return (array) query arguments according to referrer
 */
 public function getReferrerArgs()
 {
 return $this->referArgs;
 }
}

I can now use it at follows:

$a = new QueryArgumentsRefer(new ConditionsRefer(), ['authorReferrer' => 'aq', 'taxReferrer' => 'tq']);
 var_dump($a->getReferrerArgs());

where var_dump($a->getReferrerArgs()); produces the following output if I'm on a page where the query variable tq is set in the URL and the user have set the taxReferrer arguments

array(1) {
 ["tax_query"]=>
 array(1) {
 [0]=>
 array(3) {
 ["taxonomy"]=>
 string(8) "category"
 ["terms"]=>
 string(1) "1"
 ["include_children"]=>
 bool(false)
 }
 }
}

This will later be used to set up a new instance of WP_Query in another class.

Is the above code correct, or is there flaws that needs to be addressed? I welcome any constructive feedback, whether good or bad.

Answer 1

GET and setters

One of the points of @EliasVanOotegemto was that your class expects the $_GET variable to be set, which is not ideal because it makes your class very static and hard to reuse. What if you at some point do not store this data in GET, but in POST? Or in a session? You cannot use your class in that case.

That is why @EliasVanOotegemto suggested to pass the value contained in GET instead of passing the index at which the value is stored in GET. But through your new design, GET is actually used in two classes instead of one, which couples your classes together, and makes both hard to reuse.

Your setters should actually look really simple:

public function setDateReferrer($isDateReferrer)
 $this->isDateReferrer = $isDateReferrer;
 return $this;
}

And then used eg like this:

conditionsRefer->setDateReferrer($_GET['dateReferer']);

Naming

• class names should ideally be the same as the file in which they are stored (possibly with the keyword class added. ConditionsRef.php isn't a very good name (What's a Ref?), ConditionsReferer.php, ConditionsReferer.class.php, conditionsReferer.class.php would all be better (just choose one naming theme, and then stick with it).
• be consistent: either it's referer or referrer.
• isVariableName usually implies a boolean value. Your isDateReferrer etc do not seem to be boolean values though.

Comments

• your auto-generated comments seem wrong (eg @param (string)$authorReferrer vs $isAuthorReferrer, or protected $isAuthorReferrer vs @var $authorReferrer).
• sometimes, auto-generated comments might be fine, but I would prefer some additional information. For example, what is a taxReferrer? What values are $values?
• class level comments would be great. What is a ConditionsRefer?

Misc

• I'm not sure why you use filter_var in your code. If you want to protect against XSS attacks, I would clean the data when echoing it to the enduser, not at any other point (otherwise it becomes a guessing game when echoing data: did I already clean it?).
• I don't like using switch(true) instead of if-else, it just looks really wrong.
• do you actually expect a different implementations of ConditionsReferInterface than ConditionsRefer? It's hard for me to imagine one. If there is only one possible implementation of an interface, the interface isn't really needed.

• Pieter Goosen: Thanks for your input. The naming and comments for some reason got haywire and mixed, great spot. Already fixed that :-). On the switch, it is really more personal choice. What goes for one does not go for another
• Pieter Goosen: I found a really useful post on the programmer SE site regarding how to use superglobals like $_GET in OOP. Based on your recommendation and on recommendation from the answers on my previous question not to use superglobals in the manner in which I did, I'm going to create a Request class to handle the superglobals and then pass that to my other classes where needed. This will make my classes more testable. Note, the accepted answer there needs a serious rewrite :-)

Answer 2

Thanks for all the help. I ended up rewriting everything into one class. My main reason for this is that breaking this up into 3 three classes, it makes 2 of the classes a real mess through interface injection and quite hard to unit test. I think that the bulkiness of the class makes it quite difficult to maintain as separate smaller classes as we are working with 4 variables

At the end of the day, this class still deals with one concern in the complete system to follow, that is, testing 4 given variables against the returned array from a super global and returning the result as array in the form of query arguments and query variables.

It is not as clean and true as I would want it to be, and I'm sure the new class can be improved, but that is something for the near future.

CHANGES

• Removed the hardcoded $_GET variable as suggested by the accepted answer and linked answer

• Corrected the naming conventions used

• Better commenting in doc blocks

• Used htmlspecialchars() to guard against XSS only when the values from the URL (super global) is returned as query arguments and new query variables that is set in the URL

• Changed the switch() to a normal if/else statements.

• Removed the methods from the constructor

Here is my new class and interface

RequestReferrerHandlerInterface.php

<?php
namespace PG\Single\Post\Navigation;
interface RequestReferrerHandlerInterface
{
 /**
 * Setter setSuperGlobalVar
 * @param $superGlobalVar
 * @return $this
 */
 public function setSuperGlobalVar($superGlobalVar);
 /**
 * Returns an array of super global variables
 * @return (array) $this->superGlobalVar
 */ 
 public function getSuperGlobalVar();
 /**
 * Setter setAuthorReferrer
 * @param $authorReferrer
 * @return $this
 */
 public function setAuthorReferrer($authorReferrer);
 /**
 * Returns the value of the $authorReferrer property
 * @return (array) $this->authorReferrer
 */ 
 public function getAuthorReferrer();
 /**
 * Setter setDateReferrer
 * @param $dateReferrer
 * @return $this
 */
 public function setDateReferrer($dateReferrer);
 /**
 * Returns the value of the $dateReferrer property
 * @return (array) $this->dateReferrer
 */ 
 public function getDateReferrer();
 /**
 * Setter setSearchReferrer
 * @param $searchReferrer
 * @return $this
 */
 public function setSearchReferrer($searchReferrer);
 /**
 * Returns the value of the $searchReferrer property
 * @return (array) $this->searchReferrer
 */ 
 public function getSearchReferrer();
 /**
 * Setter setTaxReferrer
 * @param $taxReferrer
 * @return $this
 */
 public function setTaxReferrer($taxReferrer);
 /**
 * Returns the value of the $taxReferrer property
 * @return (array) $this->taxReferrer
 */ 
 public function getTaxReferrer();
 /**
 * Test $authorReferrer against $superGlobalVar
 *
 * @return (bool) true on success or false on failure
 */
 public function isAuthorReferrer();
 /**
 * Test $authorReferrer against $superGlobalVar
 *
 * @return (bool) true on success or false on failure
 */
 public function isDateReferrer();
 /**
 * Test $authorReferrer against $superGlobalVar
 *
 * @return (bool) true on success or false on failure
 */
 public function isSearchReferrer();
 /**
 * Test $authorReferrer against $superGlobalVar
 *
 * @return (bool) true on success or false on failure
 */
 public function isTaxReferrer();
 /**
 * Conditional which check if the current post is a referred post
 *
 * @return (bool) true on success or false on failure
 */
 public function isReferredPost();
 /**
 * Sets the values retrieves from the super global to an array
 * Will be passed as query arguments in a new instance of WP_Query
 *
 * @return (array) $queryArgs
 */ 
 public function referrerQueryArguments();
 /**
 * Gets the values from the super global and sets them into a new array which will be used to create 
 * new links to the referred posts to display adjacent posts 
 *
 * @return (array)$queryVars
 */ 
 public function referrerPermalinkVariables(); 
}

RequestReferrerHandler.php

<?php
namespace PG\Single\Post\Navigation;
/**
 * Test set values against the super global given. Returns conditional properties
 * which is boolean values. true is returned on success and false on failure
 *
 * @param $superGlobalVar Super global to test the values against
 * @param (string) $authorReferrer 
 * @param (string) $dateReferrer 
 * @param (string) $searchReferrer 
 * @param (string) $taxReferrer 
*/ 
class RequestReferrerHandler implements RequestReferrerHandlerInterface
{
 /**
 * @var (array) $superGlobalVar
 */
 protected $superGlobalVar;
 /**
 * @var (string) $authorReferrer
 */
 protected $authorReferrer;
 /**
 * @var (string) $dateReferrer
 */
 protected $dateReferrer;
 /**
 * @var (string) $searchReferrer
 */
 protected $searchReferrer;
 /**
 * @var (string) $taxReferrer
 */
 protected $taxReferrer;
 /**
 * Public constructor method
 *
 * @param $superGlobalVar Super global to get data from
 * @param $authorReferrer Query variable from author referrer to test
 * @param $dateReferrer Query variable from date referrer to test
 * @param $searchReferrer Query variable from search referrer to test
 * @param $taxReferrer Query variable from taxonomy referrer to test
 */
 public function __construct($superGlobalVar = null, $authorReferrer= null, $dateReferrer = null, $searchReferrer = null, $taxReferrer = null )
 {
 $this->superGlobalVar = $superGlobalVar;
 $this->authorReferrer = $authorReferrer;
 $this->dateReferrer = $dateReferrer;
 $this->searchReferrer = $searchReferrer;
 $this->taxReferrer = $taxReferrer;
 }
 /**
 * Setter setSuperGlobalVar
 * @param $superGlobalVar
 * @return $this
 */
 public function setSuperGlobalVar($superGlobalVar)
 {
 $this->superGlobalVar = $superGlobalVar;
 return $this;
 } 
 /**
 * Returns an array of super global variables
 * @return (array) $this->superGlobalVar
 */ 
 public function getSuperGlobalVar()
 {
 return $this->superGlobalVar;
 }
 /**
 * Setter setAuthorReferrer
 * @param $authorReferrer
 * @return $this
 */
 public function setAuthorReferrer($authorReferrer)
 {
 $this->authorReferrer = $authorReferrer;
 return $this;
 } 
 /**
 * Returns the value of the $authorReferrer property
 * @return (array) $this->authorReferrer
 */ 
 public function getAuthorReferrer()
 {
 return $this->authorReferrer;
 }
 /**
 * Setter setDateReferrer
 * @param $dateReferrer
 * @return $this
 */
 public function setDateReferrer($dateReferrer)
 {
 $this->dateReferrer = $dateReferrer;
 return $this;
 } 
 /**
 * Returns the value of the $dateReferrer property
 * @return (array) $this->dateReferrer
 */ 
 public function getDateReferrer()
 {
 return $this->dateReferrer;
 }
 /**
 * Setter setSearchReferrer
 * @param $searchReferrer
 * @return $this
 */
 public function setSearchReferrer($searchReferrer)
 {
 $this->searchReferrer = $searchReferrer;
 return $this;
 } 
 /**
 * Returns the value of the $searchReferrer property
 * @return (array) $this->searchReferrer
 */ 
 public function getSearchReferrer()
 {
 return $this->searchReferrer;
 }
 /**
 * Setter setTaxReferrer
 * @param $taxReferrer
 * @return $this
 */
 public function setTaxReferrer($taxReferrer)
 {
 $this->taxReferrer = $taxReferrer;
 return $this;
 } 
 /**
 * Returns the value of the $taxReferrer property
 * @return (array) $this->taxReferrer
 */ 
 public function getTaxReferrer()
 {
 return $this->$taxReferrer;
 }
 /**
 * Test $authorReferrer against $superGlobalVar
 *
 * @return (bool) true on success or false on failure
 */
 public function isAuthorReferrer()
 {
 if ($this->authorReferrer && isset($this->superGlobalVar[$this->authorReferrer])) { 
 $isAuthorReferrer = true;
 } else {
 $isAuthorReferrer = false;
 }
 return $isAuthorReferrer;
 }
 /**
 * Test $authorReferrer against $superGlobalVar
 *
 * @return (bool) true on success or false on failure
 */
 public function isDateReferrer()
 {
 if ($this->dateReferrer && isset($this->superGlobalVar[$this->dateReferrer])) { 
 $isDateReferrer = true;
 } else {
 $isDateReferrer = false;
 }
 return $isDateReferrer;
 }
 /**
 * Test $authorReferrer against $superGlobalVar
 *
 * @return (bool) true on success or false on failure
 */
 public function isSearchReferrer()
 {
 if ($this->searchReferrer && isset($this->superGlobalVar[$this->searchReferrer])) { 
 $isSearchReferrer = true;
 } else {
 $isSearchReferrer = false;
 }
 return $isSearchReferrer;
 }
 /**
 * Test $authorReferrer against $superGlobalVar
 *
 * @return (bool) true on success or false on failure
 */
 public function isTaxReferrer()
 {
 if ($this->taxReferrer && isset($this->superGlobalVar[$this->taxReferrer])) { 
 $isTaxReferrer = true;
 } else {
 $isTaxReferrer = false;
 }
 return $isTaxReferrer;
 }
 /**
 * Conditional which check if the current post is a referred post
 *
 * @return (bool) true on success or false on failure
 */
 public function isReferredPost()
 {
 if ($this->isAuthorReferrer() || $this->isDateReferrer() || $this->isSearchReferrer() || $this->isTaxReferrer()) {
 $isReferredPost = true;
 } else {
 $isReferredPost = false;
 }
 return $isReferredPost;
 }
 /**
 * Sets the values retrieves from the super global to an array
 * Will be passed as query arguments in a new instance of WP_Query
 *
 * @return (array) $queryArgs
 */ 
 public function referrerQueryArguments()
 {
 if (!$this->isReferredPost())
 return null;
 if ($this->isAuthorReferrer()) {
 $queryArgs = ['author' => (int) htmlspecialchars($this->superGlobalVar[$this->authorReferrer])];
 } elseif ($this->isDateReferrer()) {
 $queryArgs = ''; //@TODO Date archives
 } elseif ($this->isSearchReferrer()) {
 $queryArgs = ['s' => (string) htmlspecialchars($this->superGlobalVar[$this->searchReferrer])];
 } elseif ($this->isTaxReferrer()) {
 $terms = explode(' ', $this->superGlobalVar[$this->taxReferrer]) ;
 $queryArgs = ['tax_query' => [
 [
 'taxonomy' => (string) htmlspecialchars($terms[0]), 
 'terms' => (int) htmlspecialchars($terms[1]), 
 'include_children' => false
 ]
 ]];
 }
 return (array) $queryArgs;
 }
 /**
 * Gets the values from the super global and sets them into a new array which will be used to create 
 * new links to the referred posts to display adjacent posts 
 *
 * @return (array)$queryVars
 */ 
 public function referrerPermalinkVariables() 
 {
 if (!$this->isReferredPost())
 return null;
 if ($this->isAuthorReferrer()) {
 $queryVars = [$this->authorReferrer => htmlspecialchars($this->superGlobalVar[$this->authorReferrer])];
 } elseif ($this->isDateReferrer()) {
 $queryVars = ''; //@TODO Date archives
 } elseif ($this->isSearchReferrer()) {
 $queryVars = [$this->searchReferrer => str_replace( ' ', '+', htmlspecialchars($this->superGlobalVar[$this->searchReferrer]))];
 } elseif ($this->isTaxReferrer()) {
 $queryVars = [$this->taxReferrer => str_replace( ' ', '+', htmlspecialchars($this->superGlobalVar[$this->taxReferrer]))];
 }
 return (array)$queryVars;
 }
}

The class can then be used on its own (I will use this in a system which will return posts from a new instance of WP_Query in Wordpress according to the referrers set) and can easily be isolation tested. The following code

$a = new RequestReferrerHandler($_GET, 'aq', 'dq', 'sq', 'tq');
?><pre><?php var_dump($a->referrerQueryArguments()); ?></pre><?php 
?><pre><?php var_dump($a->referrerPermalinkVariables()); ?></pre><?php 

renders

array(1) {
 ["author"]=>
 int(2)
}

and

array(1) {
 ["aq"]=>
 string(1) "2"
}

when I'm on a single post page which was referred from an author page

Hope someone will find this useful :-)