Using the Symfony Validator component as a standalone library

Sometimes I need to build some scripts without using a full framework like Symfony. The good news is that you can use individual components from Symfony. Most often I will be using the HTTPFoundation component, but for today I want to build a CLI script so no need for HTTPFoundation.
I  will be writing a small command line script to read and validate a  CSV file. For the  validation part I will be using the Symfony Validator Component,

Source of inspiration: https://blog.tinned-software.net/using-the-symfony-validator-as-a-standalone-component/


First step, install Symfony Validator using Composer:

                          composer require symfony/validator

and require the autoloader created by Composer.

<?php

require_once 'vendor/autoload.php';
require_once 'Loader.php';

use Symfony\Component\Validator\Validation;

$file = "someFile.csv";


$outputFile = "errorsLog" . "_" . time() . ".txt";
  
$validator = Validation::createValidatorBuilder()
 ->addMethodMapping('loadValidatorMetadata')
 ->getValidator()
;

$loader = new Loader($file, $outputFile, $validator);
$loader->load();

I will pass to my Loader class constructor the CSV file to be read, the file where I want to save the output and an instance of the Symfony validator.

The CSV file is read line by line, and from each line I will be creating a Row object. The validator will validate the Row object against the rules (constraints).
In the Row class I will add the method "loadValidatorMetada" mentioned when instantiating the Validator. I've added several validations for better examplification:

<?php

use Symfony\Component\Validator\Constraints as Assert;
use Symfony\Component\Validator\Mapping\ClassMetadata;


class Row
{
    private $id;         
    private $name;   
    private $personalNumber;    
    private $CountryCode;  

    public function __construct($rowNumber, $data)
    {
        $this->id = $rowNumber;
        $this->name= $data[0];
        $this->personalNumber = $data[2];
        $this->countryCode = $data[1];
    }
 
 
    /**
     * This method is where you define your validation rules.
    */
    public static function loadValidatorMetadata(ClassMetadata $metadata)
    {
        //Name 

        $metadata->addPropertyConstraint('name', new Assert\NotBlank());

        //Personal number
        $metadata->addPropertyConstraint('personalNumber', new Assert\NotBlank());

        $metadata->addPropertyConstraint('personalNumber', new Assert\Type(array(
            'type'    => 'digit',
            'message' => 'The value {{ value }} is not a valid personal number.',
         )));
  
         //Country code
         $metadata->addPropertyConstraint('countryCode', new Assert\NotBlank());
         $metadata->addPropertyConstraint('countryCode', new Assert\Choice(array(
            'choices' => array('DE', 'AT', 'LU', 'ES', 'FR', 'BE', 'NO', 'SI', 'SE', 'IT', 'DK'),
            'message' => '{{ value }} is not a valid country code!',
          )));
  
     }
}

When validating a Row object against these constraints an array of Errors will be returned by the Validator. Below is the Loader class.

<?php

require_once 'Row.php';


class Loader
{
 private $fileName;
 private $validator;
 private $outputFile;
 
 public function __construct($fileName, $outputFile, $validator)
 {
  $this->fileName = $fileName;
  $this->outputFile = $outputFile;
  $this->validator = $validator;

 }
 
 public function load()
 {
  $file_handle = fopen($this->fileName, "r");
  $fileOutputHandle = fopen($this->outputFile, "w");
  
  /* 
   * Keep track of the current row in .csv file
   */
  $rowNumber=1;
  
  /* 
   * Read the file line by line
   */
  while (!feof($file_handle) ) {

   $line_of_text = fgetcsv($file_handle, 0);
   
   if ($rowNumber === 1) {
    
      /*
       * Ignore the first row from file as it contains headers
       */
     
   } else {
       $row = new Row($rowNumber, $line_of_text);    
       $this->validateRow($row, $fileOutputHandle); 
   }
   
   $rowNumber++;
  }
  fclose($file_handle);
  fclose($fileOutputHandle);
 }
 
 
 public function validateRow(Row $row, $fileOutputHandle)
 {
  $errors = $this->validator->validate($row);
  
  foreach ($errors as $error) {
   $errorMsg = "At row:" 
      . $error->getRoot()->getId() 
      . "- Property: " 
      . $error->getPropertyPath()
      . ' - Message: ' 
      . $error->getMessage()
      . "\n";
   
   fwrite($fileOutputHandle, $errorMsg);

  }
 }
}