Reading config.json file in PHP

Question

I would like to ask what could be the problem with my code.

The situation is that I would like to read some data from a config.json file, and I have to use it in a class. My idea is to use a constructor function, but the script does not do anything with the values.

My code:

<?php

class test
{ 

private $json;
private $config;
private $xmlFiles;
private $modifiedElement;
private $modifiedElement2;
private $exchangeValue;
private $exchangeValue2;
private $inputFolderPath;
private $outputFolderPath;
private $outputFileName;


   public function __construct()
   {
      $this->setXmlFiles();
      $this->createFolder();
      $this->json = file_get_contents('config.json');
      $this->config = json_decode($json,true);
      $this->xmlFiles = array(); 
      $this->modifiedElement = $this->config->modifiedElement1; 
      $this->modifiedElement2 = $this->config->modifiedElement2; 
      $this->exchangeValue = $this->config->exchangeValue1; 
      $this->exchangeValue2 = $this->config->exchangeValue2; 
      $this->inputFolderPath = $this->config->inputFolderPath; 
      $this->outputFolderPath = $this->config->outputFolderPath; 
      $this->outputFileName = null; 

   }

On my config.json there are some test data:

{
  "modifiedElement1" : "11", 
  "modifiedElement2" : "22",
  "exchangeValue1" : "11",
  "exchangeValue2" : "333",
  "inputFolderPath" : "input/",
  "outputFolderPath" : "output/"
}

Can you help me with this? I tried to declare the variables as public instead of private, did not work anyway unfortunately.

Answer 1

The code has a couple of fairly low-level issues:

1. $json is not defined. You need to use $this->json since that's where you assigned the JSON data you read in from the file. This should be generating at least one warning in your code, but you didn't mention it - make sure you always have PHP error reporting switched on for debugging.

2. As per the documentation, the true argument you've passed to json_decode makes it returns an associative array instead of an object. Therefore the code later on trying to access it as if it's an object should generate some warnings/errors - but only if you first decode a variable which actually exists! Instead, you need to use json_decode without the true argument...and always read the manual!

Change

$this->config = json_decode($json,true);

to

$this->config = json_decode($this->json);

in order to resolve those two issues.

Live demo: https://3v4l.org/cfBos