Writing to JSON file from PHP fseek()/rewind() not working - php

Question

I'm working on a logger class , the JSON that is being added has the following format
{"log_owner" : "test123","log_message" : "Has logged in","log_timestamp" : "1397921556","log_type" : "1"}
To retrieve it I require square brackets around all the different JSON Objects as the following :
[
{"log_owner" : "test456","log_message" : "Has logged in","log_timestamp" : "1397921856","log_type" : "2"}
{"log_owner" : "test123","log_message" : "Has logged in","log_timestamp" : "1397921556","log_type" : "1"}
]
I've managed to insert it at the beginning of the file whenever the file didn't existed, but the main issue resides on moving the closing bracket to the end of the file as I'm adding new objects , I've tried to move my file pointer 2 places before to be able to overwrite the last bracket keep adding the closing bracket to every new entry, I'm trying to accomplish this with :
if(!$content_new) {
$pos=ftell($handle);
fseek($handle,$pos-2);
}
fwrite($handle, $content);
fclose($handle);
But seems that It does not work with .json files, as I'm not able to move my file pointer to any other line or rewind it.
How could I accomplish this ? Any kind of guidance or suggestions for improvement is highly appreciated .
Thank you.

Answer 1

Direct solution for your problem - quick and dirty.
<?php
function writeLog($path, $newLine)
{
$exists = file_exists($path);
$handle = fopen($path, 'c');
if (!$exists) {
// first write to log file
$line = "[" . PHP_EOL . $newLine . PHP_EOL . "]";
} else {
// file exists so it has one or more logged lines
$line = "," . PHP_EOL . $newLine . PHP_EOL . "]";
fseek($handle , -(strlen(PHP_EOL) + 1) , SEEK_END);
}
fwrite($handle, $line);
fclose($handle);
}
$path = __DIR__ . '/file.json';
// delete file if exists - for tests
if (file_exists($path)) {
unlink($path);
}
$line = '{"log_owner" : "test123","log_message" : "Has logged in","log_timestamp" : "1397921556","log_type" : "1"}';
for ($i = 0; $i < 10; $i++) {
writeLog($path, $line);
}
Problems
concurrency
scaling
JSON is not easiest to edit and view
no easy filtering
Use CSV, output JSON
<?php
function writeLogCSV($path, $newLine)
{
$handle = fopen($path, 'a');
fputcsv($handle, $newLine);
fclose($handle);
}
function readLogCsv ($path)
{
$handle = fopen($path, 'r');
$rows = [];
while (false !== ($line = fgetcsv($handle))) {
$rows[] = array_combine(
["log_owner", "log_message", "log_timestamp", "log_type"],
$line
);
}
fclose($handle);
echo json_encode($rows);
}
$path = __DIR__ . '/file.csv';
// delete file if exists - for tests
if (file_exists($path)) {
unlink($path);
}
$line = ["test123", "Has logged in", "1397921556", "1"];
for ($i = 0; $i < 10; $i++) {
writeLogCSV($path, $line);
}
readLogCsv($path);
Good parts:
easy to read and write
Problems:
scaling
concurrency
no easy filtering
Store your log in database or use logging service, output JSON
Good parts
no concurrency issues
easy filtering
speed
good for scaling