PHP: How can I cache a page using output buffer?

Question

I'm trying to cache a page that gets/processes data from very slow API's - so I can load it quickly to the user. But for some reason the output buffer is empty?

<?php

ob_start();

// here I have php scripting accessing api's for information

?>


// Here I have HTML content with some php conditions and echos to filter and display the gathered information

// then I try to save the buffered page to the database:

<?php

//connect to database
$page = ob_get_contents();

mysql_query("UPDATE `pages` SET `page_cache` = '" . $page . "' WHERE `page_id` = '" . $page_id . "'");

?>

Any help would be appreciated!

What is the output if you `var_dump($page)` instead of issuing a query? — Jeff Lambert, May 21 '12 at 15:16
You should call `ob_end_clean()` at the end of working with output buffer. Try to comment `ob_start()` - do you see any output? — Jan Turoň, May 21 '12 at 15:18
What Jan means is what do you see if you don't buffer anything, but just display the page. — Cylindric, May 21 '12 at 15:27
the page displays fine with or without the buffer - could the issue be to do with the very slow API / processing of the large array returned? it takes about 15-20 seconds to make the page! — Joe, May 21 '12 at 15:33
Your API may have another `ob_start(); ... ob_end_clean();` or something??? — bitoshi.n, May 21 '12 at 16:10
Hi sorry var_dump($page) gets bool(false) does that make any difference? — Joe, May 21 '12 at 17:24

score 1 · Accepted Answer · answered May 21 '12 at 15:14

1

Are you making sure your $page contains only database-safe characters?

What happens if the output contains a single ' for example?

answered May 21 '12 at 15:14

Cylindric

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I try to echo or print_r $page before it gets to the database bit and it prints nothing – Joe May 21 '12 at 15:19
Hmm okay, so it doesn't seem to be a database query error. (Although you **do** need to sort that too) – Cylindric May 21 '12 at 15:27
cool thanks for the heads up for when I hopefully get this working :) – Joe May 21 '12 at 15:34

score 0 · Answer 2 · answered May 21 '12 at 15:25

0

You may want to let MySQL encode that $page variable:

mysql_query(sprintf(
    "UPDATE `pages` SET `page_cache`='%s' WHERE `page_id`=%s",
    mysql_real_escape_string( $page ),
    intval( $page_id )  // assuming it's an int
));

answered May 21 '12 at 15:25

pp19dd

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@Joe, this is basically what I was talking about to keep your inserts clean :) – Cylindric May 21 '12 at 15:47

score 0 · Answer 3 · answered May 21 '12 at 22:14

Check whether output buffering is on in your /etc/php.ini: http://www.php.net/manual/en/outcontrol.configuration.php

Also, do an:

<?php echo ob_get_contents(); ?>

If it prints FALSE, then output buffering may not be enabled: http://php.net/manual/en/function.ob-get-contents.php

PHP: How can I cache a page using output buffer?

3 Answers3