Strange but important question

Jazzy_Girl

Hi, I have some php that calls text from my database. Just to see if it would work to perhaps help me later, I put a some php code into the database to be put onto my web page as well after all the other database entries.

I notice that the code is not exectuted when its from the database. Even though
the php code looks exactly the same on my page even if it hadn't been from a database. Anyone know why the browsers and servers won't recognize the php when it comes from a database? Example. This is code that calls a file randomly. But when I put it on my page through the database it won't work. Even though it looks just like this, and should be working, and normally works when put on the page the regular way. Please let me know, thank you very much.

<?php
$getfile = rand(5,10);
$includefile = "file" . $getfile . ".txt";
include ($includefile);
?>

NogDog

Well, you don't show how you're grabbing the code from the database and what you subsequently do with it, but you can't just echo/print it out. If you do that, all you're doing is outputting that text to the client (the browser). But PHP gets executed on the server, not the client.

You'll either need to (a) use eval() to execute the extracted code, (b) create a separate servlet PHP file to extract the text from the database so that you can then "include" that servlet, or (c) rethink the whole logic of storing PHP in a database.

Jazzy_Girl

Thank you, I hope you or someone doesn't mind explaining a bit more about the server client. Then I will understand a lot more about this and know which one of your options I should be checking into.

It might have something to do with the fact that the php code is already within the other php code, which is calling everything from the database. So the server isn't reading it as its own code. How can I get the server to read it as its very own code, even though it is within the other php code that does something else. Hope that makes sense. I really need to figure this out. I can't explain all the reasons why, only to say that it is imporatant. Any thoughts on this are appreciated. Thank you.

tomhath

Jazzy Girl wrote:
How can I get the server to read it as its very own code, even though it is within the other php code that does something else...

The "eval" function that NogDog pointed to is what you use to run php code that is stored in a variable. Follow the link he provided and try the examples. But mixing php code in with the text in your database will make everything more complicated.

What php code are you putting in the text? Can you use javascript instead?

Jazzy_Girl

Thank you very much. Unfortunately php manual makes my head spin and I think it does others like me that only know some scripting. Only a few of their explanations have made perfect sense to me. I wish they would show more of simple examples. I really would like to learn more about eval(). I did a google search as well but am no further than before. So I guess I need to ask more questions. I can't use javascript. I realize that since php is a server side script that it executes once when the page loads. I am worrying about all those details later. Right now I just would like the database to put the php script on the page and then I can figure out how to rexecute it with a refresh or something. For example right now the database puts this on my page
<?php
$getfile = rand(10,31);
$includefile = "file" . $getfile . ".txt";
include ($includefile);
?>
But it won't re-execute even when I do a refresh for the page. I believe it is because it is already put on the page with php. How can eval() or something else help with this? I'd really like to know, please get back to me, thanks a lot.

tomhath

When you request a page such as http://localhost/index.php, think of it this way (very simplified):

1) The web server will look for a file with that name (index.php). The server is a program such as Apache's httpd.exe. This is important: the web server must get a request for a file that it can find. Okay, there are other options in other programming languages, but I'll ignore that complication for now.

2) If the server recognizes the file's extension as a script it can run (in this case index.php) it will run the script interpreter with that file as input (the interpreter is a program like php.exe or mod_php depending on the server and operating system).

3) The script interpreter will write a stream of data that is sent back to whatever requested it (usually your browser). At this point the interpreter is done running your file (index.php) so it exits or waits for another file to run.

3) The browser will look at the beginning of the data stream for a tag called the MIME TYPE and decide what to do with it (text, html, jpg, ...).

So where you're going wrong is having the script interpreter write a stream of data that contains php back to the browser. The browser thinks what you sent it is just regular text or html, it doesn't know anything about php. The web server never tried to run the php you read from the database.

So what does "eval" have to do with anything? While the interpreter is running, it can temporarily stop running the input file and run a script from somewhere else. So instead of running php code it found in index.php, the interpreter will run your php script from the database that you have in a variable.

Get it clear in your head that having the interpreter run the script is entirely different from having it write the php back to the browser.

Try this very simple example:

<?php
$foo = "Hello, world!\n";
eval('echo $foo;');
?>

If you want it to run the include file, try it like this:

test.php

<?php
    echo "Hello ";

$f = "test_include.php";
include ($f);
?>

And the included file (make sure it has the <?php tags around it):

test_include.php

<?php
echo "World";
?>

Jazzy_Girl

Thank you very, very, much for taking the time to tell me that. I am keeping it until it sinks in very well. No wonder I'm having trouble, that is just a bit complicated. Appreciated very much. Thanks again.