Using a variable in $_POST['$variable'];

Brutal

I have a pretty long page with several input fields that have been generated automatically from a SQL-query. The fields are named after the acutal fieldnames in the table with "qty" added to the end. For example "Item1" => Item1qty, Item2qty and so on..

Now in my handler I want to loop through all theese to see if there is a value entered and if so, update the table.

my approach to extrack the POST variable was like this ...

$qry = "SELECT typeID, typeName FROM tblInventory";
the query stuff

while ( $row = mysql_fetch_array( $qry_result )
{
  $tmp = $row['typeName']."Qty";
  $newVal = $_POST['$tmp'];

  if( $newVal != 0 ) then do some insertion stuff ...
}

Now, that $newVal variable is empty ... every time, is there something I have missed about this?

Rodney_H_

this might help:

When you put the variable, $tmp, within single quotes, it is treated literally as a string comprising of: a dollar sign and the letters t-m-p.

So, if you want to use that variable as an array key, do not put it in quotes, and just use: $_POST[$tmp]

Conceptually, to do what you want in another way, you can do your selection of current values from the DB first, when you render the form, and place the current values in HIDDEN form fields.

Then, upon form submission, you can compare the original value in the HIDDEN field against the new value entered by the user. if they are different, you then run your UPDATE routine...

HTH....

Brutal

Oh, ty! All theese single, double quotes is kinda confusing in the beginning. Often I mess it up to much instead of just doing it plain and simple, which often is the right way.

Anyway, while we are at it ...

I have the following contruction as well, which I have done mainly because of the fact that I cant seem to get it right ...

$val = $_POST['value'];
$qry = "SELECT * FROM table WHERE id = $val";

NOW, if I want to skip the extra step by declaing a variable $val, and instead just put the POST right into $qry?

Rodney_H_

Brutal wrote:
NOW, if I want to skip the extra step by declaing a variable $val, and instead just put the POST right into $qry?

Yes, I would do it as such:

// I would Type cast the value, if you are expecting an integer
$qry = "SELECT * FROM table WHERE id = " . (int)$_POST['value'];

// OR, validate:
if(!ctype_digit($_POST['value'])) exit('invalid user input!');
else $qry = "SELECT * FROM table WHERE id = " . $_POST['value'];