PHP writting 'null' for JSON file written by Python - php

Question

I am trying to send JSON information from Python to PHP through a JSON file data.json, based on the content of the Stack Overflow question/answer here. I am running this code all on an Apache web server on Raspberry Pi 3.
Here is my code:
Python
import sys, json, random # I know I don't need sys and random to run this, but I was using these in my previous code.
data = {'fruit':['oranges', 'apples', 'peaches'], 'age':12}
with open('data.json', 'w') as outfile:
json.dump(data, outfile)
When run, this program worked fine and exited with code 0.
JSON file
{"age": 12, "fruit": ["oranges", "apples", "peaches"]}
As you can see, my Python worked perfectly and the output is identical to the data variable in my python code. On second thought, the order is backward, although I don't think this matters.
PHP
Now, this is where the problem is:
<?php
$string = file_get_contents("data.json");
$json_a = json_decode($string, true);
$arr = array();
foreach ($json_a as $key) {
array_push($arr,json_decode($key[0],true));
}
echo json_encode($arr);
?>
When run, the program exited with code 0 but outputed:
[null,null]
Does anyone have an idea why this is, or is this just the way JSON works?

Answer 1

The original code with issues:
<?php
$string = file_get_contents("data.json");
$json_a = json_decode($string, true);
$arr = array();
foreach ($json_a as $key) {
// No need to use json_decode again
// as it is already converted to an array
// by the inital json decode statement
array_push($arr,json_decode($key[0],true));
}
echo json_encode($arr);
?>
Pretty printed PHP Array which is stored inside $json_a:
Array
(
[age] => 12
[fruit] => Array
(
[0] => oranges
[1] => apples
[2] => peaches
)
)
The problem:
In the original script, json_decode was used on an already decoded variable/array which returned nothing and hence null was appended to your list.
Code walkthrough:
During the first iteration of the foreach loop,
$key will have the value 12 - which is a string
During the second iteration of the foreach loop,
$key will have the value - which is an Array
Array
(
[0] => oranges
[1] => apples
[2] => peaches
)
The corrected code for printing all the fruits:
<?php
$string = file_get_contents("data.json");
$json_a = json_decode($string, true);
$arr = array();
foreach ($json_a['fruit'] as $key) {
array_push($arr,$key);
}
echo json_encode($arr);
?>
The above snippet returns ["oranges","apples","peaches"]