how to add multiple values from checkbox into .txt file - php

Question

For a simple voting system, i put the values into a .txt file.
This is the array i use:
$quickpolloptions = ['Mozilla', 'Chrome', 'Opera', 'IE', 'Safari'];
This is the form:
<form method="post" id="quickpoll">
foreach ($quickpolloptions as $key => $value) {
echo "<tr>";
echo "<td>";
echo "<label>$value</label>";
echo "</td>";
echo "<td>";
echo "<input type='checkbox' name='checkboxvote[]' value='$key'><br>";
echo "</td>";
echo "</tr>";
}
<input type="submit" value="Submit">
</form>
This is how i store the data:
$result_file = "data/vote_result.txt";
if (file_exists($result_file)) {
$results = explode(',', file_get_contents('data/vote_result.txt'));
} else {
// start with zeros if you don't have a file yet
$results = array_fill(0, count($quickpolloptions), 0);
}
// below i am trying to read each value fromn checkbox and store in .txt file
if (isset($_POST['checkboxvote'])) {
foreach ($_POST['checkboxvote'] as $checkbox) {
$results[$_POST['checkboxvote']]++;
file_put_contents('data/vote_result.txt', implode(',', $results));
}
}
So i do not succeed in the last part: to put multiple values in the txt file.
How can i do that?

Answer 1

Use the $checkbox variable as the key to $results when incrementing the values. Also, don't write to the file inside the loop. Just update the array and then write to the file once.
if (isset($_POST['checkboxvote'])) {
foreach ($_POST['checkboxvote'] as $checkbox) {
$results[$checkbox]++;
}
file_put_contents('data/vote_result.txt', implode(',', $results));
}

Answer 2

In your foreach loop you are looping over $_POST['checkboxvote'] which is correct. However $checkbox is the element.
Second, you are inserting the value into the index of $results, you need them as the data of the results so implode will combine them.
Lastly, you should call file_put_contents() outside of your foreach loop. If you call it multiple times it will appear to work correctly but it will be wasting time by overwriting your file each loop.
foreach ($_POST['checkboxvote'] as $checkbox) {
$results[] = $checkbox;
file_put_contents('data/vote_result.txt', implode(',', $results));
}
or
foreach ($_POST['checkboxvote'] as $key => $checkbox) {
$results[] = $_POST['checkboxvote'][$key];
file_put_contents('data/vote_result.txt', implode(',', $results));
}

Answer 3

I think $results[$_POST['checkboxvote']]++; should be $results[$checkbox]++;
Note that your implementation is susceptible to race conditions if two people vote at the same time.
You should use file locks or consider an RDBMS with transaction protection.
Example:
if (isset($_POST['checkboxvote'])) {
/* lock the file to prevent a race condition */
$file_handle = fopen($result_file, 'a+');
$locked = flock($file_handle, LOCK_EX);
/* retrieve the results now that we are locked */
$results = fgets($file_handle);
if ($results !== false) {
$results = explode(',', $results);
} else {
$results = array_fill(0, count($quickpolloptions), 0);
}
/* update the results */
foreach ($_POST['checkboxvote'] as $checkbox) {
$results[$checkbox]]++;
}
/* write them to the file and unlock */
ftruncate($file_handle, 0);
fputs($file_handle, implode(',', $results));
flock($file_handle, LOCK_UN);
fclose($file_handle);
}

Answer 4

I am assuming the second code block is an HTTP endpoint which you hit to save data into your vote_result.txt file.
You're getting the contents of what's currently in that file right now and assigning it to the variable $result - something which you don't need to do since you never actually return it as a response from the script.
All you need is the code that will take the POST parameter array of checkboxvote and save it as a string with commas separating the values. Something like:
if(isset($_POST['checkboxvote'])){
file_put_contents('data/vote_result.txt', implode(',', $_POST['checkboxvote']));
}
You don't need the for loop when writing to your file since implode() already breaks down your array into one string.
Now, when you POST to your script with the following parameter:
checkboxvote[]='owl'
checkboxvote[]='chicken'
checkboxvote[]='deer'
Your vote_result.txt will look like:
owl,chicken,deer