mysql foreach fwrite - php

Question

I use some code here, transfer mysql query data into json data and write into a file. where is the problem? why the file is zero kb?
while($row = mysql_fetch_array($Query)){
$arr = array ('name'=>$row['name']);
$jsondata = json_encode($arr);
$countfile="data.txt";
if(!file_exists($countfile))
{
fopen($countfile,"w");
}
$fp = fopen($countfile, 'r');
fwrite($fp, $jsondata);
fclose($fp);
}

Answer 1

Several things.
You dont need (and should avoid) to open the file in every iteration
You open the file read-only (r)
At all something like this should do it
$countfile="data.txt";
$fp = fopen($countfile, 'w');
while($row = mysql_fetch_array($Query))
{
$arr = array ('name'=>$row['name']);
$jsondata = json_encode($arr);
fwrite($fp, $jsondata);
}
fclose($fp);
Additional you append separate json structures into the file, what is probably not, what you want. You should first collect all you want to store into one json structure and save it then
$data = array();
while($row = mysql_fetch_array($Query))
{
$data[] = array ('name'=>$row['name']);
}
file_put_contents('data.txt', json_encode($data));
This feels more like what you are probably looking for.

Answer 2

Because you're reopening the file as read only
$fp = fopen($countfile, 'r');
try
$fp = fopen($countfile, 'w'); // to write
or
$fp = fopen($countfile, 'a'); // to append
you could also open the file for writing at the start, append your rows in a variable and then write it all together to the file.
$countfile="data.txt";
$fp = fopen($countfile, 'w');
while($row = mysql_fetch_array($Query))
{
$arr = array ('name'=>$row['name']);
$jsondata .= json_encode($arr) . "\n";
}
fwrite($fp, $jsondata);
fclose($fp);

Answer 3

You are opening the file read-only. You probably want 'w' or 'r+'.

Answer 4

You are opening the file for reading only
$fp = fopen($countfile, 'r');
You also dont need
if(!file_exists($countfile))
{
fopen($countfile,"w");
}
just use:
$fp = fopen($countfile, 'w');