Re: [PHP] Is it possible to stop an image from being cached?
Dan wrote: ... You should also look at this: http://www.mnot.net/cache_docs/ Very informative. -- Richard Heyes +44 (0)844 801 1072 http://www.websupportsolutions.co.uk Knowledge Base and HelpDesk software that can cut the cost of online support -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
RE: [PHP] Is it possible to stop an image from being cached?
Solution 1: Send a header() that avoids caching (can't remember it exactly) Solution 2: Call the image like this: img src=image.jpg?arandomstringhereeachtime Or if you were creating it with a php script: img src=image.php?img=image.jpgarandomstringhereeachtime My preferred way of doing it, and making sure its reloaded each time is to do it this way... the U variable pretty much guarantees a random string each time its loaded. image.jpg?.date(U). Regards Chris Aitken The Web Hub Designer and Programmer Phone : 02 4648 0808 Mobile : 0411 132 075 - Making The Web Work The Web Hub http://www.thewebhub.com.au/ [EMAIL PROTECTED] - Confidentiality Statement: This message is intended only for the use of the Addressee and may contain information that is PRIVILEDGED and CONFIDENTIAL. If you are not the intended recipient, dissemination of this communication is prohibited. If you have received this communication in error, please erase all copies of the message and its attachments and notify us immediately. -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Is it possible to stop an image from being cached?
Tijnema wrote:
On 7/26/07, Dan [EMAIL PROTECTED] wrote:
I have a situation where there is a single image let's call it
somebody.jpg.
I want to be able to dynamicly create this image using php, basicilly
I have
PHP set to handle .jpg files also, so I then go through and create an
image
based upon some info I get from a database call and then use
header('Content-Type: image/jpeg');
passthru($file);
to send the image to the user.
My problem is once they view the image their browser helpfully
caches it
so they don't have to download it again.
Is there any tactic short of changing the name constantly of the image to
avoid browser caching of an image?
- Dan
Solution 1:
Send a header() that avoids caching (can't remember it exactly)
You can try:
header('Cache-Control: no-store, no-cache, must-revalidate,
Post-Check=0, Pre-Check=0');
brian
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Re: [PHP] Is it possible to stop an image from being cached?
Well, this is only one specific image that constantly changes, the rest of
the page is handled regularly.
From what you've said if I go with this
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
That will effect only the one specific image I use this on when generating
it right?
- Dan
Tijnema [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
On 7/27/07, Dan [EMAIL PROTECTED] wrote:
Is this header you're refering to the header of the page which contains
the
image, or the image itself?
- Dan
The image itself.
Also note, that if you use my solution 2, you still might get
problems, as the page that is calling might be cached, and in the
cached page, it refers to the image with the same unique code, and it
will use the cached image again.
Also, if you use solution 2, the image will still stay forever in the
temp folder of the browser(unless the user is cleaning it). If you use
solution 1, the browser will keep it only for this page, and will
remove it afterwards.
Tijnema
Tijnema [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
On 7/27/07, brian [EMAIL PROTECTED] wrote:
Tijnema wrote:
On 7/26/07, Dan [EMAIL PROTECTED] wrote:
I have a situation where there is a single image let's call it
somebody.jpg.
I want to be able to dynamicly create this image using php,
basicilly
I have
PHP set to handle .jpg files also, so I then go through and create
an
image
based upon some info I get from a database call and then use
header('Content-Type: image/jpeg');
passthru($file);
to send the image to the user.
My problem is once they view the image their browser helpfully
caches it
so they don't have to download it again.
Is there any tactic short of changing the name constantly of the
image
to
avoid browser caching of an image?
- Dan
Solution 1:
Send a header() that avoids caching (can't remember it exactly)
You can try:
header('Cache-Control: no-store, no-cache, must-revalidate,
Post-Check=0, Pre-Check=0');
brian
That's HTTP/1.1 only, but this is what I got from PHP site:
?php
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
?
Tijnema
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Re: [PHP] Is it possible to stop an image from being cached?
Is this header you're refering to the header of the page which contains the
image, or the image itself?
- Dan
Tijnema [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
On 7/27/07, brian [EMAIL PROTECTED] wrote:
Tijnema wrote:
On 7/26/07, Dan [EMAIL PROTECTED] wrote:
I have a situation where there is a single image let's call it
somebody.jpg.
I want to be able to dynamicly create this image using php, basicilly
I have
PHP set to handle .jpg files also, so I then go through and create an
image
based upon some info I get from a database call and then use
header('Content-Type: image/jpeg');
passthru($file);
to send the image to the user.
My problem is once they view the image their browser helpfully
caches it
so they don't have to download it again.
Is there any tactic short of changing the name constantly of the image
to
avoid browser caching of an image?
- Dan
Solution 1:
Send a header() that avoids caching (can't remember it exactly)
You can try:
header('Cache-Control: no-store, no-cache, must-revalidate,
Post-Check=0, Pre-Check=0');
brian
That's HTTP/1.1 only, but this is what I got from PHP site:
?php
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
?
Tijnema
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Re: [PHP] Is it possible to stop an image from being cached?
On 7/27/07, Chris Aitken [EMAIL PROTECTED] wrote:
header('Cache-Control: no-store, no-cache, must-revalidate,
Post-Check=0, Pre-Check=0');
brian
That's HTTP/1.1 only, but this is what I got from PHP site:
?php
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
?
But wouldn't that make every image on the page be uncached and reloaded each
time? Not very efficient if the shell of the site keeps getting loaded if
only 1 or 2 images need to be forced.
Regards
Chris Aitken
The Web Hub Designer and Programmer
Phone : 02 4648 0808
Mobile : 0411 132 075
Yes, that depends on which way it is used, I wouldn't recommend
loading images from the database that don't get changed...
And you can of course also use an
if-statement/switch-statement/in_array function in your image.php
script, like this:
$img = $_GET['img'];
if($img == test_a.jpg || $img == test_b.jpg) {
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
}
OR:
$img = $_GET['img'];
switch($img) {
case test_a.jpg:
case test_b.jpg:
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
}
OR:
$img = $_GET['img'];
$noncached_images = array(test_a.jpg,test_b.jpg);
if(in_array($img,$noncached_images)) {
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
}
Tijnema
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Re: [PHP] Is it possible to stop an image from being cached?
On 7/26/07, Dan [EMAIL PROTECTED] wrote:
I have a situation where there is a single image let's call it somebody.jpg.
I want to be able to dynamicly create this image using php, basicilly I have
PHP set to handle .jpg files also, so I then go through and create an image
based upon some info I get from a database call and then use
header('Content-Type: image/jpeg');
passthru($file);
to send the image to the user.
My problem is once they view the image their browser helpfully caches it
so they don't have to download it again.
Is there any tactic short of changing the name constantly of the image to
avoid browser caching of an image?
- Dan
Solution 1:
Send a header() that avoids caching (can't remember it exactly)
Solution 2:
Call the image like this:
img src=image.jpg?arandomstringhereeachtime
Or if you were creating it with a php script:
img src=image.php?img=image.jpgarandomstringhereeachtime
Tijnema
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Re: [PHP] Is it possible to stop an image from being cached?
Awesome, seems to work. Thanks Tijnema!
- Dan
Dan [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
Well, this is only one specific image that constantly changes, the rest of
the page is handled regularly.
From what you've said if I go with this
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
That will effect only the one specific image I use this on when generating
it right?
- Dan
Tijnema [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
On 7/27/07, Dan [EMAIL PROTECTED] wrote:
Is this header you're refering to the header of the page which contains
the
image, or the image itself?
- Dan
The image itself.
Also note, that if you use my solution 2, you still might get
problems, as the page that is calling might be cached, and in the
cached page, it refers to the image with the same unique code, and it
will use the cached image again.
Also, if you use solution 2, the image will still stay forever in the
temp folder of the browser(unless the user is cleaning it). If you use
solution 1, the browser will keep it only for this page, and will
remove it afterwards.
Tijnema
Tijnema [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
On 7/27/07, brian [EMAIL PROTECTED] wrote:
Tijnema wrote:
On 7/26/07, Dan [EMAIL PROTECTED] wrote:
I have a situation where there is a single image let's call it
somebody.jpg.
I want to be able to dynamicly create this image using php,
basicilly
I have
PHP set to handle .jpg files also, so I then go through and create
an
image
based upon some info I get from a database call and then use
header('Content-Type: image/jpeg');
passthru($file);
to send the image to the user.
My problem is once they view the image their browser helpfully
caches it
so they don't have to download it again.
Is there any tactic short of changing the name constantly of the
image
to
avoid browser caching of an image?
- Dan
Solution 1:
Send a header() that avoids caching (can't remember it exactly)
You can try:
header('Cache-Control: no-store, no-cache, must-revalidate,
Post-Check=0, Pre-Check=0');
brian
That's HTTP/1.1 only, but this is what I got from PHP site:
?php
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
?
Tijnema
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Re: [PHP] Is it possible to stop an image from being cached?
On 7/27/07, Dan [EMAIL PROTECTED] wrote:
Is this header you're refering to the header of the page which contains the
image, or the image itself?
- Dan
The image itself.
Also note, that if you use my solution 2, you still might get
problems, as the page that is calling might be cached, and in the
cached page, it refers to the image with the same unique code, and it
will use the cached image again.
Also, if you use solution 2, the image will still stay forever in the
temp folder of the browser(unless the user is cleaning it). If you use
solution 1, the browser will keep it only for this page, and will
remove it afterwards.
Tijnema
Tijnema [EMAIL PROTECTED] wrote in message
news:[EMAIL PROTECTED]
On 7/27/07, brian [EMAIL PROTECTED] wrote:
Tijnema wrote:
On 7/26/07, Dan [EMAIL PROTECTED] wrote:
I have a situation where there is a single image let's call it
somebody.jpg.
I want to be able to dynamicly create this image using php, basicilly
I have
PHP set to handle .jpg files also, so I then go through and create an
image
based upon some info I get from a database call and then use
header('Content-Type: image/jpeg');
passthru($file);
to send the image to the user.
My problem is once they view the image their browser helpfully
caches it
so they don't have to download it again.
Is there any tactic short of changing the name constantly of the image
to
avoid browser caching of an image?
- Dan
Solution 1:
Send a header() that avoids caching (can't remember it exactly)
You can try:
header('Cache-Control: no-store, no-cache, must-revalidate,
Post-Check=0, Pre-Check=0');
brian
That's HTTP/1.1 only, but this is what I got from PHP site:
?php
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
?
Tijnema
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Re: [PHP] Is it possible to stop an image from being cached?
On 7/27/07, brian [EMAIL PROTECTED] wrote:
Tijnema wrote:
On 7/26/07, Dan [EMAIL PROTECTED] wrote:
I have a situation where there is a single image let's call it
somebody.jpg.
I want to be able to dynamicly create this image using php, basicilly
I have
PHP set to handle .jpg files also, so I then go through and create an
image
based upon some info I get from a database call and then use
header('Content-Type: image/jpeg');
passthru($file);
to send the image to the user.
My problem is once they view the image their browser helpfully
caches it
so they don't have to download it again.
Is there any tactic short of changing the name constantly of the image to
avoid browser caching of an image?
- Dan
Solution 1:
Send a header() that avoids caching (can't remember it exactly)
You can try:
header('Cache-Control: no-store, no-cache, must-revalidate,
Post-Check=0, Pre-Check=0');
brian
That's HTTP/1.1 only, but this is what I got from PHP site:
?php
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
?
Tijnema
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Re: [PHP] Is it possible to stop an image from being cached?
On Thu, July 26, 2007 6:32 pm, Tijnema wrote: Also, if you use solution 2, the image will still stay forever in the Not forever. Just until something else being downloaded shoves it out due to the folder size restriction. The browser might even be smart and keep oft-used resources in the cache in favor of others rather than be strictly FIFO. So a random URL makes browsers that were dumb enough to cache something they shouldn't have cached (if you sent no cache headers) clog up their cache with the un-re-usable files that it shouldn't have saved anyway. Oooh, hurt me. :-) -- Some people have a gift link here. Know what I want? I want you to buy a CD from some indie artist. http://cdbaby.com/browse/from/lynch Yeah, I get a buck. So? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
Re: [PHP] Is it possible to stop an image from being cached?
On Thu, July 26, 2007 4:56 pm, Dan wrote: Is there any tactic short of changing the name constantly of the image to avoid browser caching of an image? You can try to use all the zillion header calls people will send you. Somewhere out there is a really stupid browser that will insist on caching it. src=somebody.jpg??php echo uniqid()? will make it very difficult for any halfway-decent browser to cache. However, that can lead to some issues when the URL of the image is embedded elsewhere, as some folks will strip off the GET arg on the assumption that it's invalid for a JPEG. Embedding the random bit so that it LOOKS like a directory, but isn't, will avoid that problem. I blogged about how to do this kind of thing (in another context) over here: http://richardlynch.blogspot.com/2006/06/php-downloads-content-disposition.html There are shorter / better explanations out there, but I don't know where without Googling, and you know how to Google, right? -- Some people have a gift link here. Know what I want? I want you to buy a CD from some indie artist. http://cdbaby.com/browse/from/lynch Yeah, I get a buck. So? -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
RE: [PHP] Is it possible to stop an image from being cached?
header('Cache-Control: no-store, no-cache, must-revalidate,
Post-Check=0, Pre-Check=0');
brian
That's HTTP/1.1 only, but this is what I got from PHP site:
?php
header(Cache-Control: no-cache, must-revalidate); // HTTP/1.1
header(Expires: Mon, 26 Jul 1997 05:00:00 GMT); // Date in the past
?
But wouldn't that make every image on the page be uncached and reloaded each
time? Not very efficient if the shell of the site keeps getting loaded if
only 1 or 2 images need to be forced.
Regards
Chris Aitken
The Web Hub Designer and Programmer
Phone : 02 4648 0808
Mobile : 0411 132 075
-
Making The Web Work The Web Hub
http://www.thewebhub.com.au/
[EMAIL PROTECTED]
-
Confidentiality Statement:
This message is intended only for the use of the Addressee and may contain
information that is PRIVILEDGED and CONFIDENTIAL. If you are not the
intended recipient, dissemination of this communication is prohibited.
If you have received this communication in error, please erase all
copies of the message and its attachments and notify us immediately.
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