PHP project without using conditional statements - php

Question

There is a page, on the page there are fields for filling, these fields are intended for entering data on a certain product. Three products with their characteristics are offered for filling.
The main feature of the project is that I am forbidden to use conditional statements (if, else, switch case, ternary) for handling differences in product types.
My question is: Is there a way to accomplish this project without using conditional statements ?
In my project used conditional statements. But I need to redo it without using conditional statements.
This is the method insertData() that accepts the data entered by the user:
public function insertData(){
$sku = filter_input(INPUT_POST, 'sku');
$name = filter_input(INPUT_POST, 'name');
$price = filter_input(INPUT_POST, 'price');
$size_mb = filter_input(INPUT_POST, 'size_mb');
$book_weight = filter_input(INPUT_POST, 'b_weight');
$height = filter_input(INPUT_POST, 'height');
$width = filter_input(INPUT_POST, 'width');
$length = filter_input(INPUT_POST, 'length');
$_SESSION["sku"] = $sku;
$_SESSION["name"] = $name;
$_SESSION["price"] = $price;
$product_Validation = new Product_Validation();
$product_Validation->productValidation($sku, $name, $price, $size_mb, $book_weight, $height, $width, $length);
// if(!isset($_SESSION['mb_error'])){
// $product_Validation->insertDvd($sku, $name, $price, $size_mb);
// } elseif(!isset($_SESSION['boo_error'])){
// $product_Validation->insertBook($sku, $name, $price, $book_weight);
// } elseif(!isset($_SESSION['w_error'])){
// $product_Validation->InsertFurniture($sku, $name, $price, $height, $width, $length);
// }
!isset($_SESSION['mb_error']) ? $product_Validation->insertDvd($sku, $name, $price, $size_mb)
: (!isset($_SESSION['boo_error'])
? $product_Validation->insertBook($sku, $name, $price, $book_weight)
: (!isset($_SESSION['w_error'])
? $product_Validation->InsertFurniture($sku, $name, $price, $height, $width, $length) : die ) );
}
This is the class where I validate the input and then add each product to their tables in the database:
// In this class, input data is validated. Created three methods that send verified data to the database.
// Above ternary expressions were created and commented out conditional statements, this was done to make it easier
// for the reader of the code to understand what the code is doing.
session_start();
class Product_Validation
{
public static function redirectToaddPage(){
header("Location: http://product-app/product_add");
}
public static function redirectToMainPage(){
header("Location: http://product-app/");
}
public function productValidation($sku, $name, $price, $size_mb, $book_weight, $height, $width, $length ){
// if(empty($sku)){
// $_SESSION['sku_error']='Please insert SKU.';
// }elseif(iconv_strlen($sku)<5){
// $_SESSION['sku_error']='sku must be at least 5 characters.';
// }
$skuVal = (empty($sku)) ? $_SESSION['sku_error']='Please insert SKU.'
: ((iconv_strlen($sku)<5) ? $_SESSION['sku_error']='sku must be at least 5 characters.' : Product_Validation :: redirectToaddPage());
// if(empty($name)){
// $_SESSION['name_error']='Please insert name.';
// }elseif(iconv_strlen($name)<3){
// $_SESSION['name_error']='name must be at least 3 characters.';
// }
$nameVal = (empty($name)) ? $_SESSION['name_error']='Please insert name.'
: ((iconv_strlen($name)<3) ? $_SESSION['name_error']='name must be at least 3 characters.' : Product_Validation :: redirectToaddPage());
// if(empty($price)){
// $_SESSION['price_error']='Please insert price.';
// }elseif(preg_match( "/[^0-9,.]/", $price)){
// $_SESSION['price_error']='Only integers and rational numbers are allowed.';
// }
$priceVal = (empty($price)) ? $_SESSION['price_error']='Please insert price.'
: ((preg_match( "/[^0-9,.]/", $price)) ? $_SESSION['price_error']='Only integers and rational numbers are allowed.' : Product_Validation :: redirectToaddPage());
// // DVD input validation
// if(empty($size_mb)){
// $_SESSION['mb_error']='*Please insert DVD size.';
// }elseif(preg_match( "/[^0-9]/", $size_mb)){
// $_SESSION['mb_error']='Only integer numbers are allowed.';
// }
$sizeVal = (empty($size_mb)) ? $_SESSION['mb_error']='Please insert DVD size.'
: ((preg_match( "/[^0-9,.]/", $size_mb)) ? $_SESSION['mb_error']='Only integer numbers are allowed.' : Product_Validation :: redirectToaddPage());
// // Book input validation
// if(empty($book_weight)){
// $_SESSION['boo_error']='*Please insert Book size.';
// }elseif(preg_match( "/[^0-9,.]/", $book_weight)){
// $_SESSION['boo_error']='Only integers and rational numbers are allowed.';
// }
$weightVal = (empty($book_weight)) ? $_SESSION['boo_error']='Please insert Book size.'
: ((preg_match( "/[^0-9,.]/", $book_weight)) ? $_SESSION['boo_error']='Only integers and rational numbers are allowed.' : Product_Validation :: redirectToaddPage());
// Furniture input validation
// if(empty($height) && empty($width) && empty($length)){
// $_SESSION['h_error']='*Please insert Furniture height.';
// $_SESSION['w_error']='*Please insert Furniture width.';
// $_SESSION['l_error']='*Please insert Furniture lenght.';
// }elseif(preg_match( "/[^0-9,.]/", $height)){
// $_SESSION['h_error']='Only integers and rational numbers are allowed.';
// }elseif(preg_match( "/[^0-9,.]/", $width)){
// $_SESSION['w_error']='Only integers and rational numbers are allowed.';
// }elseif(preg_match( "/[^0-9,.]/", $length)){
// $_SESSION['l_error']='Only integers and rational numbers are allowed.';
// }
$furVal1 = (empty($height)) ? $_SESSION['h_error']='*Please insert Furniture height.'
: ((preg_match( "/[^0-9,.]/", $height)) ? $_SESSION['h_error']='Only integers and rational numbers are allowed.': Product_Validation :: redirectToaddPage());
$furVal2 = (empty($width)) ? $_SESSION['w_error']='*Please insert Furniture width.'
: ((preg_match( "/[^0-9,.]/", $width)) ? $_SESSION['w_error']='Only integers and rational numbers are allowed.': Product_Validation :: redirectToaddPage());
$furVal3 = (empty($length)) ? $_SESSION['l_error']='*Please insert Furniture lenght.'
: ((preg_match( "/[^0-9,.]/", $length)) ? $_SESSION['w_error']='Only integers and rational numbers are allowed.': Product_Validation :: redirectToaddPage());
Product_Validation :: redirectToaddPage();
}
// If a session with certain names is not created, then the entered data is considered valid and is sent to the database
public function insertDvd($sku, $name, $price, $size_mb){
$dvdInsert = !isset($_SESSION['sku_error']) && !isset($_SESSION['name_error']) && !isset($_SESSION['price_error']) && !isset($_SESSION['mb_error'])
? $InsertDvd = new Product_Dvd() : die();
!isset($_SESSION['sku_error']) ? $InsertDvd->setSku($sku) : null;
!isset($_SESSION['name_error']) ? $InsertDvd->setName($name) : null;
!isset($_SESSION['price_error']) ? $InsertDvd->setPrice($price) : null;
!isset($_SESSION['mb_error']) ? $InsertDvd->setSize($size_mb) : null;
// $InsertDvd->insertProducts() ? header("Location: http://product-app/") : die();
$InsertDvd->insertProducts() ? Product_Validation :: redirectToMainPage() : die();
}
public function insertBook($sku, $name, $price, $book_weight){
$bookInsert = !isset($_SESSION['sku_error']) && !isset($_SESSION['name_error']) && !isset($_SESSION['price_error']) && !isset($_SESSION['boo_error'])
? $InsertBook = new Product_Book() : die();
!isset($_SESSION['sku_error']) ? $InsertBook->setSku($sku) : null;
!isset($_SESSION['name_error']) ? $InsertBook->setName($name) : null;
!isset($_SESSION['price_error']) ? $InsertBook->setPrice($price) : null;
!isset($_SESSION['boo_error']) ? $InsertBook->setWeight($book_weight) : null;
$InsertBook->insertProducts() ? Product_Validation :: redirectToMainPage() : die();
}
public function insertFurniture($sku, $name, $price, $height, $width, $length){
$bookInsert = !isset($_SESSION['sku_error']) && !isset($_SESSION['name_error']) && !isset($_SESSION['price_error']) && !isset($_SESSION['h_error'])
&& !isset($_SESSION['w_error']) && !isset($_SESSION['l_error'])
? $InsertFurniture = new Product_Furniture() : die();
!isset($_SESSION['sku_error']) ? $InsertFurniture->setSku($sku) : null;
!isset($_SESSION['name_error']) ? $InsertFurniture->setName($name) : null;
!isset($_SESSION['price_error']) ? $InsertFurniture->setPrice($price) : null;
!isset($_SESSION['h_error']) ? $InsertFurniture->setHeight($height) : null;
!isset($_SESSION['w_error']) ? $InsertFurniture->setWidth($width) : null;
!isset($_SESSION['l_error']) ? $InsertFurniture->setLength($length) : null;
$InsertFurniture->insertProducts() ? Product_Validation :: redirectToMainPage() : die();
}
}

Answer 1

First - Don't use the session just because it's there, pass your values around. The reasons for this are many but trust me for the time being.
Second - Start by making a map of the validators/inserters:
$validators = [
'dvd' => 'DVDValidator',
'book' => 'BookValidator',
'furniture' => 'FurnitureValidator',
'none' => 'NoneValidator'
]
Then, get the validator from the array
$type = filter_input(INPUT_POST, 'type');
Then get the class from the validators array, and make it do the validation
$validatorClass = $validators[$type];
$validator = new $validatorClass();
//Having a function with many parameters is bad, next time try to use an array
$validator->validate($sku, $name, $price, $size_mb, $book_weight, $height, $width, $length);
You shouldn't have different ways of inserting your products, but if you do, apply the same strategy that you used for the validators. If you are just storing a couple extra fields that are not common between the different products, you can have a json field called extra
For example, DVD has a directory, movie category, length, ratings, etc..
$extra = [
'length' => 120,
'director' => 'Steven Spielberg',
'ratings' => 5
]
json_encode($extra)

Answer 2

The normal approach to use while working with this kind of scenario would be to implement the Strategy Pattern.
The implementation will vary based on your context, your needs, and how you like to work with PHP, You can combine the Factory and the Strategy Pattern or rely on some sort of automatic dependency injection (like the example will do if on some other context).
While totally removing the use of conditionals may not be achievable in this scenario because of the nature of the request, by implementing the strategy pattern you can reduce the complexity of the code.
People Interested in this question should read more about Software Design Principles, Solid Principles, and Design Patterns.
Note: I have tried to answer this question based on its content and the comments by the original OP whose objective seemed to be to reduce the needs of the conditionals for Calling the actual validation and the Insert piece of the logic.
--
A quick demonstration of how you use the Strategy Pattern for solving this problem with plain PHP using pre-instantiated strategies
// Define your product types :)
enum ProductType: string
{
case DVD = 'dvd';
}
// In this class you Determine the strategy to be used to validate a product, by its product type and then run the rules.
class ProductValidationStrategyContext
{
public function __construct(protected iterable $productValidationStrategies) {}
public function validateProduct(string $productType, array $productData): bool
{
foreach ($this->productValidationStrategies as $productValidationStrategy) {
if ($productValidationStrategy->canValidateProduct($productType)) {
return $productValidationStrategy->validateProduct($productData);
}
}
throw new LogicException('Invalid Product type provided');
}
}
// Set up an interface for your strategies.
interface ProductValidationStrategyInterface
{
public function canValidateProduct(string $productType): bool;
public function validateProduct(array $productData): bool;
}
// This class will determine if a product type of dvd has valid data.
// Dvd Product Data is flag valid as long as it has a title with more of 3 letters
class DVDProductValidationStrategy implements ProductValidationStrategyInterface
{
public function canValidateProduct(string $productType): bool
{
return $productType === ProductType::DVD->value;
}
public function validateProduct(array $productData): bool
{
//... Validation Rules goes here, you will not be able to not use conditionals unless relying on a library
// or project that runs the conditionals for you
if (!isset($productData['title']) || strlen($productData['title']) < 3) {
return false;
}
return true;
}
}
// In This class we determine which is the strategy to be used to insert the product and then insert it.
class ProductInsertStrategyContext
{
public function __construct(protected iterable $productValidationStrategies) {}
public function insertProduct(string $productType, array $productData): bool
{
foreach ($this->productValidationStrategies as $productValidationStrategy) {
if ($productValidationStrategy->canInsertProduct($productType)) {
return $productValidationStrategy->insertProduct($productData);
}
}
throw new LogicException('Invalid Product type provided');
}
}
// Set up an interface for your strategies.
interface ProductInsertStrategyInterface
{
public function canInsertProduct(string $productType): bool;
public function insertProduct(array $productData): bool;
}
class DVDProductInsertStrategy implements ProductInsertStrategyInterface
{
public function canInsertProduct(string $productType): bool
{
return $productType === ProductType::DVD->value;
}
public function insertProduct(array $productData): bool
{
// Product Insert logic goes here...
return true;
}
}
$productType = 'dvd';
$productData = [
'title' => '123'
];
$availableProductValidationStrategies = [new DVDProductValidationStrategy()];
$availableProductInsertStrategies = [new DVDProductInsertStrategy()];
$productValidationStrategyContext = new ProductValidationStrategyContext($availableProductValidationStrategies);
$isValid = $productValidationStrategyContext->validateProduct($productType, $productData);
if ($isValid === false) {
throw new Exception('Bad Request Exception');
}
$productInsertStrategyContext = new ProductInsertStrategyContext($availableProductInsertStrategies);
$productInsertStrategyContext->insertProduct($productType, $productData);
print_r(PHP_EOL);
print_r(sprintf('The Product type, %s Product has been inserted', $productType));
print_r(PHP_EOL);

Answer 3

In your class, you have a "master method" productValidation that does validation for all three product types. Imagine scaling that up to 30 products. Then: One method, one concern!
From your form illustration it's evident that only one type of product will be submitted at a given time. Now, you already have separate methods for insert(Book|DVD|Furniture). The logical next step is to remove the validation logic from your "bulk method" and create separate validate(Book|DVD|Furniture) methods. You should definitely not use a ton of conditional expressions within a single method to accomplish polymorphic handling!
First off, I would reduce the arguments in your productValidation method and simply pass in a single array (say, $data) with whatever possible values. These will be sorted out by your validator methods. If we must adhere to "no conditional expressions for product validation", here's a staple construct (in my books anyway) that you can use for polymorphic method calls:
public function productValidation(array $data, string $prodType) {
$validatorMethod = 'validate' . $prodType; // = validateBook, etc.
$isValid = $this->$validatorMethod($data);
if($isValid) {
$insertMethod = 'insert' . $prodType;
$this->$insertMethod($data);
}
///...
}
This approach will make it easy for you to add new product types down the road, simply by adding new methods with appropriate names. You will want to check for valid product types at the beginning of your validator, for example by listing them in a class property:
class Product_Validation
{
// Types that match your methods;
// or UI-names mapping to method-names (key/value pairs)
public array $prodTypes = ['Book', 'DVD', 'Furniture'];
...
// and in your validator master method:
if(!in_array($prodType, $this->prodTypes)) {
protest('Invalid Product Type'); // however you handle errors
}
If you have attributes common to all products (like name, price) that you want validated, delegate them into a separate validator method validateCommon() that you call before the product-specific validators. You can remove the error check logic from your insert* methods, which should only ever be called if the validation passes to begin with.
Also consider creating coherent methods for user input error handling, and remember that classes can have properties. They're quite useful e.g. for containing the object state (rather than passing all data around in return statements). On that note, consider storing your errors etc. feedback into the object's properties, and writing the them into a session in one place when you're done (if you must, but I bet you don't, especially don't abuse sessions as global variables).
In other notes, some of your ternary expressions are really not an improvement over if/elseif/else statements. Especially when they are chained, and have no brackets, it becomes extremely unreadable. (Nested ternary expressions without brackets are deprecated as of PHP 7.4.) In further best practices, a file with a class should not cause side effects (in your case, with session_start()). It's better to separate your symbols (classes, functions, traits, etc.) from your processes/operations in the interest of code reusability.
On a general note of restructuring, you might consider separating your concerns further, whether e.g. by means of a bookClass with validate and insert methods, or by having validateClass and insertClass with methods for each product type, or by whatever other design that doesn't bundle everything into one class and especially not one master method.

Answer 4

It depends on the conditions.
You can use associative array to avoid some if or case.
Ex:
Instead of a switch like this
switch ($i) {
case 0:
echo "i equals 0";
break;
case 1:
echo "i equals 1";
break;
case 2:
echo "i equals 2";
break;
case 'Cat':
echo "The best";
break;
}
You can write
$iValues = [0 => 'i equal 0', 1 => 'i equal 1', 2 => 'i equal 2', 'Cat' => 'The best'];
echo $iValues['Cat'];