Update values in 2 different .json files using PHP - php

Question

I have 2 .json files, one containing questions and answers with categories and one containing the categories. Here are small parts of the .json files:
category.json
[{
"category": "Algemeen"
}]
questions.json
[{
"category": "Algemeen",
"question": "123",
"answer": "123",
"date": "03-12-18 08:48:16"
}]
I have created an overview for the categories, where I can add, edit and delete a category. I have also created an overview for the questions and answers.
When editing the category in the category overview, it will post this into the .json file using the following code:
<?php
//get the index from URL
$index = $_GET['index'];
//get json data
$data = file_get_contents('category.json');
$data_array = json_decode($data);
//assign the data to selected index
$row = $data_array[$index];
?>
<?php
if(isset($_POST['save'])){
//set the updated values
$input = array(
'category' => $_POST['category'],
);
//update the selected index
$data_array[$index] = $input;
//encode back to json
$data = json_encode($data_array, JSON_PRETTY_PRINT);
file_put_contents('category.json', $data);
header('location: category.php');
}
?>
When "Algemeen" is edited into "Algemeen1" using my simple form with save button, this will edit category.json using the code above. This will change into:
[{
"category": "Algemeen1"
}]
However, the goal is to have the categories "synced", so that when you edit any category that also exists in questions.json, it also edits the value of category in questions.json. This has to result into:
[{
"category": "Algemeen1",
"question": "123",
"answer": "123",
"date": "03-12-18 08:48:16"
}]
How can I do this?

Answer 1

I would do something like this:
<?php
//get the index from URL
$index = $_GET['index'];
//get json data
$category_data = file_get_contents('category.json');
$category_data_array = json_decode($data);
$questions_data = file_get_contents('questions.json');
$questions_data_array = json_decode($data);
// get the old category name
$row = $category_data_array[$index];
$old_category = $row->category;
?>
<?php
if(isset($_POST['save'])){
//set the updated values
$input = array(
'category' => $_POST['category'],
);
//update the selected index
$category_data_array[$index] = $input;
// find old category, make new
foreach($questions_data_array as $question){
if ($question->category == $old_category) {
$question->category = $_POST['category'];
break;
}
}
//encode back to json
$category_data = json_encode($category_data_array, JSON_PRETTY_PRINT);
file_put_contents('category.json', $category_data);
$questions_data = json_encode($questions_data_array, JSON_PRETTY_PRINT);
file_put_contents('questions.json', $questions_data);
header('location: category.php');
}
?>
Caveat: I did not test this code. It's like pseudo-code in the shape of actual code.