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));