WebDevKungfu

extract(); - Very useful indeed…

May 3, 2005 Code, Web Dev

Pulling in $_POST or $_GET variables can be quite a pain sometimes, enter a handy built-in PHP function: extract()





Let’s pretend your making a contact form, that when a user clicks submit goes to “process_contact.php” That would mean that your query string would look something like this:

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process_contact.php?name=Some%20Visitor&
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email=visitor@domain.com&message=Hello%20World
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Typically you would have to do the following:

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$name = $_GET['name'];
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$email = $_GET['email'];
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$message= $_GET['message'];
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That’s not bad for just three items but what if it was an online survey and you wanted to gather all the $_GET data from that? Wouldn’t it be nice if PHP could automate it for you?

It can. With 1 (yes that’s right 1) line of code.

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extract($_GET, EXTR_PREFIX_SAME, "var");
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That function, which is a built-in PHP function by the way is extracting all the query string variables (in our case: name, email & message) and setting them equal to their respective values (in our case: Some Visitor, visitor@domain.com, Hello World)
So to access those variables we just do this:

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echo $name;
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echo $email;
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echo $message;
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The EXTR_PREFIX_SAME is basically saying if Joe Programmer has already made a variable called $name (or any other that would exactly match one from the query string) Then we are going to prefix it with “var”

Here is an example:

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$name = Tom;
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extract($_GET, EXTR_PREFIX_SAME, "var");
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echo "This is the name we declared--->".$name."
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";
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echo "This is the name from query string--->".$var_name."
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";
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And one last cool thing about extract(); It will work with ANY array.
Example:

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$test = array ('label1' => 1, 'label2' => 2);
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extract($test, EXTR_PREFIX_SAME, "var");
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echo "Label1 --->" .$label1."
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";
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echo "Label2 --->" .$label2."
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";
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How sweet is that? Enjoy.

For more info about extract(); be sure to check out the manual (www.php.net)