Asked  7 Months ago    Answers:  5   Viewed   91 times

Using PHP, I would like to make a while loop that reads a large file and sends the current line number when requested. Using Ajax, I'd like to get the current line count and print it out onto a page. Using html buttons, I'd like to be able to click and activate or terminate a javascript thread that runs only ONCE and calls the ajax method.

I have given it a shot but for some reason, nothing prints unless I comment out the echo str_repeat(' ',1024*64); function and when it's commented out, it shows the entire loop result:

1 row(s) processed.2 row(s) processed.3 row(s) processed.4 row(s) processed.5 row(s) processed.6 row(s) processed.7 row(s) processed.8 row(s) processed.9 row(s) processed.10 row(s) processed.

In a single line instead of showing them in separate lines like:

1 row(s) processed.
2 row(s) processed.
3 row(s) processed.
4 row(s) processed.
5 row(s) processed.
6 row(s) processed.
7 row(s) processed.
8 row(s) processed.
9 row(s) processed.
10 row(s) processed.

Also I'm not sure how to terminate the JavaScript thread. So 2 problems in total:

 1. It's returning the entire While loop object at once instead of each time it loops.
 2. I'm not sure how to terminate the JQuery thread.

Any ideas? Below is my code so far.

msgserv.php

<?php

//Initiate Line Count
$lineCount = 0;

// Set current filename
$file = "test.txt";

// Open the file for reading
$handle = fopen($file, "r");

//Change Execution Time to 8 Hours
ini_set('max_execution_time', 28800);

// Loop through the file until you reach the last line
while (!feof($handle)) {

    // Read a line
    $line = fgets($handle);

    // Increment the counter
    $lineCount++;

    // Javascript for updating the progress bar and information
    echo $lineCount . " row(s) processed.";

    // This is for the buffer achieve the minimum size in order to flush data
    //echo str_repeat(' ',1024*64);

    // Send output to browser immediately
    flush();

    // Sleep one second so we can see the delay
    //usleep(100);
}

// Release the file for access
fclose($handle);

?>

asd.html

<html>
    <head>
        <script src="http://code.jquery.com/jquery-latest.min.js" type="text/javascript" charset="utf-8"></script>

        <style type="text/css" media="screen">
            .msg{ background:#aaa;padding:.2em; border-bottom:1px #000 solid}
            .new{ background-color:#3B9957;}
            .error{ background-color:#992E36;}
        </style>

    </head>
    <body>

    <center>
        <fieldset>
            <legend>Count lines in a file</legend>
            <input type="button" value="Start Counting" id="startCounting" />
            <input type="button" value="Stop Counting!" onclick="clearInterval(not-Sure-How-To-Reference-Jquery-Thread);" />
        </fieldset>
    </center>

    <div id="messages">
        <div class="msg old"></div>
    </div>

    <script type="text/javascript" charset="utf-8">
        function addmsg(type, msg){
            /* Simple helper to add a div.
        type is the name of a CSS class (old/new/error).
        msg is the contents of the div */
            $("#messages").append(
            "<div class='msg "+ type +"'>"+ msg +"</div>"
        );
        }

        function waitForMsg(){
            /* This requests the url "msgsrv.php"
        When it complete (or errors)*/
            $.ajax({
                type: "GET",
                url: "msgsrv.php",
                async: true, /* If set to non-async, browser shows page as "Loading.."*/
                cache: false,
                timeout:2880000, /* Timeout in ms set to 8 hours */

                success: function(data){ /* called when request to barge.php completes */
                    addmsg("new", data); /* Add response to a .msg div (with the "new" class)*/
                    setTimeout(
                    'waitForMsg()', /* Request next message */
                    1000 /* ..after 1 seconds */
                );
                },
                error: function(XMLHttpRequest, textStatus, errorThrown){
                    addmsg("error", textStatus + " (" + errorThrown + ")");
                    setTimeout(
                    'waitForMsg()', /* Try again after.. */
                    "15000"); /* milliseconds (15seconds) */
                },
            });
        };

        $('#startCounting').click(function() {
            waitForMsg();
        });
    </script>

</body>
</html>

test.txt

1
2
3
4
5
6
7
8
9
10

 Answers

18

Using:

  • jQuery kill ajax request
  • ignore_user_abort()
  • ob_flush()

should do all you need in one php thread

EDIT

Take a look at nickb's answer, if you're looking for a way how to do this simply it would be following algorithm:

  1. javascript opens process.php via ajax (which will do all the work AND print status reports), you have to look up whether jQuery ajax supports continuous loading
  2. if user decides to stop refreshes you'll kill loading as show in provided link

In process.php:

ignore_user_abort(); // Script will finish in background
while(...){
  echo "Page: $in";
  ob_flush();
}

EDIT 2 requested example (bit of different and ugly, but simple). test_process.php:

// This script will write numbers from 1 to 100 into file (whatever happens)
// And sends continuously info to user
$fp = fopen( '/tmp/output.txt', 'w') or die('Failed to open');
set_time_limit( 120);
ignore_user_abort(true);

for( $i = 0; $i < 100; $i++){
    echo "<script type="text/javascript">parent.document.getElementById( 'foo').innerHTML += 'Line $i<br />';</script>";
    echo str_repeat( ' ', 2048);
    flush();
    ob_flush();
    sleep(1);
    fwrite( $fp, "$in");
}

fclose( $fp);

And main html page:

<iframe id="loadarea"></iframe><br />
<script>
function helper() {
    document.getElementById('loadarea').src = 'test_process.php';
}
function kill() {
    document.getElementById('loadarea').src = '';
}
</script>

<input type="button" onclick="helper()" value="Start">
<input type="button" onclick="kill()" value="Stop">
<div id="foo"></div>

After hitting start lines as:

Line 1
Line 2

Appeared in the div #foo. When I hit Stop, they stopped appearing but script finished in background and written all 100 numbers into file.

If you hit Start again script starts to execute from the begging (rewrite file) so would parallel request do.

For more info on http streaming see this link

Wednesday, March 31, 2021
 
tadman
answered 7 Months ago
48

You can use the strtr() function in PHP to pass in a key => value pair of replacement rules:

$data = mysql_query('SELECT * FROM todolist WHERE date > CURDATE()') or die(mysql_error());

// Array of replacement rules. Keys of the array are strings to be replaced.
// Corresponding values of the keys are the replacement strings
$trans = array(
    'stringtoreplace1' => 'replacedstring1',
    'stringtoreplace2' => 'replacedstring2',
    'stringtoreplace3' => 'replacedstring3'
);

while($info = mysql_fetch_array($data)) 
{
    print strtr($info['thingtobedone'], $trans) . ' with ' . $info['persontomeet'] . '<br />';
}

Assuming thingtobedone is the column you want to make the replacements on.

Then when you call strtr($info['thingtobedone'], $trans), the function will take the string and replace all occurances of every key value in the $trans array with their corresponding values. It's a nice way to make many string-replacements all at once.

Wednesday, March 31, 2021
 
waylaidwanderer
answered 7 Months ago
75

One query is fine. As you have it, and probably the better opton. You have to work out which is more efficient, to let MySQL take the strain, or the network and PHP take the strain. It's a lot better to let PHP take the strain than MySQL, but where MySQL has "inbuilt" features, such as the grouping you desire, then leave the MySQL and save the network traffic.

To make this work: add "ORDER BY p.post_id, pc.comment_id" to your query - this gets the results in order.

Then, if you must build into an array (although you may be able to process directly without using an array, the method would be similar):

$lastPostID = 0;
while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
    if ($lastPostID <> $row['post_id']) {
        $lastPostID  = $row['post_id'];
        $answers[$lastPostID] = array('post_id' => $row['post_id'],
                                      'author_id' => $row['author_id'],
                                      etc
                                      'comments' => array() );
    }
    $answers[$lastPostID]['comments'][] = array('comment_id' => $row['comment_id'], 'coment' => $row['comment'] etc);
}
Saturday, May 29, 2021
 
PHLAK
answered 5 Months ago
26

I need to query by userId WHERE departmentId = XXXX and SUM each of their totalHours that exist, without neglecting the userId without any record in attendance.

To show the hours for all users in a given department, even users w/o rows in the attendance table, use a LEFT JOIN

Use (CAST(totalHours AS UNSIGNED) % 100)/60 + FLOOR(CAST(totalHours AS UNSIGNED)/100) to convert your varchar hours+minutes to a single number of hours.

$query = "SELECT u.id, 
SUM((CAST(totalHours AS UNSIGNED) % 100)/60 + FLOOR(CAST(totalHours AS UNSIGNED)/100)) grandTotal
FROM user u
LEFT JOIN attendance a
ON u.id = a.userId
WHERE u.departmentId = 2
GROUP BY u.id";

$result = mysqli_query($con,$query);

while($row = mysqli_fetch_array($result)) {
    print $row['id'] . ' ' . $row['grandTotal'];
}
Saturday, May 29, 2021
 
SheppardDigital
answered 5 Months ago
80

Why not do the following? This will open it and close it after the third post. Then close the ending div in the event there is not a multiple of 3 to display.

$i = 1;
//added before to ensure it gets opened
echo '<div>';
if ( $wp_query->have_posts() ) : while ( $wp_query->have_posts() ) : $wp_query->the_post();
     // post stuff...

     // if multiple of 3 close div and open a new div
     if($i % 3 == 0) {echo '</div><div>';}

$i++; endwhile; endif;
//make sure open div is closed
echo '</div>';

In case you didn't know, % is the modus operator will return the remainder after the two numbers are divided.

Monday, July 12, 2021
 
mnagel
answered 3 Months ago
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