Change a value of json variable in a php file

Question

Hi i have a php file that contain json value. I want to change the value of json variable .But i am not sure how t do that .

my-file.php

<?
    $json_data;
    $json_varible = json_decode('{"pen_color":"red","book_size":"large","book_color":"red", etc etc }', true);
    ....
?>

Now I want to change the value of pen_color to green . Please note there are many parameters in json_decode

So i write following

//read the entire string
$str=file_get_contents('my-file.php');
$old_value= "red";
$new_value = "green";

//replace something in the file string - this is a VERY simple example
$str=str_replace($old_value, $new_value,$str);

file_put_contents('my-file.php', $str);

I am sure that this code is wrong. Please help me to solve the issue. I want t change pen_color to green

Answer 1

May be it is that you want

$json_variable = json_decode('{"pen_color":"red","book_size":"large","book_color":"red"}', true);
$json_variable['pen_color'] = 'green';
$json_value = json_encode($json_variable);

file_put_contents('my-file.php', $json_value );