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PHP : Delayed database request also without live page

Answer 1

+1 A:

Perhaps you want to use a javascript command to initiate the delay, because with Javascript you can send data to PHP via AJAX, and if you encapsulate this AJAX in a function and then call this from your "delay" function.

For the page leaving you could also use:

window.onbeforeunload=delayFunction;

Hope this helps.

Daniel Hanly 2010-08-31 08:48:54

I must add, this is an inadvisable action because if you have an internet outage as @Victor Nicollet suggests, then you would have no data send. Why can't you send immediately?

Daniel Hanly 2010-08-31 08:55:15

Your example is great too in some situation, and thanks for `onbeforeunload` I never know that this exists :D

CIRK 2010-08-31 09:18:28

Cheers mate, but after you added the travian example, this solution isn't good enough. At least now you can keep this knowledge for now :)

Daniel Hanly 2010-08-31 09:19:28

Answer 2

+1 A:

This is impossible. The user might leave the page because their internet connection failed or because there's a power outage, at which point there's no way to have them send the information to the database.

What you can do is store the data in the database immediately, with a "do not open before" timestamp to simulate a one-minute delay, and add the additional constraint to all requests against that table:

WHERE createDate < NOW()

Victor Nicollet 2010-08-31 08:49:55

Maybe in PHP exclusively, but there are javascript functions that allow it.Web development these days is very much a combination of different languages and methods so using <script> </script> inside a PHP page is acceptable

Daniel Hanly 2010-08-31 08:52:20

@Daniel Hanly: what is the JavaScript function that lets you send data to a server during a power outage or internet connection failure?

Victor Nicollet 2010-08-31 08:53:50

You make a good point, but you perhaps shouldn't suggest that something is impossible. Perhaps inadvisable, but not impossible.

Daniel Hanly 2010-08-31 08:56:08

Well I was thinking something very similar in my mind, however I didn't know what is it. This is a really good idea.

CIRK 2010-08-31 08:59:43

@Daniel Hanly: did you read the whole answer? While this is impossible with *only* JavaScript, @Victor Nicollet has suggested a perfectly viable solution in the second paragraph.

Piskvor 2010-08-31 09:02:11

I say it's impossible because there is no reliable way to have client-side code (such as JavaScript) run for 30 seconds after the user has left the page. All solutions posted so far have the client send the data (unreliably) when the page is left, which leaves the server with the task of waiting 30 seconds before inserting the data. At that point, sending the data straight away and handling the delay in the database is more reliable and does not require any client-side code.

Victor Nicollet 2010-08-31 09:03:00

@Victor Nicollet: I have a feeling that's exactly what happens in the first example (Travian): the request is sent, (target time is inserted into db), page refreshes, user is shown countdown *to a time that's already in the database*

Piskvor 2010-08-31 09:13:37

@Piskvor Before the OP added his travian and blogging example I had assumed that he meant almost like a "1 minute confirmation time" of a form submission, for which @Victor's answer wouldn't be the best solution. However, now the OP has added those examples, I would now offer the same solution as Victor, but it's too late to take away my down vote. I still don't agree with suggesting things are impossible, but his solution is Valid. Sorry mate!

Daniel Hanly 2010-08-31 09:16:17

Answer 3

A:

there is no guarantee for this action. I can leave page with closing browser too. Building database-driven solution is the best.

Burçin Yazıcı 2010-08-31 08:52:43

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