PHP - How to update JSON data in a txt file? - php

Question

Here is a JSON data example saved in a file data.txt
[
{"name":"yekky"},
{"name":"mussie"},
{"name":"jessecasicas"}
...// many rows
]
I would like to update the file so it will look like this:
[
{"name":"yekky","num":"1"},
{"name":"mussie","num":"2"},
{"name":"jessecasicas","num":"3"}
...// many rows
]
This is what I have got so far:
$json_data = file_get_contents('data.txt');
// What goes here?
And how do I count how many rows there are in the JSON tree?

Answer 1

Use json_decode() to decode the JSON data in a PHP array, manipulate the PHP array, then re-encode the data with json_encode().
For example:
$json_data = json_decode(file_get_contents('data.txt'), true);
for ($i = 0, $len = count($json_data); $i < $len; ++$i) {
$json_data[$i]['num'] = (string) ($i + 1);
}
file_put_contents('data.txt', json_encode($json_data));

Answer 2

You should use the PHP JSON library for such tasks. For example, after having read your JSON data from the file, do something like:
$json = json_decode($json_data);
$itemCount = count($json);
After having modified your JSON data, just encode it again:
$json_data = json_encode($json);
Also, you seem to want to beatify your JSON data. My advise is to just use whatever comes out of json_encode and save that to your file, because it will probably be the smallest (in file size) possible representation of your JSON data.
If you format it in a way readable for humans, you've got lots of extra spaces / tabs / line-breaks which increase file size and parsing time.
If you need to read it yourself, you can still beautify your JSON data by hand.

Answer 3

$file = 'data.txt';
$data = json_decode(file_get_contents($file));
foreach ($data as $key => $obj) {
$obj->num = (string)($key+1);
}
file_put_contents($file, json_encode($data));